Vacuum Controlled Orifice Tank Vapor Valve

1985-87 L4-135, 4-156 & 1987 V6-238 ENGINES
The vacuum controlled orifice tank vapor valve is located in the fuel tank vent line to the charcoal canister. When the engine is not operating, the valve will remain closed, retaining fuel vapor in the fuel tank until pressure reaches the calibrated level, at which time the valve will open and allow fuel vapor to vent from the tank to the canister. When the engine is operating, manifold vacuum is applied to the valve signal port, opening the valve to allow fuel vapor to vent to the canister.