Fleetwood Brougham V8-252 4.1L (1985)
Fuel Tank Pressure Release Valve: Description and Operation
This valve is a spring based diaphragm valve which normally closed. When vapor pressure in the fuel tank exceeds a predetermined pressure, the
valve will open allowing the vapors to vent to the canister and then be purged. When tank pressure drops sufficiently, the tank pressure control valve will
close, keeping vapors in the fuel tank.