Fuel Evaporation System: Operation

When engine is not running, fuel vapor from fuel tank flows to carbon canister for storage. 3-way valve prevents excessive prevents excessive pressure or vacuum from forming in system.

When engine coolant temperature reaches about 131°F/55°C, water thermo valve opens and intake manifold vacuum is directed to purge control valve(s). When manifold vacuum opens purge control valve, fresh air is drawn through inlet hole at bottom of canister. Vapor is drawn into engine and burned.