Fuel Evaporation System: Operation
When the engine is off, float bowl vent valve opens. Fuel vapors from fuel tank and carburetor collect in charcoal canister. When engine is running, float bowl vent valve closes and engine vacuum is applied to canister. This draws ambient air through purge valve, canister, and canister purge line into the carburetor.
A fuel recirculation system prevents fuel in lines from absorbing engine compartment heat, minimizing possibility of fuel evaporation.