A carburetor engine differs from an injection engine not only in its design, but also in its operating features. This article talks about what needs to be taken into account when operating an engine with a carburetor, how to maintain it, how to make basic adjustments, and what problems owners of cars with carburetor engines most often encounter.

position (to drown). Most modern carburetors are equipped with a semi-automatic control system that opens the choke as the engine warms up, so the driver only needs to pull out the choke handle and start the engine, and automatic operation will ensure stable operation. Carburetor adjustments In any carburetor there are several main adjustment elements made in the form of screws: - Quality screw - provides adjustment of the quality of the fuel-air mixture, with its help the composition of the mixture changes (by changing the fuel concentration); - Quantity screw - provides adjustment of the amount of mixture entering the cylinders at Idling, with its help the number of engine revolutions at idle changes; - Toxicity screw - provides adjustment of the composition of the fuel-air mixture by changing the amount of air supplied to the atomizer through the main air jet. Carburetors can produce

Carburetor: how to create a nutrient mixture for the engine

Despite the spread of fuel injection systems, Russian roads there are still many cars with carburetor engines, and this must be taken into account. Read about what a carburetor is, why it is needed in a car, what kind of device it has and on what principles its operation is based.

indicators, and even one engine at different operating modes requires a mixture with different concentrations of fuel and air. Therefore, a modern carburetor is a complex unit with several systems necessary to ensure operation power plant in any conditions and in any modes. Types and types of carburetors There are several types of carburetors, but today only two of them are widespread: - Membrane-needle; - Float. The membrane-needle carburetor is inexpensive and simple in design, but has a number of disadvantages, and therefore has received limited distribution on cars. But, on the other hand, this carburetor can operate in almost any position, therefore it is widely used on low-power engines of devices such as lawn mowers, chainsaws and others. econostat emulsion jet; econostat emulsion channel; air jet of the main dosing system;

PAZ buses with automatic transmission: new cars for modern cities

Pavlovsk Bus Plant has been producing its buses since 1952, and all these sixty years PAZs have been faithfully serving in Russian cities and villages. In recent years, PAZ has taken a course towards modernization and creating a truly modern cars. Among the new products of the plant are PAZ city buses, equipped automatic transmission transmission These machines will be discussed in this article.

It is only possible to carry out the following work: - Replace the filter every 80,000 km; - Oil change every 120,000 km. The total resource of the box reaches 500,000 km or more. Allison also provides a company warranty for 3 years without mileage limitation, and in the event of a breakdown, you will not have to buy PAZ spare parts - Allison will simply replace the box. PAZ model range with automatic transmission The Pavlovsk plant produces two models of buses with an Allison automatic transmission: - Middle class bus PAZ-320412-05; - City low-floor middle class bus PAZ-3237. It is also possible to install the Allison 2000 series automatic transmission on other models of Pavlovsk buses, mainly on city buses. PAZ-320412-05 “Vector”. A middle class city bus with a capacity of 60 passengers (22 seats). Equipped with diesel Cummins engine ISF Euro-4 class and Allison 2100 automatic transmission. Created on the basis of earlier

Carburetors K-126, K-135. Guide - part 3

flow area of valve 6 (Fig. 8) by valve needle 5, driven by tongue 4 on
float holder.

Rice. 8. Float mechanism
carburetor:
1 - float; 2 - travel limiter
float; 3 - float axis; 4 - tongue
level adjustment; 5 - valve needle; 6 -
valve body; 7 - sealing washer;
A - distance from the plane of the connector
covers up top point float; IN -
gap between the end of the needle and the tongue

When the fuel level drops

below a given value, as in falling with
it, the float will lower the tongue, which will give
possibility of needle 5 under pressure

the fuel created by the fuel pump and its own weight drop down and pass into the chamber
more gasoline. It can be seen that fuel pressure plays a certain role in the operation
float chamber. Almost all gasoline pumps must create a gasoline pressure of 15...30
kPa. Deviations in a larger direction can even with correct adjustments float
mechanism to create fuel leakage through the needle. To control the fuel level in earlier
modifications of the K-126 had an inspection window on the wall of the float chamber housing. By cr
window, approximately along its diameter, there were two tides that marked the line of normal
fuel level. In by

In the latest modifications, the window is missing, and the normal level is marked

is. 9. Side view of the carburetor

camera

fuel

la promoted

The hole on the needle of valve 5 (Fig. 8) is wearing a small

It cannot be either brass or plastic. Reliability

you erase it.

mark 3 (Fig. 9) on the outside of the body

1 2 3 4

R
fittings: 1 - channel into the supra-membrane
limiter; 2 - main fuel plugs
jets; 3 - fuel level risk
float chamber; 4 - supply channel
from the fuel pump; 5 - traction; 6 - selection fitting
vacuum on the recirculation valve; 7 - channel
sub-diaphragm restrictor chamber

spare parts reliability

ethane washer 7, which maintains elasticity in gasoline and reduces writing force

repeatedly. In addition, due to its deformation, the vibrations of the float are smoothed out, inevitably
arising when the vehicle is moving. If the washer is destroyed, the tightness of the assembly is immediately
is irreversibly damaged.

The float itself can

tity) of both is quite high, unless you yourself are deformed

To prevent the float from knocking on the bottom of the float chamber when there is no gasoline in it (which
most likely when operating dual-fuel gas-cylinder vehicles) on the holder according to
melting there is a second tendril 2, resting on a stand in the body. It can be adjusted by bending it

needle stroke, which should be 1.2... 1.5 mm. This tendril is also on the plastic float
plastic, i.e. it cannot be bent. The needle stroke is not adjustable.

A basic carburetor with only a diffuser, a spray nozzle, and a float chamber

and the fuel jet are able to maintain the mixture composition approximately constant throughout
air flow areas (except for the smallest ones). But to get as close as possible to the ideal
dosing characteristics, the mixture should be leaner as the load increases (see Fig. 2, section ab).
This problem is solved by introducing a mixture compensation system with pneumatic braking
fuel. It includes, installed between the fuel nozzle and the atomizer
emulsion well with an emulsion tube 13 and an air jet 12 placed in it
(see Fig. 6).

The emulsion tube is a brass tube with a closed bottom end,

having four holes at a certain height. She is lowered into the emulsion well and
it is pressed from above by an air jet screwed into the thread. With increasing load
(vacuum in the emulsion well), the fuel level inside the emulsion tube drops and
at a certain value it appears below the holes. The sprayer channel begins
air flows through the air jet and holes in the emulsion tube. This
air mixes with fuel before leaving the atomizer, forming an emulsion (hence
name), facilitating further spraying in the diffuser. But the main thing is the supply of additional
air reduces the level of vacuum transmitted to the fuel nozzle, thereby preventing
the most excessive enrichment of the mixture and giving the characteristic the necessary “slope”. Change
The cross section of the air jet will have virtually no effect at low engine loads. At
under heavy loads (high air flow rates), increasing the air jet will ensure
greater leanness of the mixture, and decrease - enrichment.

4. Idle system

At low air flow rates, which are available in idle modes, the vacuum is

There are very few diffusers. This leads to instability of fuel dosing and high
depending on its consumption on external factors, for example, fuel level, Under throttle
dampers in the intake pipe, on the contrary, it is in this mode that the vacuum is high. Therefore on
at idle speed and at small throttle opening angles, the fuel supply to the atomizer is replaced
supply under the throttle valves. For this purpose, the carburetor is equipped with a special system
idle speed (IAC).

The K-126 carburetors use a CXX scheme with throttle atomization. Air in

the engine at idle speed passes through a narrow ring-shaped gap between the walls
mixing chambers and the edges of the throttle valves. Throttle closure degree and cross section
the gaps formed are regulated by stop screw 1 (Fig. 10). Screw 1 is called screw
"quantities". By turning it in or out, we regulate the amount of air,
entering the engine, and thereby changing the engine idle speed.
The throttle valves in both chambers of the carburetor are installed on the same axis and the thrust screw
"quantity" regulates the position of both throttles. However, inevitable installation errors
throttle plates on the axle lead to the fact that the flow area around the throttles can
be different. At large opening angles, these differences against the background of large flow sections are not
noticeable. At idle, on the contrary, the slightest differences in the throttle settings become
principled. The inequality of the flow sections of the carburetor chambers causes different
air flow through them. Therefore, in carburetors with parallel opening of the throttles it is impossible
install one screw for adjusting the mixture quality. Personal adjustment required

cameras with two “quality” screws.

Rice. 10. Adjustment screws
carburetor:
1 - thrust screw of throttle valves
(quantity screw); 2 - composition screws
mixtures (quality screws);
3 - limit caps

In the family under consideration there is one carburetor K-135X, which has a system

idle speed was common to both chambers. There was only one “quality” adjusting screw and
was installed in the center of the mixing chamber housing. From it fuel was supplied to a wide
a channel from which it diverged into both chambers. This was done to organize the EPH system,
forced idle economizer. The solenoid valve blocked the common
idle channel and controlled electronic unit based on signals from the distribution sensor
ignition (speed signal) and from the limit switch installed at the propeller
"quantities". The modified screw with platform is visible in Fig. 14. Otherwise, the carburetor is not
different from K-135.

K-135X is an exception and, as a rule, there are two independent carburetors

idle systems in each carburetor chamber. One of them is shown schematically in
rice. 11. Fuel is taken from them from the emulsion well 3 of the main metering
system after the main fuel jet 2. From here, fuel is supplied to the fuel
idle jet 9, screwed vertically into the float chamber body through the cover
so that it can be unscrewed without disassembling the carburetor. Calibrated part of the jets
made on the toe, below the sealing belt, which rests against the body when screwed
Vania. If the belt does not touch tightly, the resulting gap will appear as
parallel jet with a corresponding increase in cross-section. On older carburetors
The idle fuel jet had an elongated nose that went down to the bottom of its well.
After leaving the fuel nozzle, the fuel meets the air supplied through
idle air jet 7, screwed under plug 8. The air jet is required
to reduce the vacuum on the idle fuel jet, forming the required
idle characteristics and eliminating spontaneous fuel leakage from
float chamber when the engine is stopped.

The mixture of fuel and air forms an emulsion, which flows down through channel 6 to

throttle body. Next, the flow is divided: part goes to via hole 5
just above the throttle edge, and the second part - to the “quality” adjusting screw 4. After
adjustment with a screw, the emulsion is discharged directly into the mixing chamber after
throttle valve.

On the carburetor body, “quality” screws 2 (Fig. 10) are located symmetrically in the body

chokes in special niches. To
the owner did not violate the adjustments, screws
can be filled. To do this they can
put on plastic caps 3,
rotation-limiting adjustment
screws

Rice. 11. Diagram of the idle system and
transition system: 1 - float chamber with
float mechanism; 2 - main
fuel jet; 3 - emulsion well
with emulsion tube; 4 - “quality” screw;
5 - via; 6 - supply channel
fuel to the idle system holes
progress; 7 - idle air jet; 8
- air jet plug; 9 - fuel
idle jet; 10 - input
1 air pipe

5. Transition systems

If the throttle of the primary chamber is smoothly opened, then the amount of air passing

through the main diffuser will increase, but the vacuum in it will still
will not be enough to cause fuel to flow out of the nozzle. Amount of fuel supplied
through the idle system will remain unchanged, since it is determined by the vacuum behind
throttle. As a result, the mixture during the transition from idle to the main metering operation
the system will begin to become lean until the engine stops. To eliminate the "failure"
transition systems operating at small throttle opening angles have been organized. The basis of them
constitute vias located above the upper edge of each throttle at
their position on the stop in the “quantity” screw. They act as additional air
variable-section jets that control the vacuum of the idle fuel jets.
At minimum idle speed, the transition hole is located above the throttle in the area
where there is no vacuum. Gasoline does not leak through it. When moving
throttle up, first the holes are blocked due to the thickness of the valve, and then they fall into
zone of high throttle vacuum. High vacuum is transmitted to the fuel
jet and increases fuel consumption through it. The outflow of gasoline begins not only through
exit holes after the "quality" screws, but also from the via holes in each chamber.

The cross-section and location of the via holes are selected so that when opening smoothly

throttle, the composition of the mixture should remain approximately constant. However, to solve this
The task of one via, which is available on the K-126, is not enough. Its presence is only
helps smooth out the “failure” without eliminating it completely. This is especially noticeable on the K-135, where
The idle system is made leaner. In addition, the operation of transition systems in
Each of the chambers is influenced by the identity of the installation of the throttle plates on the axle. If
one of the chokes is higher than the second, then it begins to block the via hole earlier
In another chamber, and therefore in a group of cylinders, the mixture may remain lean. Smooth out the low
The quality of the transition systems is helped again by the fact that for a truck the operating time is low
little load. Drivers “step over” this mode by immediately opening the throttle to a large angle.
To a large extent, the quality of the transition to load depends on the operation of the accelerator pump.

6. Economizer

The economizer is a device for supplying additional fuel

(enrichment) modes full loads. Enrichment is necessary only when complete
throttle openings, when the reserves for increasing the amount of mixture have been exhausted (see Fig. 2, section
bс). If enrichment k is carried out, then the characteristic will “stop” at point b and the increase
power ANe will not be achieved. We will get approximately 90% of the possible power.
In the K-126 carburetor, one economizer serves both carburetor chambers. In Fig. 12
Only one camera and its associated channels are shown.

Economizer valve 12 is screwed into the bottom of a special niche in the float chamber. Over it

There is always gasoline. In the normal position the valve is closed, and to open it
must press the special rod 13. The rod is fixed on a common bar 1 together with the piston
accelerator pump 2. Using a spring on the guide rod, the bar is held in
top position. The bar is moved by a drive lever 3 with a roller,
which is turned by rod 4 from the throttle drive lever 10. The drive adjustments should
ensure that the economizer valve is activated when the throttles are opened by approximately 80%.

From the economizer valve, fuel is supplied to the block through channel 9 in the carburetor body

sprayers. The K-126 nozzle block combines two economizer nozzles 6 and
accelerator pump 5 (for each carburetor chamber). Sprayers are above the level
fuel in the float chamber and for it to flow through them, gasoline must rise by some
height. This is only possible in modes when there is a vacuum at the nozzle ends. IN
As a result, the economizer supplies gasoline only if it is simultaneously fully open
throttles and increased rotation speed, i.e. performs partly the functions of an econostat. How

The GAZ 53 carburetor has a two-chamber system, any of them works on 4 cylinders. The throttle valve is equipped with a drive for both chambers, so fuel is dosed synchronously to all cylinders. For optimal flow fuel at different engine modes, the carburetor provides several systems for regulating the composition of the fuel consistency (FC).

This is what the carburetor installed on a GAZ 53 looks like

The carburetor was initially brand K126B, its next modification was K135 (K135M). In principle, the models are practically no different, only the device’s control scheme has changed, and on the latest releases, a comfortable viewing window was removed from the float chamber. Now it has become impossible to see the level of gasoline.

Device

K-135 is emulsified, with 2 chambers and a falling flow.

The two chambers are independent of each other; through them, a flammable mixture is supplied to the cylinders through the inlet pipe. One chamber serves cylinders 1 to 4, and the other serves all others.

The air damper is located inside the float chamber and is equipped with 2 automatic valves. The main systems used in the carburetor operate on the principle of air braking of gasoline, not counting the economizer.

Have 2 cameras carburetor The only common features are a cool engine starting system, an accelerator pump, partly an economizer, which has one valve for two chambers, and also a drive mechanism. They are separately equipped with jets located in the nozzle block and related to the economizer.

Read also

Any system idle move It contains fuel and air jets, and two holes in the mixing chamber. A screw with a rubber ring is installed on the bottom hole. The screw is designed to regulate the composition of the flammable mixture. Repairing the Gas 53 carburetor involves first adjusting the Gas 53 carburetor. And the rubber seal prevents air from leaking through the screw hole.

System idle move cannot provide suitable fuel consumption in all engine operating modes, therefore, in addition to it, a main one is installed on the carburetor dosing system

home dosing system

The basis of the carburetor is the main dosing system(abbreviated as GDS). It ensures a constant composition of the vehicle and does not allow it to become lean or rich at medium speeds of a gasoline engine (ICE). Each chamber in the system is equipped with one fuel and one air jet.

System idle move

System idle move designed to ensure smooth operation of the engine at idle speed ICE. Throttle valve carburetor should always be slightly open, and the gasoline mixture at idle speed (idle) enters the intake tract, bypassing the gas pump. Throttle axis position is set quantity screw, and the property screws (one for each chamber) allow you to enrich or lean the mixture at idle. The fuel consumption of the vehicle largely depends on the adjustment.

Float chamber

The float chamber is located in the main body and maintains the level of gasoline in the carburetor necessary for normal operation of the engine power system. The main elements in it are a float and a locking mechanism, consisting of a needle with a membrane and a valve seat.

Economizer

The video may be especially interesting to all owners of Cars with carburetor K-135. GAZ-66. Adjusting IDLE gas 53 restoration Repair, tuning and installation. And for others, how.

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The economizer system enriches the vehicle at high engine speeds with increasing load. The economizer has a valve that, at the highest opening of the throttle valves, releases a portion of additional fuel through the channels, bypassing the GDS.

