Fuel Evaporation System: Operation

When engine is off, vapor from tank is vented through relief valve to canister. When coolant temperature rises over 140°F (60°C) on turbo models and 86°F (30°C) on non-turbo models, thermoswitch contacts close to energize and open purge valve. This allows manifold vacuum to draw canister vapor through purge valve and into combustion chambers for burning.