Bowl Vent Valve: Description and Operation

Bowl Vent System:

The bowl vent valve is used to isolate the float bowl fuel vapors from the atmosphere. When the engine is operating, intake manifold vacuum acts on the diaghragm to close the bowl vent valve so that the carburetor bowl is open to the air horn vent. When the engine is stopped, the bowl vent valve closes the air horn vent and opens a passage to the charcoal canister for storage of fuel vapors.