Acceleration pump

In the K126 (K135) carburetor, the accelerator is a piston with a cuff that operates in a cylindrical channel. At the moment of sharp pressing of the gas pedal, the throttle valve drive, mechanically connected to the accelerator system, forces the piston to move rapidly along the channel.

Device diagram carburetor K126 with the titles of all parts

Speed limiter

Read also

The system prevents the crankshaft from exceeding a certain number of revolutions due to incomplete opening of the throttle valve. The work is based on pneumatics; due to the vacuum, the diaphragm in the pneumatic valve of the device moves, turning the throttle valve axis mechanically connected to the limiter assembly.

Starting system

The starting system ensures smooth operation of a cool engine. The system consists of pneumatic valves located in the air damper and a system of levers that connect the throttle and air damper. When the choke cable is pulled, the air damper is locked, the rods pull the throttle along with them and open it slightly.

When starting a cool engine, the 53 gas valves in the air damper open under the influence of vacuum and add air to the carburetor, preventing the engine from stalling at a very rich consistency.

Malfunctions carburetor

There may be many different defects in the carburetor of a GAZ 53 car, but they are all associated with increased fuel consumption, regardless of whether the mixture enters the cylinders rich or lean. In addition to excessive fuel consumption, the following signs of defects are characteristic:

Dark smoke is coming from exhaust pipe. It is especially noticeable with a sharp increase in engine speed. In this case, shots may be fired into the silencer;

Carburetor repair for GAZ 53 truck

Repair carburetor First of all, it involves flushing and purging all systems. To do this, the carburetor is removed and disassembled to clean all the jets.

Adjustment

idle move;

Only one adjustment produced without disassembling itself carburetor- This is the engine idling. This procedure is performed most often; any driver can perform it. It is better to entrust the remaining adjustments to specialists, but there are often craftsmen who make any adjustments with their own hands. For proper adjustment, the XX engine must be technically sound, all cylinders must work without interruption.

Idle speed adjustment:

quantity screw
quantity screw

Buying a K135 carburetor is not a problem - it is sold in many auto stores. True, the price for such a device is rather high - about 7000-8000 rubles. K126B can no longer be found in stores; it has long been discontinued. But they are often sold through advertisements, and you can buy a practically new carburetor (2500-3000 rubles). A repair kit for the K135 model costs on average 250-300 rubles.

Adjusting the GAZ-53 carburetor

The GAZ 53 carburetor has a two-chamber system, each of which operates on 4 cylinders. The throttle valve is equipped with a drive for both chambers at once, so fuel is dosed synchronously to all cylinders. For rational fuel consumption at different engine modes, the carburetor is equipped with several systems for regulating the composition fuel mixture(TS).

This is what the carburetor installed on a GAZ 53 looks like

The carburetor was originally brand K126B, and its subsequent modification was K135 (K135M). Fundamentally, the models are almost no different, only the control scheme of the device has changed, and on the latest releases a convenient viewing window was removed from the float chamber. Now it has become impossible to see the gasoline level.

Device

K-135 is emulsified, with two chambers and a falling flow.

The two chambers are independent of each other; through them, the combustible mixture is supplied to the cylinders through the intake pipe. One chamber serves cylinders 1 to 4, and the other serves all the others.

The air damper is located inside the float chamber and is equipped with two automatic valves. The main systems used in the carburetor operate on the principle of air braking of gasoline, except for the economizer.

In addition, each chamber has its own idle system, main dosing system and sprayers. The two carburetor chambers have in common only a cold engine starting system, an accelerator pump, partly an economizer, which has one valve for two chambers, and a drive mechanism. The jets located in the nozzle block and related to the economizer are installed separately on them.

Each idle system includes fuel and air jets, and two holes in the mixing chamber. A screw with a rubber ring is installed on the bottom hole. The screw is designed to regulate the composition of the combustible mixture. And the rubber seal prevents air from penetrating through the screw hole.

The air jet, in turn, plays the role of emulsifying gasoline.

The idle system cannot provide the required fuel consumption in all engine operating modes, so in addition to it, a main system is installed on the carburetor dosing system, which consists of diffusers: large and small, fuel and air jets and an emulsified tube.

Main dosing system

The basis of the carburetor is the main dosing system(abbreviated as GDS). It ensures a constant composition of the vehicle and does not allow it to become lean or rich at medium engine speeds internal combustion(ICE). Each chamber in the system is equipped with one fuel and one air jet.

System idle move

System idle move designed to ensure stable operation of the engine at idle speed of the internal combustion engine. The carburetor throttle valve should always be slightly open, and the gasoline mixture at idle speed (idle) enters the intake tract, bypassing the GDS. The position of the throttle axis is set by the quantity screw, and the quality screws (one for each chamber) allow you to enrich or lean the mixture at idle. The fuel consumption of the vehicle largely depends on the adjustment.

Float chamber

The float chamber is located in the main body and maintains the level of gasoline in the carburetor necessary for the normal operation of the engine power system. The main elements in it are a float and a locking mechanism, consisting of a needle with a membrane and a valve seat.

Economizer

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Nail Poroshin will tell you and show once again that the process of finding a spot on the XX is applicable to any carburetor.

The economizer system enriches the vehicle at high engine speeds with increasing load. The economizer has a valve that, when the throttle valves are opened to maximum, releases a portion of additional fuel through the channels, bypassing the GDS.

Acceleration pump

In the K126 (K135) carburetor, the accelerator is a piston with a cuff that operates in a cylindrical channel. At the moment of sharp pressing of the accelerator (gas) pedal, the throttle valve drive, mechanically connected to the accelerator system, causes the piston to quickly move along the channel.

Diagram of the K126 carburetor with the names of all elements

Speed limiter

The system prevents the crankshaft from exceeding a certain number of revolutions due to incomplete opening of the throttle valve. The operation is based on pneumatics; due to the vacuum, the diaphragm in the pneumatic valve of the device moves, turning the throttle valve axis mechanically connected to the limiter assembly.

Starting system

The starting system ensures stable operation of a cold engine. The system consists of pneumatic valves located in the air damper and a system of levers that connect the throttle and air damper. When the choke cable is pulled, the air damper closes, the rods pull the throttle along with them and open it slightly.

When starting a cold engine, the 53 gas valves in the air damper open under the influence of vacuum and add air to the carburetor, preventing the engine from stalling with a mixture that is too rich.

Carburetor malfunctions

There can be many different malfunctions in the carburetor of a GAZ 53 car, but all of them are associated with increased fuel consumption, regardless of whether the mixture enters the cylinders rich or lean. In addition to increased fuel consumption, the following symptoms of malfunctions are characteristic:

There is black smoke coming from the exhaust pipe. It is especially noticeable with a sharp increase in engine speed. In this case, shots may be fired into the silencer;
The engine is unstable at idle and may also stall at idle;
The engine does not develop speed, chokes, there are pops in the intake manifold;
At sharp acceleration V internal combustion engine operation failure occurs;
Sluggish acceleration of the car, but at high speeds the car drives normally;
Lack of power, engine does not develop speed;
Jerks when moving, especially noticeable when accelerating.

Carburetor repair for GAZ 53 truck

Repairing a carburetor first of all involves flushing and purging all systems. To do this, the carburetor is removed and disassembled to clean all the jets.

Adjustment

The K126B carburetor (also the K135 carburetor) has several adjustments:

idle move;
gasoline level in the float chamber;
piston stroke of the accelerator pump;
moment when the economizer system is turned on.

Only one adjustment is made without disassembling the carburetor itself - this is idling the engine. This procedure is performed most often; any driver can perform it. It is better to entrust the remaining adjustments to specialists, but there are often craftsmen who make any adjustments with their own hands. For proper adjustment, the XX engine must be technically sound, all cylinders must work without interruption.

Idle speed adjustment:

with the engine turned off, tighten the quality screws of both chambers until the end, then unscrew each approximately 3 turns;
start the engine and warm it up to operating condition;
quantity screw set the number of revolutions XX to approximately 600. There is no tachometer in the GAZ 53 car, so the revolutions are set by ear - they should not be too low or high;
we tighten one of the screws for quality and torque until interruptions in the operation of the internal combustion engine appear, then we move the screw back approximately one-eighth of a turn (until stable operation of the engine);
We do the same with the second camera;
quantity screw set the required speed;
If necessary, use the quality screw to increase the speed if the engine stalls when you release the gas pedal.

Buy carburetor K135 is no problem - it is sold in many car dealerships. True, the price for such a device is rather high - about 7000-8000 rubles. K126B can no longer be found in stores; it has long been discontinued. But they are often sold through advertisements, and you can buy a practically new carburetor (2500-3000 rubles). A repair kit for the K135 model costs on average 250-300 rubles.

The main functions of a carburetor in a car are the preparation and dosage of a combustible mixture. On ZMZ-53 engines and on GAZ cars a carburetor of 135 is installed. The process involves uniform distribution of the combustible mixture among the cylinders power unit car.

Design and purpose of the carburetor for 135

The Gas-53 carburetor consists of several parts. Fuel consumption is controlled by independent fuel mixture control systems. Characteristics of the gas 53 carburetor has a two-chamber drive for synchronous distribution of the combustible mixture. The modification and design of the carburetor for 135 is equipped with a balanced type float chamber, this makes it possible to simultaneously open the dampers.

Diagram of the K-135 carburetor and speed limiter sensor: 1 - accelerator pump: 2 - float chamber cover; 3 - air jet of the main system; 4 - small diffuser; 5 - idle fuel jet; 6 - air damper; 7 - accelerator pump nozzle; 8 - calibrated economizer sprayer; 9 - discharge valve; 10 - idle air jet; 11 - fuel supply valve; 12-mesh filter; 13 - float; 14 - sensor valve; 15 - spring; 16 - sensor rotor; 17 - adjustment wing; 18 - viewing window; 19 - plug; 20 - diaphragm; 21 - limiter spring; 22 - throttle valve axis; 23 - limiter vacuum jet; 24 - gasket; 25 - restrictor air jet; 26 - cuff; 27 - main jet; 28 - emulsion tube; 29 - throttle valve; 30 - idle speed adjustment screw; 31 - mixing chamber housing; 32 - bearings; 33 - throttle valve drive lever; 34 - check valve accelerator pump; 35 - float chamber body; 36 - economizer valve.

Thanks to the improved intake, it was possible to achieve a more homogeneous working mixture. A new cylinder head, paired with a manifold, with high-quality tuning, leads to a reduction in toxicity. The carburetor for 135 is equipped with helical channel walls, with an increased compression ratio, allowing you to save up to 7% of fuel.

Main dosing system

The uniform, constant composition of the working fuel mixture is ensured by the main dosing system. The characteristics imply the installation of fuel and air jets on each chamber; the gas 53 carburetor contains an air atomizer as part of the dosing system. The constant composition of the mixture ensures stable operation at medium speeds of the car.

Parameters of the metering elements of the K-135 carburetor

Idle system

Stable and uniform idle speed on a gas carburetor is achieved by the position of the throttle valve. The fuel mixture enters the working part when bypassing the gas pump; the flap for unhindered access to the cylinders must be slightly open in the correct position.

Diagram of the K 135 idle system: 1 - float chamber with a float mechanism; 2 - main fuel jet; 3 - emulsion well with emulsion tube; 4 - “quality” screw; 5 - via; 6 - fuel supply valve to the openings of the idle system; 7 - idle air jet; 8 air jet plug; 9 - idle fuel jet; 10 - inlet air pipe.

The design of the carburetor for 135 provides for adjustment of the XX system. The setting directly affects fuel consumption; the quality and quantity screws adjust the mixture supply parameters.

Float chamber

The elements of the float chamber are:

A locking mechanism, the needle with a membrane of which is installed in the valve seat;
A float that regulates the amount of fuel mixture in the chambers.

Scheme for checking the fuel level in the carburetor float chamber for 135: 1 - fitting; 2 - rubber tube; 3 - glass tube.

The main purpose of the carburetor float chamber for 135 is to maintain the fuel level for stable operation of the car. The chamber is installed in the main body of the carburetor.

Economizer

For implementation full power The economizer is responsible for the engine. The device includes a valve that supplies fuel through channels, bypassing the GDS.

Carburetor economizer for 135

The gas 53 carburetor is designed in accordance with toxicity standards; at stable loads, access to the combustion chamber is blocked from excess fuel.

Acceleration pump

Scheme of the carburetor accelerator pump: 1 - rod; 2 - bar; 3 - well; 4 - spring; 5 - piston; 6 - check valve; 7 - traction; 8 - lever; 9 - throttle valve; 10 - discharge valve; 11 - sprayer.

When you press the accelerator all the way while driving, the accelerator pump built into the carburetor of the 135 model takes over. Fuel is supplied to the 135 by a piston in a cylindrical channel, which begins to enrich the mixture. The device is made with a mixture sprayer, due to this, the car picks up speed smoothly, without jerking.

Speed limiter

The system operates on pneumatics, the movement of the diaphragm occurs due to vacuum, turning the axis of the throttle valves. Mechanically connected to the limiter, the gas 53 carburetor system does not allow the throttle valves to open completely. The engine speed is controlled by the throttle.

Starting system

A cooled engine is started by the starting system. The process goes like this:

The choke drive lever, attached to the car interior, is pulled out to the required distance;
The lever system slightly opens the throttle of the air damper drive, thereby shutting off the air.

The launch is carried out by enriching the mixture and controlling the fuel supply. The characteristics of the K135 device are designed in such a way that the car engine does not stall. The air damper has a valve, under the influence of vacuum, which opens air to prevent an overly rich mixture.

Carburetor malfunctions

Failure to comply with periodicity conditions Maintenance the vehicle may cause damage. Malfunctions in the fuel supply of the gas 53 carburetor device stop normal operation for various reasons and conditions. When identifying faulty components, it is necessary to determine which unit is malfunctioning during operation. There are times when breakdowns are caused by incorrect operation of the ignition system. Before repairing, it is necessary to check the ignition system for the presence of a spark. The carburetor to 135 should be opened only in cases where the fuel supply system has been checked. Fuel supply may be difficult due to clogged fuel lines or hoses.

The main malfunctions in the operation of the gas 53 carburetor may be enrichment or over-depletion of the mixture. Both factors may be the result of incorrect adjustment to the 135, lack of tightness in the system, or clogging of the fuel supply system.

High fuel consumption, unstable idling;
Dips during acceleration or increased loads, a consequence of jamming of the accelerator pump drive piston;
Clogged jets. Occurs in an aggressive operating environment, faulty filters;
Depressurization of the body of the float chamber K135 leads to a lean mixture when the internal combustion engine operates unstably in certain modes;
Fuel overflow into the combustion chamber due to malfunctions of the float system needle leads to difficulty starting the car.

Washing and purging of systems with air flow and units is carried out when one of the causes of unstable operation is identified, as well as as a preventative measure. Typically, it is recommended to entrust gas 53 carburetor repair to specialists; they are equipped necessary tool, skills for quality work. You can adjust the idle speed groove with your own hands by removing the air filter.

Adjustment and repair

Without completely disassembling the device, it is possible to adjust only the idle level with your own hands. Fuel consumption depends directly on the crankshaft speed. The principle of operation involves adjusting the gas carburetor with 53 quality and quantity screws.

There are several adjustments:

The amount of gasoline in the float chamber;
Setting up the economizer operation;
Accelerator pump piston stroke;
Number of revolutions, idle jet.

Correct idle speed control is carried out on a working engine. Usually the procedure is performed after prophylaxis to exclude other possible reasons unstable work.

The process and scheme for adjusting the idle speed on the 53 carburetor is the following operating principle:

The adjusting screws of a cold engine are tightened until they stop, then unscrew 3 full turns. It is possible to adjust the carb with a slotted screwdriver;
Warm up the engine to operating temperature;
The number of revolutions to 135 is adjusted by ear with a screw, since the car is not equipped with a tachometer. The revolutions should be kept between high and low, weaving and jerking are unacceptable;
The K135 quality screw is tightened until the level of engine interruptions begins; it is necessary to adjust it gradually, adjust the groove with your own hands, until normal, stable operation is achieved.
The quantity is adjusted on both chambers, parallel to each other;
In cases where the car stalls when releasing the gas, it is possible to increase the operating speed.

Repair of the gas 53 carburetor is carried out in case of significant damage to the components or detected contamination. Flushing is carried out on demand; too frequent a procedure can forget the fuel supply channels and damage the devices. The most common method is to clean the float chamber. Deposits are removed only with the top layer, since stuck-on dirt can get into the inlet part of the channels and disrupt the operation of all systems. The causes of soot and deposits are poor quality or old fuel filters. Carburetor gas 53 when flushing, you should immediately replace all fuel and air filters.

During the disassembly process, it is necessary to check the condition of all elements of the system. We will repair jets, dampers and the accelerator pump, which have thin channels that, when clogged, affect engine operation.

Maintenance and possible adjustment of the gas 3307 carburetor installed on a gazelle car does not require complete removal from the engine. The plant has provided that dismantling the air filter makes it possible to routinely check the condition and adjust the idle speed. When completely cleaning and replacing components, the assembly is removed from the engine. Correct technical operation and filter replacement make it necessary to complete renovation minimal. It is enough to carry out preventive maintenance as contamination occurs in the form of flushing the K-135 carburetor.

