Evaporative emission control

EVAPORATIVE EMISSION CONTROL

1. Fuel tank
2. Filler neck breather pipe
3. Filler cap
4. Two-way breather valve
5. Evaporative emission cannister

Evaporative Emission Cannister

The evaporative emission (EVAP) cannister contains charcoal which absorbs and stores fuel vapour from the fuel tank while the engine is not running. When the engine is running the vapour is purged from the cannister into the engine and burned.

The EVAP cannister is purged when the EVAP cannister purge valve is opened. Manifold depression draws fresh air into the cannister through the charcoal, which releases fuel vapour into the throttle housing.

6. Evaporative emission cannister, purge valve
7. Vent line
8. Fuel release line
9. Air intake line

Evaporative Emission Cannister, Purge Valve

An EVAP cannister, purge valve is operated by the ECM. The purge valve remains closed when the engine is cold or at idling speed, to protect engine tune and catalyst performance. If the EVAP cannister was purged during cold running or at idling speed, the additional enrichment in fuel mixture would delay catalyst light off time and cause erratic idling. When the engine is above 75°C, the purge valve solenoid will become operational (modulated ON and OFF) whenever the engine speed is above approximately 1800 rev/min. When the purge valve is opened, fuel vapour from the EVAP cannister is drawn into the throttle housing for combustion.