Pickup & 4RUNNER - CARBURETED

When the engine is not running, fuel tank vapor flows through vent line into canister for storage. Float bowl vapor flows through outer vent control valve into canister for storage when ignition is off.

When engine is running (above 16 MPH with coolant temperature above 131°F (55°C), the vacuum switching valve (VSV) opens to allow canister vapor to be drawn into intake manifold for burning. The VSV is an electrically operated solenoid-type valve that is opened and closed by the emission computer. The computer opens and closes the valve based upon input signals from the speed sensor and/or temperature switch.