Ventilation Valve

The ventilation valve is controlled with intake manifold vacuum. When engine is not running or running at wide open throttle, and intake manifold vacuum pressure is below 2.36-2.75 inches Hg, the valve is opened to allow fuel vapor to enter the charcoal canister. When engine is running and intake manifold vacuum pressure is over 2.36-2.75 inches Hg, the valve is closed.