Flushing is carried out using a flammable liquid. There are special means, the principle of which allows liquid to be delivered under air pressure to hard to reach places, grooves. External washing carried out with a brush until deposits and dirt are completely removed. Care should be taken when washing internal parts, as there is a possibility of breaking seals or clogging the channels with dirt.

The main functions of a carburetor in a car are the preparation and dosage of a combustible mixture. On ZMZ-53 engines and on GAZ cars, a carburetor of 135 is installed. The process involves uniform distribution of the combustible mixture among the cylinders of the car’s power unit.

Diagram of the K-135 carburetor and speed limiter sensor: 1 - accelerator pump: 2 - float chamber cover; 3 - air jet of the main system; 4 - small diffuser; 5 - idle fuel jet; 6 - air damper; 7 - accelerator pump nozzle; 8 - calibrated economizer sprayer; 9 - discharge valve; 10 - idle air jet; 11 - fuel supply valve; 12-mesh filter; 13 - float; 14 - sensor valve; 15 - spring; 16 - sensor rotor; 17 - adjustment wing; 18 - viewing window; 19 - plug; 20 - diaphragm; 21 - limiter spring; 22 - throttle valve axis; 23 - limiter vacuum jet; 24 - gasket; 25 - restrictor air jet; 26 - cuff; 27 - main jet; 28 - emulsion tube; 29 - throttle valve; 30 - idle speed adjustment screw; 31 - mixing chamber housing; 32 - bearings; 33 - throttle valve drive lever; 34 - accelerator pump check valve; 35 - float chamber body; 36 - economizer valve.

Main dosing system

Parameters of the metering elements of the K-135 carburetor

Options	Carburetor modifications
Diameter of large diffuser, mm	27
Diameter of mixing chambers, mm	34
Main fuel jets, cm³/min	310
Main air jets, mm, cm³/min	125
Idle fuel jets, mm, cm³/min	90
	90
Idle air jets, mm, cm³/min	600
	600
Sprayer, mm	00,75
Acceleration pump nozzle, mm	00,6
Membrane chamber jets: air cm³/min, vacuum cm³/min	60 250

Idle system

Diagram of the K 135 idle system: 1 - float chamber with a float mechanism; 2 - main fuel jet; 3 - emulsion well with emulsion tube; 4 — “quality” screw; 5—via hole; 6 — fuel supply valve to the idle system openings; 7 — idle air jet; 8 air jet plug; 9 — idle fuel jet; 10 — inlet air pipe.

The design of the carburetor for 135 provides for adjustment of the XX system. The setting directly affects fuel consumption; the quality and quantity screws adjust the mixture supply parameters.

Float chamber

The elements of the float chamber are:

A locking mechanism, the needle with a membrane of which is installed in the valve seat;
A float that regulates the amount of fuel mixture in the chambers.

Scheme for checking the fuel level in the carburetor float chamber for 135: 1 - fitting; 2 — rubber tube; 3 - glass tube.

The main purpose of the carburetor float chamber for 135 is to maintain the fuel level for stable operation of the car. The chamber is installed in the main body of the carburetor.

Economizer

The economizer is responsible for realizing the full engine power. The device includes a valve that supplies fuel through channels, bypassing the GDS.

The gas 53 carburetor is designed in accordance with toxicity standards; at stable loads, access to the combustion chamber is blocked from excess fuel.

Acceleration pump

Scheme of the carburetor accelerator pump: 1 - rod; 2 — bar; 3 - well; 4 - spring; 5 - piston; 6 - check valve; 7 - traction; 8 — lever; 9 — throttle valve; 10 - discharge valve; 11 - sprayer.

Speed limiter

Starting system

A cooled engine is started by the starting system. The process goes like this:

The choke drive lever, attached to the car interior, is pulled out to the required distance;
The lever system slightly opens the throttle of the air damper drive, thereby shutting off the air.

Carburetor malfunctions

Failure to comply with the periodicity of vehicle maintenance can lead to breakdowns. Malfunctions in the fuel supply of the gas 53 carburetor device stop normal operation for various reasons and conditions. When identifying faulty components, it is necessary to determine which unit is malfunctioning during operation. There are times when breakdowns are caused by incorrect operation of the ignition system. Before repairing, it is necessary to check the ignition system for the presence of a spark. The carburetor to 135 should be opened only in cases where the fuel supply system has been checked. Fuel supply may be difficult due to clogged fuel lines or hoses.

Basic moments:

High fuel consumption, unstable idling;
Dips during acceleration or increased loads, a consequence of jamming of the accelerator pump drive piston;
Clogged jets. Occurs in an aggressive operating environment, faulty filters;
Depressurization of the body of the float chamber K135 leads to a lean mixture when the internal combustion engine operates unstably in certain modes;
Fuel overflow into the combustion chamber due to malfunctions of the float system needle leads to difficulty starting the car.

Washing and purging of systems with air flow and units is carried out when one of the causes of unstable operation is identified, as well as as a preventative measure. Typically, it is recommended to entrust gas 53 carburetor repair to specialists; they are equipped with the necessary tools and skills for high-quality work. You can adjust the idle speed groove with your own hands by removing the air filter.

Correct idle speed control is carried out on a working engine. Usually the procedure is performed after prophylaxis in order to exclude other possible causes of unstable operation.

Type of carburetor without cover: 1 economizer rod; 2 drive bracket for echonomizer and accelerator; 3 — accelerator piston; 4 - main air jets; 5 — accelerator pump fuel supply screw; 6 — “quality” screws; 7 — “quantity” screw

The process and scheme for adjusting the idle speed on the 53 carburetor is the following operating principle:

The adjusting screws of a cold engine are tightened until they stop, then unscrew 3 full turns. It is possible to adjust the carb with a slotted screwdriver;
Warm up the engine to operating temperature;
The number of revolutions to 135 is adjusted by ear with a screw, since the car is not equipped with a tachometer. The revolutions should be kept between high and low, weaving and jerking are unacceptable;
The K135 quality screw is tightened until the level of engine interruptions begins; it is necessary to adjust it gradually, adjust the groove with your own hands, until normal, stable operation is achieved.
The quantity is adjusted on both chambers, parallel to each other;
In cases where the car stalls when releasing the gas, it is possible to increase the operating speed.

Maintenance and possible adjustment of the gas 3307 carburetor installed on a gazelle car does not require complete removal from the engine. The plant has provided that dismantling the air filter makes it possible to routinely check the condition and adjust the idle speed. When completely cleaning and replacing components, the assembly is removed from the engine. Proper technical operation and filter replacement make the need for a complete overhaul minimal. It is enough to carry out preventive maintenance as contamination occurs in the form of flushing the K-135 carburetor.

Flushing is carried out using a flammable liquid. There are special means, the principle of which allows liquid to be delivered under air pressure to hard-to-reach places and grooves. External washing is carried out with a brush until deposits and dirt are completely removed. Care should be taken when washing internal parts, as there is a possibility of breaking seals or clogging the channels with dirt.

A.N. Tikhomirov

In this article you will find:

CARBURETTORS K-126, K-135CARS GAZ PAZ

Hello friends, 2 years ago, back in 2012, I came across this wonderful book, even then I wanted to publish it, but as usual, I either had no time, or family, and now, today I came across it again and could not remain indifferent, After searching the net a little, I realized that there are a lot of sites offering to download it, but I decided to do it for you and publish it for self-development, read for health and gain knowledge.

Operating principle, device, adjustment, repair

Publishing house "WHEEL" MOSCOW 2002

This brochure is intended for car owners, service station workers and persons studying the structure of the car, and examines the theoretical foundations of carburetion, design, features, possible methods repair and adjustment of carburetors K-126 and K-135 of the Leningrad plant "LENKARZ" (now "PEKAR"), installed on cars of the Gorky automobile plant and buses of the Pavlovsk automobile plant.

The brochure is intended for car owners, service station workers and people studying the structure of the car

Cand. tech. Sciences A.N. Tikhomirov

From the author

Carburetors of the K-126 series represent a whole generation of carburetors produced by the Leningrad carburetor plant "LENKARZ", which later became JSC "PEKAR" (St. Petersburg Carburetors), for almost forty years. They appeared in 1964 on legendary cars GAZ-53 and GAZ-66 simultaneously with the then new ZMZ-53 engine. These engines, Zavolzhsky motor plant replaced the famous GAZ-51 along with the single-chamber carburetor used on it.

A little later, from 1968, Pavlovsky bus factory began production of PAZ-672 buses, in the seventies a modification of PAZ-3201 appeared, later PAZ-3205, and all were equipped with an engine made on the basis of the same one that was used on trucks, but with additional elements. The power system did not change, and the carburetor was also, accordingly, of the K-126 family.

The impossibility of immediately completely switching to new engines led to the appearance in 1966 of the transitional GAZ-52 car with a six-cylinder engine. On them, in 1977, the single-chamber carburetor was also replaced by the K-126 with a corresponding replacement of the intake pipe. The K-126I was installed on the GAZ 52-03, and the K-126E on the GAZ 52-04. The only difference in carburetors concerns the different types of maximum speed limiters. Paired with carburetors K-126I, -E, -D, intended for the GAZ-52, a limiter was installed, which worked due to the high-speed pressure of air passing into the engine. The pneumatic centrifugal limiter of the K-126B or K-135 carburetor on ZMZ engines operates according to a signal from a centrifugal sensor mounted on the toe camshaft.

ZMZ-53 engines were improved and changed. The last major change occurred in 1985, when the ZMZ-53-11 appeared with a full-flow oil filtration system, a single-tier intake pipe, screw intake ports, an increased compression ratio and a K-135 carburetor. But the family has not been broken, the K-135 has all the body parts of the K-126 family and only some differences in the cross-sections of the jets. In these carburetors, measures were taken to bring the composition of the prepared mixture closer to the requirements of new times, and changes were made to meet more stringent toxicity standards. In general, the carburetor adjustments have shifted to a poorer side. The design of the carburetor took into account the introduction of an exhaust gas recirculation (EGR) system on the engines, adding a vacuum tap to the EGR valve. In the text we will not use the K-135 markings except in isolated cases, considering it simply one of the modifications of the K-126 series.
The natural difference in the engines on which the K-126 is installed is taken into account in the size of the metering elements. First of all, these are jets, although diffusers of different diameters can also be found. The changes are reflected in the index assigned to each carburetor and this must be remembered when trying to replace one carburetor with another. A summary table of the dimensions of the main metering elements of all modifications of the K-126 is given at the end of the book. Column “K-135” is valid for all modifications: K-135, K-135M, K-135MU, K-135X.

It should be remembered that the carburetor is only part of a complex complex called an engine. If, for example, the ignition system does not work properly, the compression in the cylinders is low, or the intake tract is leaky, then it is, at least, illogical to blame only the carburetor for “failures” or high fuel consumption. It is necessary to distinguish between defects related specifically to the power system, their characteristic manifestations during movement, and components that may be responsible for this. To understand the processes occurring in the carburetor, the beginning of the book is devoted to a description of the theory of regulation of spark internal combustion engines and carburetion.

Currently, Pavlovsk buses are practically the only consumers of eight-cylinder ZMZ engines. Accordingly, carburetors of the K-126 family are becoming less and less common in the practice of repair services. At the same time, the operation of carburetors continues to pose questions that require answers. The last section of the book is devoted to identifying possible malfunctions carburetors and methods for eliminating them. Do not expect, however, that you will find a universal “master key” to eliminate every possible defect. Assess the situation yourself, read what is said in the first section, “apply” it to your specific problem. Carry out a full range of work to adjust the carburetor components. The book is intended primarily for ordinary drivers and persons performing maintenance or repair of power systems in bus or car fleets. I hope that after studying the book they will no longer have questions regarding this family of carburetors.

PRINCIPLE OF OPERATION AND DEVICE OF THE CARBURETOR

1. Operating modes, ideal carburetor characteristics.

The power of internal combustion engines is determined by the energy contained in the fuel and released during combustion. To achieve more or less power, it is necessary, accordingly, to supply more or less fuel to the engine. At the same time, combustion of fuel requires an oxidizer—air. It is the air that is actually sucked into the engine pistons during the intake strokes. By using the gas pedal connected to the carburetor throttle valves, the driver can only limit the access of air to the engine or, on the contrary, allow the engine to fill to the limit. The carburetor, in turn, must automatically monitor the air flow entering the engine and supply a proportional amount of gasoline.

Thus, the throttle valves located at the outlet of the carburetor regulate the amount of the prepared mixture of air and fuel, and therefore the engine load. Full load corresponds to maximum throttle openings and is characterized by the greatest flow of combustible mixture into the cylinders. At “full” throttle the engine develops highest power, achievable at a given speed. For passenger cars the share of full loads in actual operation is small - about 10...15%. For trucks, on the contrary, full load modes occupy up to 50% of the operating time. The opposite of full load is idle. In relation to a car, this is the operation of the engine with the gearbox turned off, regardless of what the engine speed is. All intermediate modes (from idle to full load) fall under the definition of partial load.

A change in the amount of mixture passing through the carburetor also occurs at a constant throttle position in the event of a change in engine speed (the number of operating cycles per unit time). In general, load and rotation speed determine the operating mode of the engine.

A car engine operates in a huge variety of operating modes caused by changing road conditions or the desire of the driver. Each driving mode requires its own amount of engine power, each operating mode corresponds to a certain air flow and must correspond to a certain mixture composition. Mixture composition refers to the ratio between the amount of air and fuel entering the engine. Theoretically, complete combustion of one kilogram of gasoline will occur if slightly less than 15 kilograms of air are involved. This value is determined chemical reactions combustion and depends on the composition of the fuel itself. However, in real conditions it turns out to be more profitable to maintain the composition of the mixture, although close to the named value, but with deviations in one direction or another. A mixture in which there is less fuel than theoretically required is called lean; in which there is more - rich. For quantitative assessment, it is customary to use the excess air coefficient a, showing the excess air in the mixture:

a = Gв / Gт * 1о

where Gв is the air flow entering the engine cylinders, kg/hour;

GT — fuel consumption entering the engine cylinders, kg/hour;

1o - the estimated amount of air in kilograms required

for burning 1 kg of fuel (14.5…15).

For poor mixtures a > 1, for rich mixtures - a< 1, смеси с а =1 называются стехиометрическими.

The main output parameters of the engine are the effective power Ne (kW) and the specific effective fuel consumption g = Gm/Ne (g/kWh). Specific consumption is a measure of efficiency, an indicator of the perfection of the engine's operating process (the lower the value of ge, the higher the effective efficiency). Both parameters depend on both the quantity of the mixture and its composition (quality).
What mixture composition is required for each mode can be determined by special adjustment characteristics taken from the engine on a brake stand at fixed throttle positions and constant rotation speeds.
One of these characteristics is shown in Fig. 1.

Rice. 1. Adjustment characteristic for mixture composition: Engine ZMZ 53-18 n=2000 min’,P1,=68 kPa

The graph clearly shows that in this mode the maximum power is achieved with an enriched mixture a = 0.93 (such a mixture is usually called power), and the minimum specific fuel consumption, i.e. maximum efficiency, at lean a = 1.13 (the mixture is called economical).

It can be concluded that the appropriate control limits lie in the interval between the power and economical control points (indicated by an arrow in the figure). Beyond these limits, combustible mixture compositions are unprofitable, since working on them is accompanied by both a deterioration in efficiency and a drop in power. The increase in engine efficiency when the mixture is lean from power to economical is explained by an increase in the completeness of fuel combustion. With further depletion of the mixture, efficiency begins to deteriorate again due to a significant drop in power caused by a decrease in the combustion rate of the mixture. This should be remembered by those who, in the hope of reducing the fuel consumption of their engine, seek to limit the flow of gasoline into it.

For all partial load modes, economical mixture compositions are preferable, and working with economical mixtures will not limit our power. It should be remembered that power, which at a certain throttle position is achieved only with a power mixture, can also be obtained with an economy mixture, only with a slightly larger quantity (with a larger throttle opening). The leaner the mixture we use, the more it will be needed to achieve the same power. In practice, the power composition of the combustible mixture is organized only at full load.

By taking a series of control characteristics at different throttle positions, it is possible to construct the so-called optimal control characteristics, showing how the mixture composition should change when the load changes (Fig. 2).

Rice. 2. Characteristics of optimal regulation of a spark engine

Generally, perfect carburetor(if efficiency is the priority rather than toxicity, for example) should ensure a change in the composition of the mixture in accordance with line abc. Each point in section ab corresponds to an economical mixture composition for a given load. This is the longest part of the characteristic. At point b, a smooth transition to enriching the mixture begins, continuing until point c.

Any power value could be achieved using only power mixtures throughout the entire characteristic (dc line). However, running such mixtures at part loads does not make much sense, since there is a reserve of achieving the same power by simply opening the throttle and injecting more of the still economical mixture. Enrichment is really only necessary at full throttle openings, when the reserves for increasing the amount of mixture have been exhausted. If enrichment is not carried out, then the characteristic will “stop” at point b and the increase in power ANt will not be achieved. We will get approximately 90% of the possible power.

