8.20. System of catching of fuel evaporations (EVAP) - the general information, check of a state and replacement of components
General information
The system accumulates the fuel evaporations accumulating during the parking of the car and provides a conclusion them in the inlet pipeline for burning in the course of normal functioning of the engine.
The special adsorber filled with absorbent carbon which, actually, and collects in itself(himself) fuel evaporations surely is a part of any EVAP system. The way of a conclusion of evaporations from an adsorber can vary depending on a design of concrete system. Given below will allow the reader to understand the principles of functioning of the EVAP system of any type rather in details.
|
|
The described design not necessarily has to correspond completely to a design of the system installed on the concrete car, however the principle of functioning is the general for all models equipped with system of injection of fuel. In case of identification of any deviations, be verified with information given on VECI label. |
The cover of the fuel filter is equipped with the bilateral safety valve. In case of refusal systems the valve provides withdrawal of fuel evaporations in the atmosphere.
Other dvukhkhodovy locking valve is installed on the fuel tank and provides adjustment of withdrawal of fuel evaporations in a coal adsorber depending on the differences of pressure/depression connected with change of temperature.
After passing of the double-thread valve fuel evaporations on ventilating hoses get to a coal adsorber in which accumulate during the whole time of the parking.
At start of the engine until its warming up up to the certain temperature the locking electromagnetic valve of a purge of an adsorber remains closed, allowing opening of the diaphragm valve of a purge due to increase in depth of depression in the inlet pipeline. From an adsorber fuel evaporations via the diaphragm valve are blown in the inlet pipeline from where come to combustion chambers where are burned out in the course of normal functioning of the engine.
Check
|
|
Full check of the EVAP system lies outside qualification of the average amateur mechanic. Fortunately, the EVAP system, as well as other systems of decrease in toxicity of the fulfilled gases, is protected by additional guarantee certificates for a period of 5 years / 80 000 km of a run. Most often failures of the system of EVAP are connected by damage of an adsorber or failure of vacuum hoses. |
Vacuum hoses
|
|
| 1. First of all always check a condition of vacuum hoses, damage or a detachment of most of which often and is a system cause of failure (be verified with the scheme of the laying of hoses given on a label of VECI of your car). In case of need replace the damaged hoses. |
|
Electromagnetic valve of management of a purge
|
|
1. The electromagnetic valve of management of a purge provides removal of the accumulated evaporations from a coal adsorber due to the depression created in the inlet pipeline. The valve provides giving of depression at the heated-up engine and remains closed at cold.
2. Make sure that temperature of the engine does not exceed specified on the electromagnetic valve:
73 °C for models 1994 and 1995 of of the issue.
68 °C for models since 1996 of the issue.
|
|
3. Find a purge hose in the top part of a coal adsorber (see an accompanying illustration). For a guarantee be verified with the scheme of the laying of hoses given on VECI label.
|
4. Having found the necessary hose, disconnect it from an adsorber and connect to the vacuum gage. Start the engine on single turns – depression should not be created.
5. Wait for warming up of the engine – now depression has to appear.
6. At negative results of check find the electromagnetic valve of management of a purge on the inlet pipeline and disconnect from it an electrical wiring. Disconnect vacuum hoses and connect a piece of a rubber hose to one of valve unions.
7. By means of wires crossing points connect the valve directly to the battery. Try to blow the valve through a hose. At the connected battery the valve has to be open and be blown freely, at disconnected – is closed (on some models the opposite scheme of functioning of the valve is used).
8. At negative results of check replace the electromagnetic valve. |
|
Dvukhkhodovy valve
|
|
1. Uncover the fuel filter.
|
|
2. Disconnect the line of fuel evaporations from a gasoline tank and connect the T-shaped union to the vacuum pump and the vacuum gage (see an accompanying illustration).
|
3. Slowly and continuously lifting depression depth, track indications of the vacuum gage. Depression has to be stabilized instantly on value 5.1÷15.2 of mm of mercury. If the valve opens earlier, than the required depression depth will be reached, replace it.
4. Switch the vacuum pump to the pressure head union. Lift pressure in the line and consider the indication of the vacuum gage. Pressure has to be stabilized in the range of 10.2÷35.6 mm of mercury. (the valve is open).
5. If the valve opens earlier, than the required depression depth will be reached, replace it. |
|
Locking valve of ventilation of a coal adsorber
|
|
1. To define whether your car is equipped with the locking valve of ventilation of an adsorber, look at the last from above. If on a cover there is a 2-contact electric socket, therefore the valve is provided.
2. Walk on a hose from the valve down to the three-running valve, assembly from an adsorber. Disconnect a hose from the three-running valve and connect it to the vacuum pump.
3. Remove the locking valve from an adsorber, without disconnecting from it an electrical wiring and the vacuum pump.
4. Include ignition (without starting the engine) and create depression in a hose. If the valve holds depression, disunite the electric socket. If the valve still remains locked, replace it. |
|