Bowl Vent Valve: Description and Operation

The bowl vent valve is connected to the carburetor fuel bowl, charcoal canister and air pump outlet. When the engine is not operating, there is a direct connection between the fuel bowl and canister. When the engine is operating, air pump pressure closes the connection between the fuel bowl and canister. When the engine is switched off, air pressure in the valve bleeds off and the fuel bowl is allowed to vent into the canister.