2. Carburation, formation of toxic components

In addition to dosing fuel, an important task facing the carburetor is organizing the mixing of fuel with air. The fact is that combustion requires not liquid, but gasified, evaporated fuel. The first stage of preparing the mixture takes place directly in the carburetor - atomizing the fuel, crushing it into the smallest possible droplets.

The higher the quality of atomization, the more evenly the mixture is distributed among individual cylinders, the more homogeneous the mixture in each cylinder, the higher the speed of flame propagation, power and efficiency while reducing the amount of incomplete combustion products. The complete evaporation process does not have time to occur in the carburetor, and part of the fuel continues to move along the intake pipe to the cylinders in the form of a liquid film. The design of the intake pipe thus has a fundamental impact on the engine output. The heat required to evaporate the film is specially selected and supplied to the air-fuel mixture from the coolant.

It should be remembered that the values of the optimal mixture compositions determined by the characteristics may vary depending on various factors. For example, all of them are determined under the normal thermal state of the engine. The better the fuel is evaporated by the time it enters the cylinders, the more lean mixture compositions can achieve both maximum efficiency and maximum power. If the carburetor prepares an economical mixture for a warm engine, then at a low temperature (while warming up, with a faulty thermostat or its absence) this mixture will turn out to be leaner than necessary, the specific consumption will be sharply increased, and the operation will be unstable. The “colder” the engine, the richer the mixture must be supplied to it.

To a great extent, the composition of the air-fuel mixture determines the toxicity of exhaust gases. It should be remembered that car engine internal combustion can never be completely harmless. As a result of fuel combustion, in the most favorable outcome, carbon dioxide CO2 and water H2O are formed. However, they are not toxic, i.e. poisonous and do not cause any disease in humans.
First of all, incompletely burned components are undesirable. exhaust gases, the most important and most frequent components which are carbon monoxide (CO), unburned or only partially burned hydrocarbons (CH), soot (C) and nitrogen oxides (NO). All of them are toxic and dangerous to the human body. In Fig. Figure 3 shows typical curves of changes in the concentrations of the three most well-known components depending on the composition of the mixture.

Rice. 3. Dependence of emissions of toxic components on the mixture composition of a gasoline engine

The concentration of carbon monoxide CO naturally increases with the enrichment of the mixture, which is explained by the lack of oxygen for the complete oxidation of carbon to CO2. The increase in the concentrations of unburned CH hydrocarbons in the region of rich mixtures is explained by the same reasons, and when depleted beyond a certain limit (dashed zone in the figure), a sharp rise in the CH curve is due to sluggish combustion and even sometimes misfiring of such lean mixtures.

One of the most toxic components in exhaust gases is nitrogen oxides, NOx. This symbol is assigned to a mixture of nitrogen oxides NO and NOa, which are not products of fuel combustion, but are formed in engine cylinders in the presence of free oxygen and high temperature. The maximum concentration of nitrogen oxides occurs at mixture compositions that are closest to economical, and the amount of emissions increases with increasing engine load. The danger of exposure to nitrogen oxides lies in the fact that poisoning of the body does not appear immediately, and there are no neutralizing agents.
At idle modes, where the toxicity test familiar to all motorists is carried out, this component is not taken into account, since the engine cylinders are “cold” and NOx emissions in this mode are very small.

3. Main carburetor metering system

K-126 carburetors are designed for multi-cylinder engines trucks, which have a very large share of work at full load. All cylinders in such engines, as a rule, are divided into groups, which are fed by separate carburetors or, as in the case of the K-126, by separate chambers of one carburetor. The division into groups is organized by manufacturing an inlet pipe with two independent groups of channels. Cylinders included in one group are selected so that excessive air pulsations in the carburetor and distortion of the mixture composition.

For eight-cylinder V-shaped ZMZ engines, with the cylinder operating order adopted for them, a uniform alternation of cycles in two groups will be observed when the cylinders operate one after another (Fig. 4 A). From Fig. 4 B it is clear that with such a division the channels in the intake pipe must intersect, i.e. be carried out on different levels. This was the case on the ZMZ-53 engine: the intake pipe was two-tiered.

Rice. 4. Division diagram for eight-cylinder engines

into groups with uniform alternation:

a) according to the order of work; b) by location on the engine.

On ZMZ 53-11 engines, among other changes, the casting of the intake pipe was simplified, making it single-tier. From now on, the channels in the groups do not intersect; the cylinders of the left half-block belong to one group, and the cylinders of the right half-block to the second (Fig. 5).

Rice. 5. Scheme of dividing eight-cylinder engines into groups with a single-tier intake pipe:

a) according to the order of work; b) by location on the engine.

1 - first carburetor chamber, 2 - second carburetor chamber

The cheaper design had a negative impact on the operating conditions of the carburetor. The uniformity of the alternation of cycles in each of the groups was disrupted, and along with it the uniformity of air intake pulses in the carburetor chambers. The engine becomes prone to scattering of the mixture composition in separate cylinders and successive cycles. With a certain average value, which is prepared by the carburetor, in individual cylinders (or cycles of the same cylinder), the mixture can be either richer or leaner. Consequently, when the average mixture composition deviates from the optimal composition in some cylinders, the mixture is more likely to go beyond the ignition limits (the cylinder turns off). This situation can be smoothed over partly due to the presence of a film of unevaporated fuel in the intake pipe, which “creeps” towards the cylinders relatively slowly.

Despite all the listed features, the K-126 vertical carburetor, with a falling flow, with parallel opening of the throttles, is actually two identical carburetors assembled in one body, where a common float chamber is located. Accordingly, it has two main dosing systems operating in parallel. In Fig. Figure 6 shows a diagram of one of them. It has a main air channel, which includes a small diffuser (spray) 16, installed in a narrow section of the main large diffuser 15, and a mixing chamber with a throttle 14. The throttle is a plate mounted on an axis, by turning which you can adjust the flow area of the mixing chamber , and therefore air flow. Parallel opening of the throttles means that in each mixing chamber the throttle valves are installed on a common axis, the drive of which is organized from the gas pedal. By acting on the pedal, we open both throttles at the same angle, which ensures equality of air passing through the carburetor chambers.

The main metering system performs the main task of the carburetor - dosing fuel in proportion to the air entering the engine. It is based on a diffuser, which is a local narrowing of the main channel. In it, due to the relative increase in air speed, a vacuum (pressure below atmospheric) is created, depending on the air flow. The vacuum generated in the diffusers is transmitted to the main fuel jet 11, located at the bottom of the float chamber.

Rice. 6. Diagram of the main metering system of the K-126 carburetor: 1 - inlet air pipe; 2 - fuel filter plug; 3 - float chamber cover; 4 - fuel filter; 5 — fuel inlet from the fuel pump; 6 — float chamber valve; 7 — float chamber body; 8 — float; 9 — float chamber valve needle; 10 — main fuel jet plug; 11 — main fuel jet; 12 — main air jet; 13 - emulsion tube; 14 — throttle valve; 15 - large diffuser; 16 — small diffuser; 17 — economizer sprayer; 18 — accelerator pump nozzle; 19 — air inlet

They are accessed through threaded plugs 10 screwed into the wall of the float chamber housing 7. A nozzle is any calibrated hole for dosing fuel, air or emulsion. The most important of them are made in the form of separate parts inserted into the housing on a thread (Fig. 7). For any nozzle, not only the flow area of the calibrated part is fundamental, but also the ratio between the length and diameter of the calibrated part, the angles of the inlet and outlet chamfers, the quality of the edges and even the diameters of the uncalibrated parts.

The required proportion of fuel to air is ensured by the ratio of the cross-sectional area of the fuel nozzle and the cross-section of the diffuser. Increasing the jet will lead to a richer mixture in the entire range of modes. The same effect can be achieved by reducing the flow area of the diffuser. The cross-sections of the carburetor diffusers are selected based on two conflicting requirements: the larger the diffuser area, the higher the power can be achieved by the engine, and the worse the quality of fuel atomization due to more low speeds air.

Rice. 7. Fuel jet diagram

l-length of the calibrated part

Considering that the large diffusers are plug-in and the dimensions are unified for all modifications of the K-126 (including passenger cars), there is no mistake when assembling. A diffuser with a diameter of 24 mm can easily be installed in place of a standard diffuser with a diameter of 27 mm.
To further improve the quality of atomization, a scheme with two diffusers (large and small) was used. Small diffusers are separate parts inserted into the middle part of large diffusers. Each of them has its own atomizer, connected by a channel to a hole in the body from which fuel is supplied.

Be careful about the channel orientation!

Each jet has a number stamped on it indicating the flow rate in cm3/min. This marking is adopted on all PEKAR carburetors. The test is carried out using a specialized flowing device and means the amount of water in cm3 passing through the nozzle in the forward direction per minute at a pressure of the liquid column of 1000 ± 2 mm. Deviations in the throughput of the jets from the standard should not exceed 1.5%.

Only a specialized enterprise with the appropriate equipment can truly produce a jet. Unfortunately, many people undertake the production of repair jets and, as a result, one cannot be completely sure that the main fuel jet marked “310” will not actually be size “285”. Based on experience, it is better to never change factory jets, especially since there is no particular need for this. The jets do not wear out noticeably even with long-term use, and a decrease in the cross-section due to resins deposited on the calibrated part is unlikely with modern gasoline.

In a carburetor, to maintain a stable pressure drop across the fuel nozzle, the fuel level in the float chamber must remain constant. Ideally, the fuel should be located at the level of the edge of the nozzle. However, to prevent spontaneous leakage of gasoline from the nozzle during possible tilting of the car, the level is maintained 2...8 mm lower. In most operating modes (especially a truck, which has a large share of full loads), such a decrease in level cannot have any noticeable effect on the flow of gasoline. The vacuum in the diffuser can reach 10 kPa (which corresponds to a 1300 mm “gasoline” column) and, naturally, lowering the level by a few millimeters does not change anything. We can assume that the composition of the mixture prepared by the carburetor is determined only by the ratio of the areas of the fuel nozzle and the narrow cross-section of the diffuser. Only at the lightest loads, when the vacuum in the diffusers drops to less than 1 kPa, do errors in the fuel level begin to have an effect. To eliminate fluctuations in the fuel level in the float chamber, a float mechanism is installed in it. It is all assembled on the carburetor cover, and the fuel level is adjusted automatically by changing the flow area of valve 6 (Fig. 8) by valve needle 5, actuated by tongue 4 on the float holder.

Rice. 8. Carburetor float mechanism:

1 — float; 2 — float travel limiter; 3 — float axis; 4 — level adjustment tongue; 5 — valve needle; 6 - valve body; 7 - sealing washer; A is the distance from the plane of the cover connector to the top point of the float; B - gap between the end of the needle and the tongue

As soon as the fuel level drops below the set level, the float, lowering along with it, will lower the tongue, which will allow needle 5, under the influence of the fuel pressure created by the fuel pump, and its own weight, to lower and let a larger amount of gasoline into the chamber. It can be seen that fuel pressure plays a certain role in the operation of the float chamber. Almost all gasoline pumps must create a gasoline pressure of 15...30 kPa. Deviations in a large direction can, even with correct adjustments of the float mechanism, create fuel leakage through the needle.

To control the fuel level, earlier modifications of the K-126 had an inspection window on the wall of the float chamber housing. Along the edges of the window, approximately along its diameter, there were two tides that marked the line of normal fuel level. In the latest modifications there is no window, and the normal level is marked with a mark 3 (Fig. 9) on the outside of the body.

Rice. 9. View of the carburetor from the fittings side: 1 - channel into the over-diaphragm limiter; 2 — plugs of the main fuel jets; 3 - risk of fuel level in the float chamber; 4 — supply channel from the fuel pump; 5 - traction; 6 — vacuum tap for the recirculation valve; 7 - channel sub-membrane chamber limiter

To increase the reliability of locking, a small polyurethane washer 7 is placed on the valve needle 5 (Fig. 8), which retains elasticity in gasoline and reduces the locking force several times. In addition, due to its deformation, the vibrations of the float that inevitably occur when the car is moving are smoothed out. If the washer is destroyed, the tightness of the assembly is immediately irreversibly compromised.

The float itself can be brass or plastic. The reliability (tightness) of both is quite high, unless you deform it yourself. To prevent the float from knocking on the bottom of the float chamber when there is no gasoline in it (which is most likely when operating dual-fuel gas-cylinder cars), the float holder has a second antenna 2, resting on a stand in the body. By bending it, the needle stroke is adjusted, which should be 1.2 ... 1.5 mm. On a plastic float this tendril is also plastic, i.e. it cannot be bent. The needle stroke is not adjustable.

A simple carburetor, which has only a diffuser, a spray nozzle, a float chamber and a fuel nozzle, is able to maintain the mixture composition approximately constant throughout the entire air flow range (except for the smallest). But to get as close as possible to ideal characteristics dosing, as the load increases, the mixture should be leaner (see Fig. 2, section ab). This problem is solved by introducing a mixture compensation system with pneumatic fuel braking. It includes an emulsion well installed between the fuel nozzle and the sprayer with an emulsion tube 13 and an air nozzle 12 placed in it (see Fig. 6).

The emulsion tube is a brass tube with a closed bottom end, having four holes at a certain height. It is lowered into the emulsion well and pressed from above by an air jet screwed into the thread. With increasing load (vacuum in the emulsion well), the fuel level inside the emulsion tube drops and, at a certain value, is below the holes. Air begins to flow into the atomizer channel, passing through the air nozzle and holes in the emulsion tube. This air mixes with the fuel before leaving the atomizer, forming an emulsion (hence the name), facilitating further atomization in the diffuser. But the main thing is that the supply of additional air reduces the level of vacuum transmitted to the fuel nozzle, thereby preventing excessive enrichment of the mixture and giving the characteristic the necessary “slope”. Changing the cross-section of the air jet will have virtually no effect at low engine loads. At high loads (high air flows), increasing the air jet will provide a greater leanness of the mixture, and decreasing it will provide a richer mixture.

4. Idle system

At low air flow rates, which are present in idle modes, the vacuum in the diffusers is very small. This leads to instability in fuel dosing and a high dependence of its consumption on external factors, for example, fuel level. Under the throttle valves in the intake pipe, on the contrary, it is in this mode that the vacuum is high. Therefore, at idle and at low throttle opening angles, the fuel supply to the atomizer is replaced by a supply under the throttle valves. For this purpose, the carburetor is equipped with a special idle speed system (IAC).

The K-126 carburetors use a CXX scheme with throttle atomization. At idle, air enters the engine through a narrow annular gap between the walls of the mixing chambers and the edges of the throttle valves. The degree of closure of the throttles and the cross-section of the cracks formed are regulated by stop screw 1 (Fig. 10). Screw 1 is called the "quantity" screw. By turning it in or out, we regulate the amount of air entering the engine and thereby change the engine idle speed.

The throttle valves in both chambers of the carburetor are installed on the same axis and the “quantity” thrust screw regulates the position of both throttles. However, inevitable errors in the installation of throttle plates on the axle lead to the fact that the flow area around the throttles may be different. At large opening angles, these differences are not noticeable against the background of large flow sections. At idle, on the contrary, the slightest differences in the throttle settings become fundamental. The inequality of the flow sections of the carburetor chambers causes different air flow through them. Therefore, in carburetors with parallel opening of the throttles, one screw for adjusting the mixture quality cannot be installed. Personal adjustment is required for the cameras using two “quality” screws.

Rice. 10. Carburetor adjustment screws:

1 - thrust screw of the throttle valves (quantity screw); 2 - mixture composition screws (quality screws); 3 - limit caps

In the family under consideration there is one K-135X carburetor, in which the idle system was common to both chambers. There was only one “quality” adjusting screw and was installed in the center of the mixing chamber housing. From it, fuel was supplied into a wide channel, from which it diverged into both chambers. This was done to organize the EPH system, a forced idling economizer. The solenoid valve blocked the common idle speed channel and was controlled by the electronic unit using signals from the ignition distributor sensor (rotation speed signal) and from the limit switch installed at the “quantity” screw. The modified screw with platform is visible in Fig. 14. Otherwise, the carburetor is no different from the K-135.

The K-135X is an exception and, as a rule, carburetors have two independent idle systems in each carburetor chamber. One of them is shown schematically in Fig. 11. Fuel is taken from them from the emulsion well 3 of the main metering system after the main fuel jet 2. From here, the fuel is supplied to the idle fuel jet 9, screwed vertically into the float chamber body through the cover so that it can be unscrewed without disassembling the carburetor. The calibrated part of the jets is made on the toe, below the sealing belt, which rests against the body when screwed. If there is no tight contact with the belt, the resulting gap will act as a parallel jet with a corresponding increase in the cross-section. On older carburetors, the idle fuel jet had an extended nose that went down to the bottom of its well.

After leaving the fuel nozzle, the fuel meets air supplied through the idle air nozzle 7, screwed under the plug 8. The air nozzle is necessary to reduce the vacuum on the idle fuel nozzle, form the required idle characteristics and prevent spontaneous leakage of fuel from the float chamber when stopped. engine
The mixture of fuel and air forms an emulsion, which flows down through channel 6 to the throttle body. Next, the flow is divided: part goes to the transition hole 5 just above the throttle edge, and the second part goes to the “quality” adjusting screw 4. After adjustment with the screw, the emulsion is discharged directly into the mixing chamber after the throttle valve.

