Carburetor owners often face problems such as carburetor overflows. The phenomenon happens not only on models from AvtoVAZ, but also on carburetor foreign cars. Overflow is a significant re-enrichment of the mixture of fuel and air that enters the combustion chamber. The mixture is re-enriched for one reason or another associated with the carburetor. Sometimes, even with the naked eye, one can observe how gasoline pours from a diffuser atomizer in a powerful stream. There is a persistent smell under the hood. Let's look at all the reasons that lead to overflow of the carburetor, and learn how to eliminate them.
Signs
If the principles of preparing the fuel mixture in the carburetor towards enrichment are violated, then there are problems with starting the engine. A hot motor starts especially poorly. If the engine still starts, then the speed is unstable (often increased in idle mode). It is impossible to adjust or somehow stabilize the speed with the usual methods.
If the fuel mixture is too rich, then black smoke will come from the exhaust pipe - the mixture will burn out directly in the exhaust pipe. When you press the accelerator pedal, failures are possible - the rich mixture burns very badly. There will be a thick layer of black soot on the candles.
Flammable Dosage Basics
The situation when the VAZ carburetor overflows happens especially often. Before analyzing the reasons, you need to know a little about the principles of preparing the fuel mixture.
A mixture is considered normal when 14.7 parts of air falls on one part of the fuel. All other ratios are the result of an incorrectly tuned carburetor. If the ratio is from 7 to 1 to 12 to 1, then we can talk about overflow. In this case, difficulties arise in starting the engine. It must be remembered that too rich a mixture, as well as too poor, can be dangerous for the motor. It burns more slowly, which means there is a risk of valve burnout. But the combustion temperature is low.
Causes
If a carburetor overflows fuel, then this can happen for a variety of reasons. We will analyze them all. But the first thing you should pay attention to is how the float chamber is configured and how it works - gas is pumped into it, and from there through the nozzles the mixture enters the combustion chambers due to vacuum.
Needle valve leaks
In some cases, the valve freezes at its seat. To eliminate such a malfunction, sometimes a light tapping with a hammer on the carburetor cover is enough. Experts also recommend paying attention to the tightness of the valve body. Under it, on most carburetor models there is a sealing ring - you need to make sure that it is there.
To check the needle valve, it is necessary to create a vacuum by blowing it with a mouth or a rubber bulb through a hose worn on the fuel supply fitting. Defective valve does not withstand vacuum. If it is faulty, it should be replaced by a new, serviceable one. Spare parts for carburetors are better to choose wisely - recently in stores a lot of defective products.
Float leakage
Floats are needed to adjust and maintain the fuel level in the carburetor's float chamber. This is an element made of plastic or metal, hollow inside. If the float is defective or damaged, then, instead of floating up, it will sink in gasoline. The float is connected to a needle valve. Floating, the part closes the valve, blocking the flow of gasoline into the chamber. If the float sinks, the needle element is constantly open. Fuel is supplied to the chamber without any restrictions. As a result, a carburetor overflow occurs.
Floating chamber walls
This is another popular reason. Nail Poroshin in his many videos on tuning carburetors always shows how to do it. Not everyone watches these videos and when adjusting the floats do not pay attention to their position relative to the walls in the camera. In case of inept tuning, the float will touch the walls of the chamber, and eventually - overflow.
Check the position of the floats as follows. It is necessary to unscrew the screws on the cover, remove the cover. Then they look at how the floats are located. A gasket is installed on the lid, and wall prints are visible on it. The floats must be installed so that there is a distance between them and the chamber wall. This is visible on the print. It is also worth checking if the float moves easily on the axis.
High fuel level
If the carburetor overflows, the cause may be an overestimated level of fuel. When engineers created these carburetors, they calculated that the fuel level in the chamber would be strictly defined. But in fact, the level is adjusted in different ways. There are templates for adjusting the fuel level for Solex, DAAZ, but few use them. If the level is too high, the mixture will be enriched.
To check the fuel level, it is necessary to remove the carburetor cover. But before that you need to pump gas into the chamber. On Ozone-2105, 2107 models, the correct fuel level is in the middle of an inclined plane on the front wall. At Solex, for front-wheel-drive VAZs, the normal level is 29 millimeters to the bottom of the camera.
