Fuel Evaporation System: Operation

When engine is not running, fuel vapors from fuel tank flow to carbon canister for storage. When key is off, float bowl is vented to canister (GLC and 626). Check and cut valve (if equipped) prevents excessive pressure or vacuum from forming in system. When engine is started on B2000, manifold vacuum opens evaporative shutter valve to allow fresh air into carburetor.

On all models, when engine coolant temperature reaches approximately 122°F (50°C), water thermo valve opens and intake manifold vacuum is directed to purge control valve. When manifold vacuum opens purge control valve, fresh air is drawn through inlet hole at bottom of canister. Vapors are drawn into engine and burned.