On the carburetor body, “quality” screws 2 (Fig. 10) are located symmetrically in the throttle body in special niches. To prevent the owner from violating the adjustments, the screws can be sealed. To do this, plastic caps 3 can be put on them, limiting the rotation of the adjusting screws.

Rice. 11. Diagram of the idle system and transition system: 1 - float chamber with a float mechanism; 2 — main fuel jet; 3 - emulsion well with emulsion tube; 4 — “quality” screw; 5—via hole; 6 — fuel supply channel to the openings of the idle system; 7 — idle air jet; 8 — air jet plug; 9 — idle fuel jet; 10 — inlet air pipe

5. Transition systems

If the throttle of the primary chamber is smoothly opened, the amount of air passing through the main diffuser will increase, but the vacuum in it for some time will still be insufficient for fuel to flow out of the atomizer. The amount of fuel supplied through the idle system will remain unchanged, since it is determined by the vacuum behind the throttle. As a result, the mixture will begin to become leaner during the transition from idle to operation of the main metering system, until the engine stops. To eliminate the “failure”, transition systems are organized that operate at small throttle opening angles. They are based on transition holes located above the upper edge of each throttle when they are positioned against the stop in the “quantity” screw. They act as additional air jets of variable cross-section that control the vacuum of the idle fuel jets. At minimum idle speed, the transition hole is located above the throttle in an area where there is no vacuum. Gasoline does not leak through it. When the throttle moves up, the holes are first blocked due to the thickness of the damper, and then enter the zone of high throttle vacuum. High vacuum is transmitted to the fuel nozzle and increases fuel flow through it. Gasoline begins to leak not only through the outlet holes after the “quality” screws, but also from the transition holes in each chamber.

The cross-section and location of the vias are chosen so that when the throttle is opened smoothly, the composition of the mixture should remain approximately constant. However, to solve this problem, one via, which is available on the K-126, is not enough. Its presence only helps to smooth out the “failure” without eliminating it completely. This is especially noticeable on the K-135, where the idle system is made leaner. In addition, the operation of the transition systems in each of the chambers is influenced by the identity of the installation of the throttle plates on the axles. If one of the throttles is higher than the second, then it begins to close the transition hole earlier. In the other chamber, and therefore in the group of cylinders, the mixture may remain lean. Again, the fact that for a truck the operating time at low loads is short helps to smooth out the low quality of transition systems. Drivers “step over” this mode by immediately opening the throttle to a large angle. To a large extent, the quality of the transition to load depends on the operation of the accelerator pump.

6. Economizer

The economizer is a device for supplying additional fuel (enrichment) at full load conditions. Enrichment is necessary only at full throttle openings, when the reserves for increasing the amount of mixture have been exhausted (see Fig. 2, section bc). If the enrichment is carried out, then the characteristic will “stop” at point b and the increase in power ANe will not be achieved. We will get approximately 90% of the possible power.

In the K-126 carburetor, one economizer serves both carburetor chambers. In Fig. Figure 12 shows only one camera and its associated channels.
Economizer valve 12 is screwed into the bottom of a special niche in the float chamber. There is always gasoline above it. In the normal position, the valve is closed, and in order to open it, a special rod 13 must be pressed on it. The rod is fixed to a common bar 1 together with the piston of the accelerator pump 2. Using a spring on the guide rod, the bar is held in the upper position. The bar is moved by a drive lever 3 with a roller, which is turned by a rod 4 from the throttle drive lever 10. The drive adjustments should ensure that the economizer valve is activated when the throttles are opened by approximately 80%.

From the economizer valve, fuel is supplied through channel 9 in the carburetor body to the nozzle block. The K-126 nozzle block combines two nozzles of economizer 6 and accelerator pump 5 (for each carburetor chamber). The nozzles are located above the fuel level in the float chamber and for gasoline to flow through them, it must rise to a certain height. This is only possible in modes when there is a vacuum at the nozzle ends. As a result, the economizer supplies gasoline only when the throttles are fully open and the rotation speed is increased, i.e. performs partly the functions of an econostat.
The higher the rotation speed, the greater the vacuum created at the nozzles, and the greater the amount of fuel supplied by the economizer.

Rice. 12. Diagram of the economizer and accelerator pump:

1 — drive strip; 2 — accelerator pump piston; 3 - drive lever with roller; 4 - traction; 5 — accelerator pump nozzle; 6 — economizer sprayer; 7 - discharge valve; 8 — accelerator pump fuel supply channel; 9 — economizer fuel supply dripping; 10 — throttle lever; 11 — inlet valve; 12 — economizer valve; 13 — economizer pressure rod; 14 - guide rod

7. Acceleration pump

All the systems described above ensure engine operation in stationary conditions, when operating modes do not change or change smoothly. When you press the gas pedal sharply, the fuel supply conditions are completely different. The fact is that the fuel enters the engine cylinders only partially evaporated. Some of it moves along the intake pipe in the form of a liquid film, evaporating from the heat supplied to the intake pipe from the coolant circulating in a special jacket at the bottom of the intake pipe. The film moves slowly and final evaporation can occur already in the engine cylinders. With a sharp change in the throttle position, the air almost instantly takes on a new state and reaches the cylinders, which cannot be said about the fuel. The part of it that is enclosed in the film cannot quickly reach the cylinders, which causes some delay - a “failure” when the throttles are opened sharply. It is aggravated by the fact that when the throttles are opened, the vacuum in the intake pipe drops, and at the same time the conditions for evaporation of gasoline worsen.

To eliminate the unpleasant “failure” during acceleration, so-called accelerator pumps are installed on carburetors - devices that supply additional fuel only during sudden throttle openings. Of course, it will also largely turn into a fuel film, but with more gasoline, the “failure” can be smoothed out.

K-126 carburetors use a mechanical piston-type accelerator pump, which supplies fuel to both chambers of the carburetor regardless of air flow (Fig. 12). It has a piston 2 moving in the discharge chamber, and two valves - inlet 11 and discharge 7, located in front of the nozzle block. The piston is fixed to a common bar 1 together with the economizer pressure rod. The piston moves upward during the suction stroke (when the throttle is closed) under the action of a return spring, and when the throttle is opened, the bar with the piston moves down under the action of lever 3, driven by rod 4 from throttle lever 10. In the first designs of the K-126, the piston did not have a special seal and had inevitable leaks during operation. The modern piston has a rubber sealing collar that completely isolates the discharge cavity.

During the suction stroke, under the action of the spring, piston 2 rises and increases the volume of the discharge cavity. Gasoline from the float chamber through the inlet valve 11 freely passes into the discharge chamber. The discharge valve 7 in front of the sprayer closes and does not let air into the discharge chamber.

When the throttle drive lever 10 is sharply turned, rod 4 turns lever 3 with a roller on the axis, which presses bar 1 with piston 2. Since the piston is connected to the bar through a spring, in the first moments there is no movement of the diaphragm, but only compression of the spring under the bar, since gasoline filling the chamber cannot leave it quickly. Next, the already compressed piston spring begins to squeeze gasoline out of the discharge chamber to the atomizer 5. The discharge valve does not prevent this, and the inlet valve 11 blocks possible fuel leakage back into the float chamber.
The injection is thus determined by the piston spring, which must, at a minimum, overcome the friction of the piston and its cuff against the walls of the discharge chamber. Subtracting this force, the spring determines the injection pressure and implements continued fuel injection for 1...2 seconds. The injection ends when the piston lowers to the bottom of the injection chamber. Further movement of the bar only compresses the spring.

8. Starting device

No matter how well the listed carburetor systems are configured, its operation cannot be considered complete if measures are not taken to ensure the proper composition of the mixture when starting a cold engine and warming it up. The peculiarity of a cold start is that the resistance to turning the crankshaft due to thick oil is high, the engine turns over with low frequency rotation, vacuum in intake system is small, and gasoline evaporation is practically absent.
For a reliable cold start in conditions of poor fuel volatility, creating the required mixture composition is possible only by repeatedly increasing the amount of gasoline supplied to the engine.
A significant part of it will still not evaporate, but a larger amount of gasoline will produce a larger amount of vapor, which, when mixed with air, forms a mixture that can ignite.

Cold start creation is extremely rich mixture is carried out using an air damper 7 installed in the air channel above the diffusers 5 (Fig. 13). The air damper is fully closed in the cocked position. Air is forced to pass into the engine through two air valves 6, overcoming the resistance of the springs. As a result, an increased vacuum is formed under the damper, disproportionate to the actual air flow through the carburetor. The amount of air remains practically unchanged, but at the end of the nozzles of the main dosing system, the increased vacuum causes increased flow of gasoline. The greater the force of the air valve springs, the higher the vacuum and the greater the enrichment created during the start-up mode.

However, for a reliable start-up, enriching the mixture alone is not enough. To cold engine could work independently, the amount of rich mixture supplied should also be increased. Otherwise, the work done in the engine cylinders will be insufficient to overcome the increased resistance to turning of all engine mechanisms.

Rice. 13. Diagram of the starting device of the K-126 carburetor: 1 - float mechanism; 2 — main fuel jet; 3 - emulsion well; 4 — throttle body; 5 — diffusers of the main dosing system; 6 — air valve; 7 — air damper; A - throttle opening

To increase the amount of mixture on a cocked trigger mechanism, in addition to closing the air damper, simultaneous opening of the throttle valves is provided. The amount of throttle opening A determines the amount of mixture supplied to the engine.

Rice. 14. Adjusting the opening angle of the throttle valves when closed

air damper (cold engine start):

1 — throttle lever; 2 - traction; 3 — adjustment bar; 4 — accelerator pump drive lever; 5 — air damper drive lever; 6-axis air damper

Two main elements - the air damper and the opener - make it possible to ensure the first stage of a cold start, i.e. the start itself and the first few revolutions of the engine shaft. After the rotation speed has increased for more than 1000 rpm, the vacuum in the intake system increases sharply, a high temperature is created in the engine cylinders and the mixture supplied by the starting device becomes too rich.

If measures are not taken to reduce the enrichment, the engine will most likely stop within a few seconds. The driver must remove excessive enrichment by pushing down the starter drive button (the “choke” button). The air damper opens slightly and air begins to flow not only through the air valves, but also around. At the same time, there is a decrease in the slightly open throttle and a corresponding decrease in the supply of the combustible mixture and the rotation speed. Regulation of the mixture in the warm-up mode is completely entrusted to the driver, who must carefully adjust the position of the “choke” handle in order to prevent both excessive enrichment and excessive leanness of the mixture.

All control of the starting device is carried out from one lever of the air damper drive 5 (Fig. 14). The driver, pulling out the starting device drive handle in the cabin, turns lever 5 counterclockwise, and thereby cocks the entire starting mechanism. The axis of the air damper 6, connected to the lever 5, rotates and closes it. When turning, one arm on lever 5 slides along the adjustment bar 3 and. turns lever 4 of the accelerator pump drive through a certain angle. At the same time, rod 2 through lever 1 slightly opens the throttle valves, increasing the flow area for the mixture. The amount of throttle opening is regulated by moving the adjusting bar 3. To increase the opening, the bar should be moved towards lever 5.

9. Engine speed limiter

K-126 carburetors are designed for truck engines with increased load conditions. This is not a whim of the drivers, it’s just that in order to move, accelerate, and lift such a heavy car uphill, more power is needed. As engine speed increases, engine power naturally increases, but wear of parts in the cylinder-piston group also naturally increases. To prevent increased wear, truck engines are usually limited in terms of crankshaft rotation speed. Regulation is carried out by changing the flow area of the intake tract, and can be done in two ways: using special regulator valves, or the carburetor throttle valves themselves.

The limiter design includes a special stabilizing device that prevents the regulator damper from opening.
Separate maximum speed limiters for engines with carburetors K-126I, -E are used on six-cylinder GAZ-52 engines. The limiter is produced in the form of a separate spacer, which is mounted between the carburetor and the engine intake pipe (Fig. 15). Under K-126, the limiter has two chambers that coincide with the carburetor chambers. In each of them, the main parts are a damper and a spring. The dampers are installed eccentrically to the center line of the carburetor and at a certain initial angle.

When the engine is running, the regulator flaps are affected by the high-speed pressure of the combustible mixture and the vacuum present in the throttle cavity. The total moment of forces acting on the dampers will tend to close them. This closing is counteracted by the limiter spring 14. Rotation of the dampers towards the cover can only occur if the total moment of forces acting on the dampers increases and becomes greater than the spring moment. In order for the dampers to close relatively smoothly, the arm of application of the spring force is made variable.

Rice. 15. Pneumatic speed limiter: 1 - piston; 2 — rod; 3 - roller; 4 — bracket; 5 - axis; 6 — regulator dampers; 7 - screw; 8 - nut; 9 — felt filter; 10 — spring clip; 11 - cam; 12 — body; 13 — belt traction; 14 — limiter spring with the carburetor throttle closed.

With the carburetor throttle closed. The device consists of rod 2, piston 1 and well, the rod is connected to the regulator throttle. Air enters the well through a felt filter 9, secured in the housing with a washer and a spring clamp 10. If, with the carburetor throttle valves closed, large vacuums arise above the regulator valve, then it will also be closed, at partial loads without “throwing”.

The K-126 carburetor for eight-cylinder engines has a built-in pneumatic centrifugal maximum speed limiter. This limiter consists of two main components: a command pneumatic centrifugal sensor and a membrane actuator (Fig. 16)

The pneumatic centrifugal sensor consists of a stator housing and a rotor 3 located inside. The sensor is mounted on the engine timing cover, and the rotor is rigidly connected to the camshaft. The rotor valve mechanism is located perpendicular to the axis of rotation. Valve 4 simultaneously plays the role of a weight of the centrifugal regulator. The internal cavity of the rotor communicates with one output of the sensor, and the cavity of the housing communicates with the other. Communication between the two formed chambers occurs only through the valve seat when it is in the open position. mechanism 1 is attached with three screws to the carburetor mixing chamber housing. It consists of a membrane with a rod 2, a double-armed lever 8 and a spring 7.
The double-arm lever is secured with a nut to the axis of the throttle valves 11. The spring, engaged on one arm of the lever, is put with the other end onto a pin fixed in the actuator body. To adjust the spring preload, the pin can be installed in any of the four sockets located in the housing. The membrane rod is hooked to the other arm of the lever. The cavities inside the actuator under and above the membrane have outputs that are connected by copper tubes 6 to the corresponding outputs on the centrifugal sensor.

Rice. 16. Diagram of a pneumatic centrifugal speed limiter: 1 - limiter actuator; 2 - membrane with rod; 3 — rotor of the centrifugal sensor; 4 - valve; 5 — sensor adjustment screw; 6 — connecting tubes; 7 — limiter spring; 8 — double-arm lever; 9 — channel into the submembrane cavity; 10 — jets in the channels of the supra-membrane cavity; 11 - throttle axis; 12 — vacuum supply channel; 13 — fork connection; 14 — throttle drive lever

The carburetor throttle valve shaft is mounted in roller bearings to reduce friction and allow rotation by a relatively weak diaphragm mechanism. To seal the cavity of the actuator, the axis of the throttle valves is sealed with a rubber seal, pressed against the chamber walls by a spacer spring. At the second end of the axis there is a throttle drive lever 14, mounted on its short axis. The connection of the drive axis with the axis of the fork-type throttles 13 is made so that, under the action of the membrane limiter mechanism, the throttles can be closed regardless of the position of the drive lever.

Thus, the name “drive lever” is conditional. He does not actually open the throttles (just like a person pressing the drive pedal), but only gives “permission” to the throttles to open. The actual opening of the carburetor throttles is carried out by a spring in the actuator housing, provided that the regulator has not yet entered into operation (the rotation speed has not reached the limit value).

The cavity above the membrane is connected by a channel simultaneously with the space under and above the throttle valves through two jets 10. Through them there is a constant flow of air from the space above the throttle to the space behind the throttle. The resulting vacuum entering the above-membrane cavity turns out to be lower than the purely throttle vacuum, but sufficient to overcome the spring force and move the membrane upward. The cavity of the actuator under the membrane, channel 9, communicates with the inlet neck of the carburetor. The centrifugal sensor is connected to the membrane actuator in parallel.

At frequencies below the threshold (3200 min"1), the valve in the sensor rotor is pulled away from the seat by a spring. Through a hole in the seat, the outputs from the sensor communicate with each other and bypass the above- and submembrane cavities. The vacuum coming from under the throttle through channel 12 is extinguished by air coming from the carburetor neck through the centrifugal sensor. The membrane is not able to overpower the spring that opens the throttle. When maximum speed is reached, the centrifugal forces acting on valve 4 overcome the spring force and press the valve to the seat. The outputs of the centrifugal sensor are disconnected, and the membrane chamber remains under the influence of different vacuum on both sides of the membrane. The membrane, together with the rod, moves upward and closes the throttles, despite the fact that the driver continues to press or hold down the drive lever 14.

MAINTENANCE AND ADJUSTMENT OF THE CARBURETOR

The creation of a reliable design is ensured, on the one hand, by designers who provide solutions with high operational reliability and maintainability, and on the other hand, by competent operation of devices to maintain proper technical condition. K-126 carburetors are very simple in design, moderately reliable and require minimal maintenance when used correctly.