If as a result of the check the level does not correspond, then it is necessary to adjust it. This can be done by bending the floats.
Other elements of the power system
The above situations happen quite often. But carb overflow is also observed for other reasons. The other elements in the power system of the car engine are to blame. Let's analyze them in detail.
Fuel pump
If the fuel pump works with increased productivity, then more fuel is supplied to the carburetor's float chamber than necessary - it is forced by pressure. This problem is especially relevant for cars whose carburetors are not equipped with a so-called return line for dumping excess fuel. This is true for electrical and mechanical units.
In a mechanical gasoline pump, check valves, diaphragm and return spring. Faulty elements are replaced with new ones - repair kits are on sale.
Carburetor return
This is relevant only for some Solex and DAAZ models designed for installation on front-wheel drive VAZs. If the fuel drain line is faulty, deformed, clogged, there will be overflow. It is also recommended that you check the return check valve.
The problem is that the carburetor pours gasoline due to the difficulty of dumping excess fuel into the tank. He has nowhere to go, and gasoline gets first into the float chamber, and then into the cylinders. To eliminate the malfunction, carefully examine the entire line visually. You also need to blow it along with a check valve.
Sealant on the channel XX
This is also true for Solex. Gasoline with such a malfunction will leak from under the gasket. The carburetor will be all in drips. For diagnostics, remove the cover and check the rubber ring on the idle fuel channel.
If there is no ring, you need to purchase and install it. This will not only solve the overflow problem. The presence of a ring is an even and stable idle.
Economizer malfunction
This is again true for the Solex, which stands on the front-wheel drive VAZs. If the economizer diaphragm is damaged, then the fuel is not restrained by anything and will flow directly into the second carburetor chamber in a direct flow. If the ball sticks in the economizer, then the situation will be similar.
To know exactly why the carburetor overfills gasoline, you need to check the economizer.
GDS first chamber air jet
The mixture of fuel and air can be re-enriched with fuel due to a decrease in the volume of air entering the car carburetor. What is the problem? This may be due to the fact that a large fuel jet or a too small air nozzle is installed. Sometimes, when revising carburetors, the jets of the first and second chambers are confused. This is the reason that the carburetor overflows.
What to do in such a situation? Everything is very simple. Here's how to fix the carb overflow in this case. Remove the carburetor cover, take out the nozzle and clean it. If there is an aerosol can with cleaning fluid, then you can not get the nozzle. As a result, the operation of the power unit will be stable and smooth, not only at idle.
Incorrect shutter position
Due to an incorrectly configured drive, the throttle of the first carburetor chamber may be ajar. The same is true for the second camera. The higher the gap, the greater the vacuum. This causes gas to flow out of the diffuser even at idle.
If the DAAZ carburetor overflows (quite common on domestic cars), then in this case, correctly adjusting the position of the throttle valves will be enough.
Solenoid valve or plug
If the plug or EMC is not fully tightened, then the idle nozzle does not fit snugly to its seat. Excess gasoline will flow into this small gap. The correct position of the solenoid valve is when the motor stalls when the terminal is removed from it. It is better to tighten the valve or plug, and the problem should disappear.
Quality screw
Most often, the fuel mixture is enriched with a quality screw to compensate for the suction of excess air. This prevents over-depletion of the mixture. The screw is turned out more than necessary.
Check the carburetor for possible air leaks and eliminate it. You can check with a spray gun. When the engine is running, spray on the sole of the carburetor, on the connection of the cover and the bottom. If the machine starts to stall, then there is an air leak. You can also screw the quality screw back in. But then you can lose a stable idle.
Gaskets
Through cracks in the gaskets due to rarefaction, the fuel can be absorbed, greatly enriching the combustible mixture. Carefully visually check the condition of the gaskets and replace if necessary.
The gasket between the bottom of the carburetor and the manifold may also be worn out. At Ozon, experts recommend checking gaskets between the body and throttle valves.
Conclusion
That’s all the reasons. Now we know what to do. If the carburetor overflows, then you need to check this device, as well as other elements of the fuel system of the car. There is always a way out of the situation. And in most cases, this problem can be eliminated with your own hands without the help of specialists.