Fuel Evaporation System: Operation

When engine is off, vapor from tank is vented through relief valve to canister. When engine is running and cold on non-turbo models, a small amount of air is drawn through the canister orifice and into the intake manifold. On turbo models, when engine coolant is below 140°F (60°C), no vapor is vented through the engine.

When coolant temperature rises over 140°F (60°C), thermo valve opens the electrovalve (purge valve on non-turbo). This allows manifold vacuum to draw canister vapor through the electrovalve (purge valve) and into the combustion chambers for burning. When engine is operated at full throttle, vacuum drops and purging stops until load is reduced.