Fuel Evaporation System: Operation

When engine is off, vapors from tank are vented through relief valve to canister. When engine is running and cold, a small amount of air is drawn through the canister orifice and into the intake manifold.

When coolant temperature rises over 104°F (40°C), thermocontact opens and vacuum flows to electrovalve, which opens and allows air to be drawn through canister. All vapors are then drawn into the engine and burned. When engine is operated at full throttle, vacuum drops and purging stops until load is reduced.