EVAP System

EVAP System

• Hose connections are secured with either spring type or clamp type clamps.

• Hose clip pliers (VAS 6340) or (VAS 6362) are recommended for installing space saving clamps.

The connector couplings for the fuel, vacuum and ventilation lines are color coded. There is either a colored dot on the connector or the release button is the corresponding color.






Evaporative Emission (EVAP) System

Depending on air pressure and ambient temperature, varying quantities of fuel vapors form above the fuel surface in the fuel tank.

The EVAP system prevents these Hydrocarbon (HC) emissions from entering the atmosphere.

With quantity restrictions, fuel vapors travel from the highest point of the fuel tank via the gravity valve (closed at a tilt of 45°) and the pressure retention valve to the EVAP canister.

The activated charcoal in the canister stores these gases like a sponge.

While driving, with oxygen sensor control active (engine is warm), the EVAP canister purge regulator valve 1 (N80) , (also called the regeneration valve) is activated by the Engine Control Module (ECM) in pulses dependent on load and engine speed. The opening time is dependent on input signals.

When purging (recovery of the activated charcoal), the suction tube vacuum sucks fresh air in through the ventilation opening on the underside of the EVAP canister. The fuel vapors stored amongst the activated charcoal and fresh air are proportionately supplied to be burned.

The pressure retention valve prevents fuel vapors from being sucked out of the tank when the EVAP canister purge regulator valve 1 is opened and an intake manifold vacuum is present. It therefore ensures that the evacuation of the EVAP canister has priority.

When no voltage is applied (for example, an open wiring circuit), the solenoid valve is closed. The EVAP canister is not purged.