Most malfunctions occur either after unqualified intervention in the adjustments or in the event of clogging of the dosing elements with solid particles. Among the types of maintenance, the most common are flushing, adjusting the fuel level in the float chamber, checking the operation of the accelerator pump, adjusting the starting system and idle system.
Another maintenance option is when intervention in the carburetor occurs only after an obvious malfunction is detected. In other words - repair. In this case, only those components that have been previously identified as the most likely culprits of malfunctions can be disassembled.

Maintenance and adjustment of the carburetor does not always require its removal from the engine. By removing the air filter housing, you can already provide access to many carburetor devices. If you still decide to carry out a full maintenance of your carburetor, then it is better to do this by removing it from the car.

Removing the carburetor

After the air filter housing has been removed, it begins by disconnecting the gasoline supply hose from the carburetor, the vacuum sampling tubes for the vacuum ignition timing regulator and the recirculation valve (if equipped), two copper tubes from the limiter and the choke control rod. The rod is secured with two screws: one on the bracket secures the braid, and the second on the air damper drive lever secures the rod itself. To disconnect the throttle valve drive rod, it is more advisable to unscrew the nut on the throttle control lever, which secures the strut with a spherical head on the inside.

The stand will be removed from the lever and will remain on the rod coming from the driver's pedal. Next, all that remains is to unscrew the four nuts securing the carburetor to the intake pipe, remove the washers so that they do not accidentally fall in, and remove the carburetor from the studs. You should separate the gasket underneath so that it does not stick, but remains on the inlet pipe. Next, you can put the carburetor aside and be sure to securely plug the holes on the inlet pipe with some rag. This operation will not take much time, but will prevent many troubles associated with anything (such as nuts) getting inside the engine.

Carburetor flushing

Although the K-126, like all carburetors, is demanding on cleanliness, there is no need to overuse frequent flushing. When disassembling, it is easy to carry dirt inside the carburetor or break worn-in connections or seals. External washing is done with a brush using any liquid that dissolves oily deposits. This can be gasoline, kerosene, diesel fuel, their analogues, or special washing liquids dissolved in water. The latter are preferable because they are not so aggressive to human skin and are not a fire hazard. After washing, you can blow air over the carburetor, or simply blot it lightly with a clean cloth to dry the surface. As already mentioned, the need for this operation is small, and there is no need to carry out washing just for the sake of shine on the surfaces. To flush the internal cavities of the carburetor, you will need to at least remove the float chamber cover.

Removing the top cover

you need to start by disconnecting the economizer drive rod and accelerator pump. To do this, undo the cotter pin and remove it from the hole in the lever. top end rod 2 (see Fig. 14). Then you should unscrew the seven screws securing the float chamber cover and remove the cover without damaging the gasket. To make the cover easier to remove, press the choke lever with your finger until it is vertical. In this case, it appears opposite the recess in the body and does not cling to it. Move the lid to the side and only then turn it over the table so that the screws fall out (if you did not remove them immediately). Assess the quality of the print and the general condition of the gasket. It should not be torn and a clear imprint of the body should be visible around the perimeter.

Warning: Do not place the carburetor cover on the table with the float down!

Cleaning the float chamber

It is carried out to remove sediment that forms at its bottom. With the cover removed, you need to remove the bar with the accelerator pump piston and economizer drive and remove the spring from the guide. Next, rinse and scrape off those deposits that are easily removed. Dirt that adheres firmly to the walls does not pose a danger - let it remain. Otherwise, if you do not work carefully, debris may begin to float inside. The likelihood of clogging of channels or jets due to improper cleaning is much greater than during normal operation.

There is only one source of debris in the float chamber - gasoline. Most likely, the fuel filter on the engine does not work (that is, it formally works, but does not filter anything). Check the condition of all filters. Besides the filter fine cleaning, which is installed on the engine and has a mesh, paper or ceramic filter element inside, there is another one on the carburetor itself. It is located under plug 1 (Fig. 17) near the gasoline supply fitting on the carburetor cover.

Filter care

It consists of cleaning the sump from dirt, water and sediment and replacing the paper filter elements. Mesh filter elements should be washed, and ceramic ones can be burned out by heating them until the gasoline accumulated in the pores spontaneously ignites. Of course, this must be done in compliance with all precautions. After cooling slowly, the ceramic filter element can be reused many times.

Checking the condition of the jets

Below the float at the bottom of the float chamber are two main fuel jets. Unscrew the two plugs 10 (Fig. 17) from the outside of the float chamber housing and unscrew the fuel nozzles of the main metering system. Check the cleanliness of their channels and read the markings stamped on each of them. The markings must match the carburetor brand.

Rice. 17. View of the carburetor from the drive side:
1 — fuel filter plug; 2—opener adjustment bar;
3 — accelerator pump drive lever; 4 — air damper axis;
5 — air damper drive lever; 6 - traction; 7 — “quantity” screw;
8 — throttle drive lever; 9 — vacuum tap for the valve
recycling; 10 — plugs of the main fuel jets

On the upper plane of the housing connector, two air jets of the main dosing system 6 are visible (Fig. 18). Air jets are more likely to become clogged than fuel jets because they are subject to “direct hit” from particles flying from above along with the air. The reason may be imperfect air purification.

Traditionally, engines with K-126 were equipped with an inertia-oil air filter. The degree of air purification in them reaches 98% with proper assembly and timely maintenance (changing the oil in the filter housing, washing the filter). But if a gasket is not placed between the filter housing and the carburetor or it is squeezed to the side when tightening, then a gap is formed for untreated air through which it can penetrate into the engine.

Relatively recently, air filters with a paper filter element, the degree of purification of which approaches 99.5%, began to be installed on engines ZMZ-511, -513, -523. The filter element is located in a massive metal housing with a lid fastened with five fasteners. If the fasteners on the filter housing are weak, the filter element does not press and allows air to pass by. Loose fasteners are usually the result of backfire into the carburetor when running on a cold engine or due to incorrect adjustments. If you notice that some of the five fasteners are loose and rattling, try bending them, although this will require some effort. Fuzzy compression of the filter element inside the housing also occurs if its sealing rings on the end surfaces are made of hard rubber or plastic. When purchasing, pay attention to this and do not buy an item with a dubious sealing belt.

Rice. 18. View of the float chamber body:
1 - small diffusers; 2 — block of economizer and accelerator sprayers;
3 - large diffusers; 4 — idle fuel jets;
5 — plugs of idle air jets; 6 — main air jets;
7 — main fuel jets; 8 — economizer valve;
9 — accelerator pump discharge chamber

The second point is the condition of the engine. The fact is that it uses a closed crankcase ventilation system (Fig. 19). Crankcase gases, which are a mixture of exhaust gases that penetrated into the crankcase through the leakage of the piston rings, and oil vapor, are introduced by a special hose 3 into the air filter space for re-combustion.

Rice. 19. Scheme of a closed crankcase ventilation system:
1 — air filter; 2 - carburetor; 3 — hose of the main branch of ventilation;
4 — hose for additional ventilation branch; 5 - oil separator;
6 - gasket; 7 - flame arrester; 8 — inlet pipe; 9 - fitting

The oil captured by these gases must be separated in the oil separator 5 and if everything is in order, only traces of it are visible on the inner surface of the filter housing (with a paper filter element). However, when using very bad oil, it actively oxidizes inside the engine, forming a huge amount of carbon deposits. When passing through the internal cavities of the engine, crankcase gases take with them carbon particles from the walls and are carried into the cavity of the air filter and further to the carburetor. Particles settle on the top cover of the carburetor and penetrate the air jets, clogging them. Reducing the cross-section of the air jets when clogged shifts the composition of the prepared mixture towards enrichment. This means, first of all, excessive fuel consumption and increased emissions of toxic components.

Considering a closed ventilation system as unnecessary and harmful, drivers often remove the ventilation hose from the air filter. At the same time, such an amount of dirty air passes through the open ventilation fitting that it is no longer possible to talk about the quality of filtration, and one is also surprised at the rapid clogging of the carburetor (and engine wear).

A consequence of the operation of the crankcase ventilation system is a dark coating on all surfaces of the carburetor air tract: on the walls of the neck, diffusers, and dampers. There is no need to strive to clean it completely. The plaque sticks tightly to the walls and cannot get into the narrow calibrated channels and clog the jets.

Idle fuel jets 4 are screwed into the top of the carburetor connector plane (Fig. 18). The diameters of the channels of these jets are about 0.6 mm and the likelihood of clogging is high for them. Next to them, idle air jets are screwed into the side of the housing under the plugs. Turn them out and make sure that both the jets and the air supply channels are clean.

It is better to clean the jets by wetting them with gasoline and at the same time cleaning them with a match or copper wire. Do this several times, gradually loosening the hardened deposits. Do not use brute force - you may damage the calibrated surface. As a result, the characteristic metallic sheen of the brass surface should appear on the jets.

At the bottom of the float chamber there is an economizer valve 8 (Fig. 18). To unscrew it, you must use a screwdriver with a wide blade. The valve is non-separable and consists of a threaded body, the valve itself and a spring that keeps it closed. The economizer valve must be sealed when free. When tested on a specialized draining device under a water pressure of 1000 ± 2 mm, compressing the valve spring, no more than four drops per minute are allowed to fall. Otherwise, the valve is considered leaky and should be replaced.

Removing the float mechanism.

Remove the float shaft from the supports in the cover, now remove the float and float mechanism valve. The float in K-126 is brass, soldered from two halves, or plastic rarely fails, since the only thing that can happen to it is loss of tightness due to the fact that the float touches the walls of the float chamber. Examine the float; is there any characteristic rubbing on it, especially on the lower part?

The valve assembly on the K-126 is quite reliable thanks to a polyurethane sealing washer mounted on the valve shank. Inspect the valve and, above all, the sealing washer. It should not be hard (this means the material loses its properties and has aged), and should not become limp or “sticky.” If the washer is normal, then other possible valve deficiencies (misalignment, wear of the guide surface) will be compensated for by it. Look at the bottom of the valve body screwed into the carburetor body, where the sealing washer rests during operation. There should be no dark traces visible on the surface, which are exfoliated particles of the washer material, a sure sign that the material is not real (real SKU-6 polyurethane is light). Clean them carefully, try not to leave scratches, which in the future will cause leaks.

If you suspect that the washer has become old or worn out, replace it. Remember that the quality of the valve mechanism is completely determined by the condition of the sealing washer, and the entire operation of the carburetor largely depends on the operation of the valve mechanism.

Air damper inspection

On the lid there is an air damper with two valves, which forms the basis of the starting device. By turning the drive lever, make sure that the air damper in the closed position completely covers the carburetor neck. If there are gaps around the perimeter of the damper, then you can slightly loosen the fastening screws without unscrewing them completely, and with the drive lever pressed, try to move the damper, achieving the tightest fit to the neck. Gaps between the housing and the damper are allowed no more than 0.2 mm. After adjustment, tighten the fastening screws securely. It is not recommended to remove the air damper unless absolutely necessary. Remember that the fastening screws at the ends are riveted.
The air valves on the damper should move easily on their axes and fit tightly into place under the action of springs.

Inspection of the throttle valve drive mechanism

Turn the carburetor over and remove the four screws securing the mixing chamber housing. In the free state, throttle valves 1 (Fig. 21) must be in the open position, since they are opened by a spring in the limiter housing. Turn the throttle valve lever and make sure that the valves close smoothly without jamming. When moving the dampers, a characteristic hissing of air should be heard in the above-membrane cavity of the restrictor. This indicates the integrity of the membrane. If the dampers do not open, check the condition of spring 1 (Fig. 20). To do this, open the cover of the membrane limiter actuator. The spring may be broken or come off its pin. Tongue 3 on the double-arm lever adjusts the angle of the throttles when fully open. It should be 8° to the vertical axis.

Rice. 20. View of the actuator
limiter (cover removed):
1 — spring, 2 — double-arm lever, 3 — tongue

Above the edges of the closed throttle valves, both openings of the transition systems should be visible (or only slightly covered by the edges), one opening for the vacuum intake to the vacuum ignition timing regulator (at a height of about 0.2...0.5 mm from the edge in one chamber) and the opening vacuum selection to the recirculation valve (at a height of about 1 mm from the edge in the other chamber).

Rice. 21. Mixing chamber housing with limiter:
1 — throttle valves; 2 - air supply hole
to the membrane restrictor mechanism; 3 - membrane mechanism;
4 — limiter body; 5 - fuel supply holes
to “quality” screws and vias; 6 — “quality” screws;
7 - vacuum intake hole for the vacuum regulator
ignition timing

Incorrect position of the transition holes relative to the throttle valves disrupts the transition from the operation of the idle system to the operation of the main metering system. In addition, it indicates violations of regulations. If the throttles are open at idle at a large angle (the vias are “hidden” under the edge), then a lot of air is supplied to the engine at idle through the throttle. The reasons are very different, for example, the mixture is too lean, a cylinder (or several) does not work, the channel of the small ventilation branch 9 (Fig. 19) is clogged, through which a certain amount of air (along with crankcase gases) bypasses the carburetor.

Now turn out the “quantity” screw almost completely. The dampers will close so much that they touch the walls of the mixing chamber. In this position, it is necessary that the gaps between them and the walls are almost absent and, if possible, equal. The tightness of closing the chokes is checked against the light (you need to look through the closed chokes into the light of the lamp). If the difference is large, you can slightly loosen the fastening screws without unscrewing them completely, and with the drive lever pressed, try to move the dampers, achieving the tightest fit between them and the walls. Gaps between housings and dampers are allowed no more than 0.06 mm. Tighten the fastening screws and screw in the “quantity” screw so much that the dampers are in the position described above relative to the via holes. Remember this position of the screw, for example, by the location of the slot. This will help make adjustments to the engine when the carburetor is already in place.

In the usual case, a black layer of soot accumulates along the contact line between the throttle and the wall, filling the gap between them. This “sealing” layer is not dangerous as long as it does not cover the vias. If you have any suspicions, scrape off the carbon deposits by soaking them in gasoline and clean all channels related to the transition systems.

Checking the condition of the accelerator pump

It comes down to revising the rubber seal on the piston and installing the piston in the housing. The cuff must, firstly, seal the injection cavity and, secondly, move easily along the walls. To do this, there should be no large marks (folds) on its working edge and it should not swell in gasoline. Otherwise, friction against the walls may become so great that the piston may not move at all. When pressing the pedal, the driver acts through the rod on the bar that carries the piston. The bar moves down, compressing the spring, and the piston remains in place.

Installing the piston and checking the performance of the accelerator pump is carried out after subassembling the carburetor. Before doing this, check the condition of the accelerator inlet valve, which is located at the bottom of the discharge chamber. It is a steel ball placed in a niche and pressed with a spring wire clamp. Under this bracket, the ball can move freely by about a millimeter, but cannot fall out of its niche. If the ball does not move, the bracket must be removed, the ball removed and its niche and channels thoroughly cleaned. The gasoline supply channel (under the ball) is drilled from the side of the float chamber. The channel for discharging gasoline to the atomizer is drilled from the opposite side of the housing and plugged with a brass plug.

Rice. 22. View of the carburetor without a cover:
1 — economizer rod; 2 — economizer and accelerator drive strip;
3 — accelerator piston; 4 - main air jets;
5 — fuel supply screw of the accelerator pump;
6 — “quality*” screws; 7 — “quantity” screw

Next, unscrew the brass fuel supply screw 5 (Fig. 22) and remove the accelerator pump and economizer nozzle block. Immediately after this, turn the carburetor body over so that the accelerator discharge valve falls out (do not forget to put it in place when reassembling). There are four nozzles on the nozzle block (two economizers and two accelerators) that need to be checked for cleanliness. Their diameter is about 0.6 mm, so use thin steel wire.

Take a thin rubber hose and blow out the channels from the accelerator pump chamber 9 (Fig. 18) and from the economizer 8 to the sprayer (the economizer must be turned out). If the channels are clean, then screw in the economizer, lower the accelerator discharge cap into place and screw in the nozzle block.
Pre-assembly of the carburetor begins with mounting the mixing chamber housing onto the float chamber housing. First place the gasket on the inverted housing, observing the position of the holes. On carburetors that were barbarically screwed to the engine, as a rule, the mounting “ears” on the body are deformed. If you put a new gasket on them, it will not crimp in the middle.

The deformed plane of the housing connector must be corrected

Check whether there are large diffusers 3 in the housing (Fig. 18), which could fall out during disassembly, and whether they are of the diameter that is regulated * for this modification (in the vast majority 27 mm). The size is marked on the upper end by casting. Now place the mixing chamber housing on top and secure it with four screws.
Installation and testing of the accelerator pump and economizer. Insert a spring and a bar with an accelerator piston and an economizer rod into the float chamber body. Check the timing of turning on the economizer and the stroke of the accelerator piston (Fig. 23). To do this, press bar 1 with your finger so that the distance between it and the connector plane is 15±0.2 mm. In this case, using the adjusting nut 2 of the rod, it is necessary to establish a gap of 3 ± 0.2 mm between the end of the nut and the bar 1. After adjustment, the nut should be compressed.

