Gasoline vapor recovery system (VAZ-21051)

The system uses a method of vapor capture by a carbon adsorber installed in the engine compartment. When the engine is not running, gasoline vapors from the separator are fed through a gravity valve into the adsorber, where they are absorbed by activated carbon. Then, when the engine is running, the adsorber is blown with air and the vapors are sucked out to the branch pipe 6 (see Fig. Central injection unit), and then into the inlet pipe for combustion during the working process.

The ECU controls the purge of the adsorber by turning on the electromagnetic valve 16 (see Fig. Electrical connection diagram of the injection system), located on the adsorber cover. When voltage is applied to the valve, it opens, releasing vapors into the intake pipe. The valve is controlled by pulse-width modulation. The valve turns on and off at a frequency of 16 times per second (16 Hz). The higher the air flow, the longer the duration of the valve activation pulses.

The ECU turns on the purge valve of the canister when all of the following conditions are met:

• coolant temperature above 80°C;
• the fuel supply management system operates in closed loop mode;
• the vehicle speed exceeds 21 km/h. After the valve is turned on, the speed criterion changes. The valve will turn off only when the speed drops to 9 km/h;
• the throttle valve opening exceeds 2%. This factor is of no further importance if it does not exceed 99%. When the throttle valve is fully opened, the ECU switches off the purge valve of the adsorber.

(The article is copied from the website: vazbook.ru)

Examination

1. Inspect the hoses and the canister. If there are cracks or damage to the housing, replace the canister with a new one.

2. If leaks occur, check the tightness of the hose connections. If fuel leaks from the adsorber, replace it with a new one.