Fuel system check valve: causes of faults and their elimination
The pump is one of the main elements of the motor. Currently, mechanical pumps are no longer used, they are replaced by more modern electronic options. Mechanical structures can only be found on vehicles released more than 15 years ago.
Fuel pumps have high performance and provide a continuous supply of gasoline, regardless of the load. However, their operation at idle is impossible without such an important element as the check valve of the fuel system. It prevents the formation of excessive pressure in the system and, as a consequence, the breakage of the fuel hoses.
The purpose of the vacuum valve is to transfer excess gas into the fuel tank through a special hose. He also has the name of the fuel pressure regulator and is a structure consisting of a spring, a membrane and the valve itself.The housing has three outlets: one for the intake manifold, the rest for removing petrol.
The opening of the valve occurs due to the displacement of the spring, which occurs as a result of vacuum when the engine speed increases. At this time, excess fuel is discharged to the gas tank. In addition to the standard location on the fuel rail, the valve may be located on the return hose itself.
Because of what there are breakdowns
Often the check valve of the fuel system VAZ fails. The reason for this may be the use of defective or substandard parts. Therefore, you should be careful when buying spare items in unchecked stores. There is also a marriage in the factory details of domestic budget cars.
Most often, damage occurs due to normal wear and tear during prolonged use. Mostly the spring and the membrane come into disrepair, cases of complete valve failure are extremely rare.
Low quality fuel can also cause damage. After filling with gasoline mixed with water, moisture is in the regulator. It can also get dirt due to the untimely replacement of the fuel filter.
Where is the fuel check valve
The location of the regulator depends on the design of the system. It can be located between the fuel injectors and the tank, on the ramp or mounted in the design of the fuel pump. Fuel type also influences where the fuel check valve will be located. The diesel engine has a distinctive design, and in it the regulator is placed next to the injection pump and low pressure pump to ensure a stable pressure at the inlet to the pump. In addition, it can be installed in front of the heating system, this option is common in vehicles with pre-heating of the fuel.
Injection domestic cars have the same valve arrangement as diesel vehicles. At the same time, not all cars are equipped with a similar detail; in some carburetor models of the old release, its function is performed by a fuel pump. It has an airtight exhaust system and is mounted on the cylinder block. At decrease in tightness start of the motor can be made only after manual pumping because all gasoline appears in a tank.
What you need to pay attention
There are characteristic signs of a check valve malfunction:
- unstable operation of the motor at minimum speed;
- the engine starts only after a long rotation of the starter and simultaneously pressing the gas pedal;
- gasoline leakage from fuel hoses, which does not pass after replacing them and tightening the clamps;
- a sharp change in idle speed.
Due to the fact that the check valve of the fuel system has a mechanical design, it is impossible to test its performance with the help of special devices used for electronic sensors. However, he does not understand and cannot be repaired due to the lack of individual parts for sale and the low cost of the structure itself.
The pressure level in the fuel system allows you to determine the health of the valve. You can measure it with a pressure gauge, connected to the department that provides power to the motor. After it remains only to fix the readings of the device. For passenger cars, the normal pressure level should be about 3 kg / cm2. In this case there should not be a sharp decrease in the level when the motor is stopped. A rapid decrease in pressure indicates that there is a malfunction in the fuel system check valve.
Other diagnostic methods
You can also check the fuel check valve of the fuel system by monitoring the pressure level when clamping the return hose, in which case it should increase. Unfortunately, this method is not suitable for all cars, as many of them have short hoses or are completely replaced with metal ones.
If the motor is not gaining momentum and starts troit, you can check without a pressure gauge. To do this, you must also pinch the return hose and observe the engine. If at this moment the required power is gained and all cylinders are functioning, it is necessary to replace the fuel check valve.
Despite the seeming simplicity, the fuel system of the car is a complex mechanism, and work with it should be made only with special skills. With at least minimal experience and knowledge of all the design features, you can independently deal with most of the problems.