This approach, given in all operating instructions, will ensure the correct moment for turning on the economizer only if rod b (Fig. 17) of the accelerator pump drive lever has a standard length (98 mm). The indicated value of 15±0.2 mm corresponds to the position of the bar with the throttle fully open. If the thrust is shorter, the economizer will turn on earlier, and the piston stroke of the accelerator pump will become less. However, you should not try to set the exact moment when the economizer is turned on. The moment of switching to rich mixtures should occur when the throttle is opened at approximately 80%. At rotation speeds up to 2500 rpm, enrichment could begin even earlier, when the throttle is opened to half. Economy does not suffer from this, but power, of course, does not increase. The position of the accelerator pump piston is not specified in the instructions. It is understood that it should rest against the bottom of the plenum chamber at the same time as the throttle is fully opened. Often the accelerator adjusting nut is tightened in the hope of increasing the flow (to get rid of “dips”). This does not change anything, since the piston stroke does not increase. It is better to monitor the condition of the elements.

Rice. 23. Checking when the economizer is turned on:
1 — drive strip; 2 — switching rod nut

Fill the float chamber with gasoline to the middle level. Since the accelerator pump drive does not work without the top cover, press the bar directly with your finger. Press hard and hold the bar for some time. At the same time, clear streams of gasoline should escape from the accelerator pump nozzles. Without the top cover, their direction, power and duration are clearly visible. Observe how the piston moves after pressing the bar. There should be no delay from the moment of pressing until the moment the piston moves away. The total flow time of the jets (piston movement) is about a second. If there is a delay, if the jets are sluggish and flow for a long time, the piston collar will have to be changed. If all of the above requirements are met, then we can assume that the accelerator pump is generally working.

If the piston moves but there is no flow through the nozzle, try working with the accelerator without the nozzle. Unscrew the sprayer, remove the discharge valve and press the accelerator bar. Be careful not to bend too low - the jet of gasoline can hit you high and hit you in the face. If no fuel comes out of the vertical channel, it means that the system of supply channels from the piston is clogged. If fuel flows here, then clean the nozzle itself. If the sprayer is clean, but there is no flow through it, check whether the discharge chamber under the piston is filled. Remove the piston and look into the chamber. It should be full of gasoline. If it is not there, check the channels for supplying gasoline from the float chamber to the ball under the piston and the mobility of the ball itself. When you press the piston from the supply channel, there should not be a breakthrough of a jet of gasoline in the opposite direction (the ball valve is leaking). Be sure to check for the presence of the discharge valve (brass needle) under the nozzle block, it is easy to lose.

Subsequently, the feed can be quantified. To do this, the carburetor assembly will need to be placed above the container and ten times in a row, holding for a few seconds after pressing and after releasing, turn the throttle drive lever to full travel. For ten full strokes, the accelerator pump must supply at least 12 cm3 of gasoline.

Setting the fuel level

Take the carburetor cover, insert a needle with a working sealing washer on it into the valve body of the float mechanism, place the float and insert its axis (Fig. 8). Holding the cap upside down as shown in the figure, measure the distance from the edge of the float to the plane of the cap. Distance A should be 40 mm. The adjustment is made by bending the tongue 4, which rests against the end of the needle 5. At the same time, make sure that the tongue always remains perpendicular to the axis of the valve, and there are no nicks or dents on it! At the same time, by bending the limiter 2, you should set the gap B between the end of the needle 5 and the tongue 4 within 1.2 ... 1.5 mm. On carburetors with a plastic float, clearance B is not adjustable.

Having thus set the position of the float, we, unfortunately, cannot guarantee complete tightness of the valve assembly. Try placing the lid vertically, with the float hanging down, and put a thin rubber hose with marked ends on the fuel supply fitting. Having such a hose is very convenient; you just need to mark the ends so that one always remains clean. Create excess pressure on the valve with your mouth and slowly turn the cap so that the float changes its position relative to it. The position at which air leakage stops should correspond to the distance between the float and the body, approximately equal to dimension A.

Now create a vacuum in the hose and evaluate the leak. If the valve is sealed, the vacuum remains unchanged for a long time. In the presence of non-densities of any kind, the rarefaction you create quickly disappears. If there is no tightness, then the sealing washer must be replaced. In some cases, the threaded fit of the valve body itself may be leaky. Try turning it up. Remember that the entire operation of the carburetor largely depends on the operation of the valve mechanism.

Carburetor assembly

First of all, put back all the jets that you unscrewed in the carburetor body. Screw them securely, but without excessive force, so as not to damage the slot and make it easier to unscrew in the future. Place the spring and bar with the accelerator piston and economizer rod. Place the gasket on the housing connector plane. The carburetor cover, pre-assembled, is installed on top and should fit easily into place and be centered. Finally tighten the seven screws securing the cover.

Try how the accelerator pump drive lever turns after assembly. It should move easily and still move the accelerator pump. If the lever does not move, it means that it was jammed in the wrong position during assembly. Remove the lid and start over.
Align the slot on the throttle drive lever with the tab on the accelerator drive rod. In a certain position they will coincide, and the rod will be inserted into the lever. Insert the upper end of the rod into the hole and secure with a cotter pin. Don't forget which of the two possible holes in the lever the rod was in before disassembly! By turning the throttle drive lever, now check whether the accelerator pump piston moves smoothly.

For convenience, you can even remove the small top cover that covers the drive lever with the roller that presses the bar. In the position of the throttle drive lever on the idle stop, there should be no gap between the roller and the bar. The slightest movement of the lever should lead to movement of the accelerator bar and piston. Let me remind you that the K-126 is extremely demanding on the operation of the accelerator pump; the ease of use of the car largely depends on the quality of its operation.

Adjusting the starter

carried out on a fully assembled carburetor. Turn the choke control lever all the way. The throttle must now be slightly open to a certain angle, which is estimated by the size of the gap between the edge of the throttle valve and the chamber wall (see Fig. 14). In the “start” position it should be approximately 1.2 mm. The gap is adjusted as follows. Having loosened the fastening of the adjusting bar 3, located on the lever 4 of the accelerator pump drive, use the lever 5 to completely close the carburetor air damper.

Next, use lever 1 to open the throttle valves slightly so that the gap between the wall of the mixing chamber and the edge of the valve is 1.2 mm. You can insert a wire with a diameter of 1.2 mm into the gap between the edge of the throttle and the mixing chamber body and release the throttle so that it is pinched in the gap. Next, move the adjusting bar 3 until it rests against the protrusion of the lever, after which it is secured. By opening and closing the air damper several times, check that the specified gap is set correctly. Considering that the starting device on the K-126 has practically no automation, keeping the throttle slightly open is fundamentally important when starting a cold engine.

Carburetor installation

After all carburetor systems have been inspected, the cavities have been washed, and the adjustment gaps have been set, the carburetor must be correctly installed on the engine. If you did not remove the gasket from the engine intake pipe during dismantling, then feel free to reinstall the carburetor. Otherwise, make sure that the gasket is laid in the same way as before. Incorrect orientation is dangerous because the imprints of the channels of the lower part of the carburetor on the gasket will move to new places, and air will be sucked into the formed recesses.

Do not try to tighten the carburetor mounting nuts too much - you will deform the pads. Insert the spherical head strut that we left on the pedal rod into the throttle drive lever and tighten the nut from the inside. Reinstall the return spring, gasoline supply hose, vacuum take-off to the vacuum ignition timing regulator and recirculation valve. Secure the rod shell and the air damper drive rod itself.

Checking control mechanisms.

Pull the choke control handle on the panel in the cabin all the way and evaluate how clearly the air damper on the carburetor closes. Now push the handle down and make sure that the air damper has opened completely (stands strictly vertically). If this does not happen, loosen the screw securing the shell and pull the shell a little further. Tighten the screw and check everything again. Remember that incorrect position of the choke when the drive button is recessed leads to increased fuel consumption.

When the throttle valves are fully opened, the gas pedal in the cabin must rest against the floor mat. This prevents the occurrence of excessive stress in drive parts and increases their durability. Ask your partner to press the pedal to the floor in the cabin, and yourself evaluate the degree of throttle opening on the carburetor. If the throttle can be turned by hand to any other angle, you should shorten the length of the drive rod by screwing the tip deeper.

After the final adjustment, the pedal should be pressed to the floor when the throttle is fully open, and there should be some free play in the rods when the pedal is released.

Fuel level monitoring

should be carried out after final installation of the carburetor on the engine. Older carburetors had a sight glass through which the level could be seen. In the latest modifications there is no window, but only mark 3 (Fig. 9) on the outside of the case. To control, it is necessary to screw in a fitting with the appropriate thread instead of one of the plugs 2, which blocks access to the main fuel jets, and put a piece of transparent tube on it (Fig. 24). The free end of the tube should be raised above the parting line of the housings. Using the manual lever, fill the fuel pump and fill the float chamber with gasoline.

According to the law of communicating vessels, the level of gasoline in the tube and in the float chamber itself will be the same. By placing the tube against the wall of the float chamber, you can assess whether the level matches the mark on the body. After taking the measurement, drain the fuel from the float chamber through a tube into a small container, preventing it from getting on the engine, unscrew the fitting and screw the plug back into place. Simultaneously with checking the level, the absence of leaks through gaskets, plugs and plugs is checked.

Fuel level mark

Rice. 24. Scheme for checking the fuel level in the float chamber:
1 - fitting; 2 — rubber tube; 3 - glass tube

If the fuel level does not coincide with the mark by more than 2 mm, you will have to remove the cover and repeat setting the level of the float chamber by bending the tongue.

Pre-setting idle speed. Starting the engine after installing the carburetor may take longer than usual because the float chamber is empty and the fuel pump will need time to fill it. Close the choke completely and start the engine with the starter. If the fuel supply system (primarily the fuel pump) is working properly, then the start will occur in 2...3 seconds. If after even twice as long there are no flashes, then there is reason to think about the availability of gasoline or the serviceability of the fuel supply system.

Warm up the engine by gradually pushing down the choke control handle and not allowing it to develop too much. high speed. If you managed to completely remove the drive handle and the engine is idling on its own (even if not very stable), proceed to the final idle adjustment.

If the engine refuses to work when the gas pedal is released (or is very unstable), begin a rough adjustment of the idle speed system. To do this, hold the throttle with your hand so that the engine runs as slowly as you can hold it (the rotation speed is about 900 rpm"1). Do not touch the "quantity" screw. When inspecting the throttle valves, it had to be installed in the “correct” position in relation to the vias. As a last resort, you can temporarily move the screw, remembering how much you turned it.

Try adding fuel by unscrewing the “quality” screws. If the engine runs more steadily, then you are on the right track. If the speed begins to drop, you should move towards leaning (decreasing the flow). If, despite all the manipulations with the “quality” screws, the engine does not start to work more stable, the reason may be that the float chamber valve is not tight. The fuel level rises uncontrollably, becomes higher than the edge of the nozzle, and gasoline begins to spontaneously flow into the diffusers. The mixture becomes richer and may even go beyond the flammable limits.

The opposite situation is that the channels in the idle system are clogged and fuel does not flow at all. The smallest cross-section is in the idle fuel jet. This is where the likelihood of clogging is highest. While holding the throttle with your hand, try to unscrew one of the idle fuel jets 9 by half a turn with your other hand (Fig. 22). When the idle jet moves away from the wall, a huge (by its standards) gap is formed, into which the high vacuum present in the channels sucks out gasoline along with debris. In this case, the mixture becomes over-enriched, and the engine will begin to “lose” speed.

Perform this operation several times, then tighten the nozzle completely. Repeat the operation with another jet. If the engine can idle on its own with the jet slightly unscrewed, but when screwing it back in place the engine stalls, either the jet itself is clogged (solidly) or the idle channel system is clogged.
Alternatively, it is possible that it is not the carburetor that is to blame for the unstable operation, but the EGR exhaust gas recirculation system valve. It is installed on engines relatively recently (Fig. 25).

Srog serves to reduce emissions of nitrogen oxides from exhaust gases by supplying part of the exhaust gases from manifold 1 to the intake tract through a special spacer 4 under the carburetor 5. The operation of the recirculation valve is controlled by vacuum from the throttle body, taken through a special fitting 9 (Fig. 17) .

In idle mode, the EGR system does not work, since the vacuum intake hole is located above the throttle edge. But if the recirculation valve does not completely close the channel, then exhaust gases can penetrate into the intake pipe and lead to a significant dilution of the fresh mixture.

Adjusting the idle system

After eliminating the defects, you can make final adjustments to the idle system. The adjustment is made using a gas analyzer according to the GOST 17.2.2.03-87 method (as amended in 2000). The content of CO and CH is determined at two crankshaft rotation frequencies: minimum (Nmin) and increased (Nrev.), equal to 0.8 Nnom.” For eight-cylinder ZMZ engines, the minimum crankshaft rotation is set to Nmin= 600±25 min-1 and Npov= 2000+100 min"1.

Rice. 25. Exhaust gas recirculation scheme:
I - recirculated gases; II - control vacuum;
1 - intake manifold; 2 — recirculator tube;
3 — hose from the thermal vacuum switch to the carburetor;
4 — recirculation spacer; 5 carburetor;
6 — hose from the thermal vacuum switch to the recirculation valve;
7 - thermal vacuum switch; 8 recirculation valve;
9 — recirculation valve stem

For vehicles produced after 01/01/1999, the manufacturer must indicate the maximum permissible carbon monoxide content at the minimum rotation speed in the technical documentation for the vehicle. Otherwise, the content of harmful substances in the exhaust gases should not exceed the values given in the table:

For measurements, it is necessary to use a continuous infrared gas analyzer, having previously prepared it for operation. The engine must be warmed up not lower than the operating temperature of the coolant specified in the vehicle's operating manual.

Measurements should be carried out in the following sequence:

set the gear shift lever to neutral position;
apply the parking brake to the car;
turn off the engine (while it is running), open the hood and connect the tachometer;
install the gas analyzer sampling probe into the vehicle exhaust pipe to a depth of at least 300 mm from the cut;
fully open the carburetor air damper;
start the engine, increase the rotation speed to Npov and operate in this mode for at least 15 seconds;
set the minimum engine speed and, no earlier than 20 s later, measure the content of carbon monoxide and hydrocarbons;
set an increased engine speed and, no earlier than 30 s later, measure the content of carbon monoxide and hydrocarbons.
If the measured values deviate from the standards, adjust the idle air system. At the minimum rotation speed, it is enough to influence the screws with “quantity” and “quality”. Regulation is carried out by successively approaching the “target”, adjusting one and the other screw in turn until the required values of CO and CH are achieved at a given frequency Nmin. You should always start with “quality”, so as not to interfere with the adjustment of the position of the chokes relative to the vias. If, after adjusting the mixture composition using the “quality” screws alone, the engine speed goes beyond 575...625 min”1, use the “quantity” screw.

Since the K-126 has two independent idle systems, adjusting the mixture composition has its own characteristics. When changing the mixture composition with the “quality” screw, the rotation speed can simultaneously change. By rotating one of the “quality” screws, find its position at which the rotation speed will be maximum. Leave it and do the same with the second screw. The readings of the gas analyzer for CO will probably be about 4%. Now we turn both screws synchronously (at the same angles) until the required CO content is obtained.

The hydrocarbon content is determined more by the general condition of the engine than by carburetor adjustments. A serviceable engine can easily be adjusted to CO values of about 1.5% at CH values of approximately 300...550 ppm. It makes no sense to chase smaller values, since the stability of the engine significantly decreases while the consumption increases (contrary to popular belief). If hydrocarbon emissions exceed the given average values by several times, the reason must be sought in increased oil breakthrough into the combustion chamber. It may be worn out valve stem seals, broken bushings valves, incorrect adjustment of thermal clearances in valves.

The GOST limit values of 3000 million"1 are achieved on worn-out, misaligned, oil-consuming engines, or in cases where one or more cylinders are not working. A sign of the latter can be very small amounts of CO emissions.

In the absence of a gas analyzer, you can achieve almost the same accuracy of regulation using only a tachometer or even by ear. To do this, on a warm engine and with the position of the “quantity” screw unchanged, find, as described above, the position of the “quality” screws that ensures the maximum engine speed. Now use the “quantity” screw to set the rotation speed to approximately 650 min.”1. Check with the “quality” screws whether this frequency is the maximum for the new position of the “quantity” screw. If not, repeat the entire cycle again to achieve the required ratio: the quality of the mixture ensures the highest possible speed, and the number of revolutions is approximately 650 min."1. Remember that the “quality” screws must be rotated synchronously.

After this, without touching the “quantity” screw, tighten the “quality” screws enough so that the rotation speed decreases by 50 min”1, i.e. up to the regulated value. In most cases, this adjustment meets all GOST requirements. Adjustment in this way is convenient in that it does not require special equipment, and can be carried out every time the need arises, including for diagnosing the current state of the power system.

In case of non-compliance of CO and CH emissions with GOST standards at an increased rotation speed (Npov” = 2000 * 100 min “‘), influencing the main adjusting screws will no longer help. It is necessary to check whether the air jets of the main metering system are dirty, whether the main fuel jets are enlarged and whether the fuel level in the float chamber is excessive.

