Fuel Injected Engines

When fuel tank pressure exceeds a preset value, two-way valve opens and allows excess vapor to vent into canister. If excessive vacuum forms in fuel tank, two-way valve opens and outside air enters fuel tank through canister. Fuel filler cap acts as a safety valve if evaporation system fails.

When thermo valve temperature exceeds 131°F/55°C manifold opens purge control valve. When purge control valve is open, engine vacuum draws vapor from canister to throttle body. When temperature is below this value manifold vacuum is not applied to purge control valve.