Checking the pneumatic centrifugal speed limiter is quite complicated and requires the use of special equipment. The tightness of the valve in the centrifugal sensor, the correct adjustment of the sensor spring, the tightness of the membrane, and the actuator jets must be checked. However, you can check the operation of the limiter directly on the car. To do this, on a well-warmed and adjusted engine, open the throttle valves completely and measure the crankshaft rotation speed with a tachometer.
The limiter works correctly if the rotation speed is within 3300+35° min"1.

If you decide to carry out such a check, be prepared to “reset” the throttle in case of unexpected engine acceleration. If everything is in order, then acceleration to such a frequency does not pose any danger to the engine. Many drivers disable the limiter themselves to get additional power at higher revs. Sometimes, when the limiter is activated, for example when overtaking, it can actually cause an unwanted delay due to the need to change gears.

But even the shutdown should be done correctly. The universally accepted disconnection of tubes from the centrifugal sensor leads to a constant flow of dirty air from the street under the throttle valves. If the tubes are plugged after disconnection, the membrane actuator will work (close the throttle).

When disabling the limiter correctly, the chamber should be closed, bypassing the centrifugal sensor. To do this, one of the tubes from the membrane chamber (for example, from outlet 1 in Fig. 9) should be screwed into the second outlet 7 of the same chamber

Possible malfunctions of the fuel supply system and methods for eliminating them

Sometimes, even if maintenance intervals are observed, situations may arise when the carburetor fails. When troubleshooting, first of all, it is necessary to identify the system or component that may be causing the existing defect. Very often, the carburetor is attributed to engine malfunctions, the real cause of which is, for example, the ignition system. She generally acts as a “culprit” more often than is commonly believed.
To eliminate the influence of one system on another, it is necessary to clearly understand that carburetor system power supply is inertial, i.e. changes in its operation can be traced in several successive engine operating cycles (their number can be measured in hundreds). It is not able to make any changes to the operation of one working cycle (this is at most 0.1 seconds). The ignition system, on the contrary, is responsible for each individual cycle in the engine. If there are omissions of individual cycles, manifested in the form of short jerks, then this is most likely the reason.

Of course, the division of powers between systems is not so clear. The fuel supply system is not able to “turn off” one cycle, but can create conditions for unfavorable operation of the ignition system, for example, an excessively lean mixture. In addition, the fuel supply system contains a number of subsystems, each of which can make its own characteristic “contribution” to the operation of the engine.

In any case, before you start looking for defects in the carburetor, or even adjusting it, you need to make sure that the ignition system is working properly. The main argument in defense of the ignition system - “there is a spark” - cannot serve as proof of serviceability.

It is very difficult to verify the energy parameters of the ignition system. A spark can be supplied at the right moment, but carry with it several times less energy than is necessary for reliable ignition of the mixture. This energy is enough to operate the engine in a narrow range of mixture compositions, and is clearly not enough to guarantee ignition in cases of the slightest deviation (depletion associated with acceleration, or enrichment during cold start-up and warm-up).

For the ignition system, only the setting advance angle (spark position relative to TDC) is adjusted at the minimum idle speed. Its value for engines ZMZ 511, -513... is 4° of crankshaft rotation after (!) TDC. At other frequencies and loads, the ignition timing is determined by the operation of the centrifugal and vacuum regulators located in the distributor. Their influence on performance characteristics (primarily fuel consumption and power) is enormous. How the regulators work, how accurately they set the advance angles in each mode can only be checked on special stands. Sometimes the only way to identify faults is to sequentially replace all elements of the ignition system.

Before examining the carburetor, you must also ensure that the rest of the fuel supply system is working properly. This is the fuel supply line from the gas tank to the gas pump (including the fuel intake in the tank), the gas pump itself and fine fuel filters. Clogging of any of the path elements leads to a restriction of fuel supply to the engine.

Supply limitation means the impossibility of creating fuel consumption greater than a certain value. Engine power is inextricably linked with fuel consumption, which will also have a certain limit. Consequently, if the fuel supply is disrupted, your car will not be able to move at maximum speeds or uphill, but this will not prevent it from idling properly or when driving evenly at low speeds.

Another sign of fuel supply limitation is that the defect does not appear instantly. If you idled for at least a minute and immediately drove with a heavy load, then the supply of gasoline in the carburetor float chamber will ensure normal movement for some time. The engine will begin to feel fuel starvation caused by limited supply as the reserve is exhausted (at a speed of 60 km/h, you can drive about 200 meters with the amount of gasoline that is in the float chamber).

To check the fuel supply, disconnect the supply hose from the carburetor and direct it into an empty 1.5...2 liter bottle. Start the engine with the remaining gasoline in the float chamber and watch how the gasoline flows. If the system is working properly, the fuel comes out in a powerful pulsating jet with a cross-section equal to the cross-section of the hose. If the stream is weak, try repeating everything by disconnecting the fine fuel filter. Naturally, if there is an effect, the filter is to blame and needs to be replaced.

You can check the section of the line up to the fuel pump only by blowing it in the “reverse direction.” You can even do this with your mouth, remembering to open the cap on the gas tank. The line should be purged relatively easily, and in the tank itself you should hear a characteristic gurgle of air passing through the gasoline.
After checking the lines before and after the fuel pump and not achieving any effect, check the fuel pump itself. A small mesh is installed in front of its intake valves. If contamination is excluded, check the tightness of the pump valves or the functionality of its drive from the engine camshaft.

After making sure that the ignition system is working and the supply part of the power system is in good condition, you can begin to identify possible carburetor defects. This section is independent and troubleshooting work can be carried out without prior maintenance and carburetor adjustment. Most often, such work has to be performed in case of malfunctions that do not generally affect operation, but cause certain inconvenience. These can be various kinds of “failures” when opening the throttle, unstable work idling, increased fuel consumption, sluggish vehicle acceleration. Much less common are situations when the engine, for example, does not start at all. In such cases, as a rule, it is much easier to find and fix the problem. Remember one thing: all carburetor malfunctions can be reduced to two - either it prepares a mixture that is too rich or too lean!

The engine does not start

There can be two reasons for this: either the mixture is over-rich and goes beyond the ignition limits, or there is no fuel supply and the mixture is over-lean. Over-enrichment can be achieved both due to incorrect adjustments (which is typical for a cold start) and due to a violation of the carburetor seal when the engine is stopped. Over-leaning is a consequence of incorrect adjustments (during a cold start) or lack of fuel supply (clogging).

If no flash occurs when the starter is cranked, there is most likely no fuel supply at all. This is true for cold and hot starts. On a hot engine, for greater reliability, close the air damper a little and repeat the start again. The same reason may be to blame if, when cranked by the starter, the engine made several flashes or even worked for a few moments, but then went silent. There was simply enough gasoline only for a short time, for a few cycles.

Make sure the fuel supply line is in good condition. Remove the air filter cover and, opening the throttle valves by hand, see if a stream of gasoline comes from the accelerator pump nozzles. The next step will probably be to remove the top cap of the carburetor and see if there is gasoline in the float chamber (unless, of course, there is an inspection window on the carburetor).

If there is gasoline in the float chamber, then the reason for difficulty starting a cold engine may be that the air damper is not tightly closed. This may be due to misalignment of the damper on the axis, tight rotation of the axis in the housing or all parts of the starting device, or incorrect adjustment of the starting mechanism. A mixture that is too lean during a cold start is unable to ignite, but at the same time it carries with it enough gasoline to “flood” the spark plugs and stop the starting process due to the lack of a spark.

A hot engine with gasoline in the float chamber must start, at least with the air damper closed, unless the main fuel jet is completely clogged. On a hot engine, the opposite situation is more likely when the engine does not start due to over-enrichment. The fuel pressure after the fuel pump remains for a long time in front of the float chamber valve, loading it. A worn valve cannot cope with the load and leaks fuel. Having evaporated from the heated parts, gasoline creates a very rich mixture that fills the entire intake tract. When starting, you have to crank the engine with the starter for a long time to pump through all the gasoline vapors until a normal mixture is formed. It is advisable to keep the throttle valves open.

When starting a cold engine, we artificially create a rich mixture, and over-enrichment associated with valve leakage will not be noticeable against the general background of a rich mixture. During a cold start, it is more likely that the trigger mechanism is adjusted incorrectly, for example, the throttle is opened slightly by the opener rod.

Unstable operation at idle.

In the simplest case, the reason lies in incorrect adjustment of the idle systems. Typically the mixture is too lean. Enrich it with “quality” screws; if necessary, adjust the rotation speed with the “quantity” screw.
If no visible effect is observed during adjustment, the reason may be a leak in the float chamber valve. Leakage of gasoline leads to unregulated over-enrichment of the mixture. On carburetors with a sight glass, the fuel level is higher than the glass.

Try turning the idle fuel jets tighter. If they do not touch the body with a sealing belt, the resulting gap acts as a parallel jet, significantly enriching the mixture. It is possible that the jets are set to a higher capacity than expected.
It happens that unstable operation is caused by an insufficient supply of gasoline due to a clogged idle system. The highest probability of clogging is in the idle fuel jet, where the cross-section is smallest. Try cleaning it using the method described in the “pre-setting idle speed” section.

Inability to adjust engine idle.

When adjusting the engine, a situation may arise when, despite its overall performance, it does not lend itself to toxicity adjustments. This manifests itself in increased emissions of CO and CH, which cannot be eliminated with adjusting screws.
The reason for a very rich mixture and increased CO emissions, as a rule, is the leakage of the float chamber (to a small extent, otherwise the engine simply refuses to operate in this mode), clogging of the idle air jets 8 (Fig. 22) with solid particles or resins, increased cross-section main fuel jets 7 (Fig. 18) or idle fuel jets 4.

If the level of CH hydrocarbons is high, the cause should be sought in an over-lean mixture associated with incorrect adjustments, contamination, or in the shutdown of one of the cylinders. It should be remembered that toxicity adjustments are largely determined by the condition of the engine as a whole. Check and adjust thermal clearances in the engine valve mechanism. Do not attempt to make them smaller than specified in the engine manual. Assess the condition high voltage wires, ignition coils, spark plugs.

Remember that candles age irreversibly.

Failure when opening the throttle smoothly. If the engine idles stably, obeys the “quality” and “quantity” screws, but does not accelerate when the throttle is opened smoothly or behaves very unstable, the condition of the transition systems should be checked. For a complete check, it is necessary to remove the carburetor and evaluate the condition of the vias. The latter may be clogged with carbon deposits or located too low relative to the throttle edge. In the latter case, traces of gasoline are visible on the walls of the mixing chambers, which flows from the transition holes at idle (which should not be the case). At the same time, their contribution to the increase in fuel consumption as the throttle opens becomes small, which leads to the mixture becoming leaner during the transition (until the main metering system is turned on).

Try to install the throttle valve as low as possible so that when it is closed, the vias are not visible from below. By closing the throttle, we limit the air supply (we reduce the speed) and therefore at the same time it is necessary to compensate for the air flow through the throttles either by flow through other sections or by greater operating efficiency.
Check the cleanliness of the small ventilation branch channel 9 (Fig. 19), make sure that all cylinders are working and the ignition is not set too late.

When the throttle is opened smoothly, a malfunction of the transition system will manifest itself until a certain moment, where the main metering system comes into operation. If, with such an opening, the engine performance does not improve even at high speeds, if the car jerks when driving at partial loads at a constant speed, if the behavior becomes much better when the throttles are fully opened (sometimes the engine does not work at all if the throttle is not fully open), then you should check the condition of the main fuel jets. Unscrew the plugs 2 (Fig. 9) in the carburetor body, and remove the fuel jets 7 (Fig. 18). See if there are any particles on them. As a rule, there is a small grain of sand that covers the passage section.

If the nozzle is clean and the car behaves according to the described patterns, it can be assumed that the entire fuel tract of the main metering system is contaminated (emulsion well, outlet channel to the atomizer, incorrect placement of small diffusers) or the nozzle markings do not correspond to the required ones. The latter most often occurs when replacing standard factory jets with new ones from repair kits. Do not try to enrich the mixture with “quality” screws; in this situation this will not help, since they only affect the adjustment of the idle air systems.

A dip when opening the throttle sharply, which disappears after the engine has been running for 2...S seconds, may indicate defects in the accelerator pump. The accelerator pump on the K-126 is an element of fundamental importance and the entire operation of the carburetor largely depends on how it works. Even with a smooth opening of the throttles, a mode in which other carburetors do not need an accelerator, injection lag associated with backlash in the drive or piston friction can lead to engine stalling. Check again all the points specified in the section “checking the condition of the accelerator pump”. If elements were replaced, remember the possible quality of the rubber cuff on the accelerator piston. There is no need to strive to increase the accelerator piston stroke, since this will only increase the injection duration, and the need for additional fuel manifests itself from the very first moments of opening the throttle. It is important that a sufficient amount of gasoline is supplied during this period.

Increased fuel consumption.

The cherished desire of any driver is to reduce fuel consumption of a car. Most often they try to achieve this by influencing the carburetor, forgetting that fuel consumption is a value determined by a whole complex of devices.

Fuel is consumed to overcome various resistances the movement of the car, and the amount of consumption depends on how large these resistances are. Don't expect great results fuel efficiency a car whose brake pads or the wheel bearings are overtightened. A huge amount of energy is spent on cranking transmission and engine elements in winter, especially when using thick viscous oils. A big consumer of energy is speed. Here, in addition to friction losses of mechanisms, aerodynamic losses are added. And a very large item of energy consumption is the dynamics of the car. To travel at a constant speed of 60 km/h, a PAZ bus needs approximately 20 kW of engine power, while to accelerate from 40 km/h to 80 km/h we use an average of about 50 kW. Each stop “eats up” this energy, and for the next acceleration we are forced to spend more.

The operating process of each engine, the degree of conversion of fuel energy into work, has its own limitations. For each modification, mixture compositions and ignition timing angles are determined, giving the required output parameters in each mode. The requirements for each mode may be different. For some it is efficiency, for others it is power, for others it is toxicity.

The carburetor acts as a link in a single complex that implements known dependencies. You cannot hope to reduce fuel consumption by reducing the flow area of the jets. The reduction in the amount of fuel passing through will not be consistent with the amount of air. Sometimes it is more expedient to increase the flow area of the fuel jets in order to eliminate the leanness inherent in all modern carburetors. This will be especially pronounced when operating the car in winter, when low temperatures ambient air. All carburetor adjustments are selected for the case of a fully warmed-up engine. Some enrichment can bring the mixture closer to optimum in cases where your engine temperature is below operating temperature (for example, in winter on relatively short trips). In any case, it is necessary to strive to increase the coolant temperature. It is unacceptable to operate the engine without a thermostat; in winter conditions, measures should be taken to thermally insulate the engine compartment.

Carry out the entire set of carburetor adjustments yourself. Pay attention to:
correspondence of jets to carburetor brand;
correct adjustment of the starting device, complete opening of the air damper;
no leakage of the float chamber valve;
adjusting the idle system. Do not try to make the mixture leaner, this will not reduce consumption, but will increase the problems of transition to load modes;
monitor the condition of the engine itself. Particles or grains of sand flying from the ventilation system with a leaky air filter can clog the air jets, incorrect adjustment of the clearances in the valve mechanism will lead to unstable idling, small ignition timing will directly cause increased consumption;
Make sure there is no direct leakage of fuel from the fuel line, especially in the area after the fuel pump.
Considering the complexity and diversity of operational factors, it is impossible to give uniform recommendations for reducing operating costs. Methods that are acceptable for one driver may not be suitable for another simply due to differences in driving style or choice of driving modes. It would probably be advisable to completely trust the factory settings and sizes of the dosing elements. It is unlikely that by changing the cross-section of any jets, it will be possible to significantly change the efficiency of the engine. Perhaps this will only work out at the expense of some other parameters - power, dynamism. Remember that those who created the carburetor and selected jets for it stood within the strict framework of the need to comply with many diverse and contradictory conditions. Don't think you can get past them. Often, useless searches for new global solutions lead away from simple, basic car maintenance techniques that allow you to achieve quite acceptable but real efficiency. Isn’t it better to direct efforts in this direction, since miracles, unfortunately, do not happen.

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Float chamber

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CARBURETTORS K-126, K-135CARS GAZ PAZ

From the author

PRINCIPLE OF OPERATION AND DEVICE OF THE CARBURETOR

1. Operating modes, ideal carburetor characteristics.

2. Carburation, formation of toxic components

3. Main carburetor metering system

Be careful about the channel orientation!

4. Idle system

5. Transition systems

6. Economizer

7. Acceleration pump

8. Starting device

9. Engine speed limiter

MAINTENANCE AND ADJUSTMENT OF THE CARBURETOR

Removing the carburetor

Carburetor flushing

Removing the top cover

Cleaning the float chamber

Filter care

Checking the condition of the jets

Removing the float mechanism.

Air damper inspection

Inspection of the throttle valve drive mechanism

Checking the condition of the accelerator pump

The deformed plane of the housing connector must be corrected

Setting the fuel level

Carburetor assembly

Adjusting the starter

Carburetor installation

Checking control mechanisms.

Fuel level monitoring

Fuel level mark

Adjusting the idle system

Speed limiter

Speed limiter

Speed limiter

Speed limiter