Fuel Pressure Release: Service and Repair

WARNING: Fuel supply lines will remain pressurized for long periods of time after engine shut down. This pressure must be relieved before attempting to service the fuel system.


1. On 4-116, V6-232 and V8-302 CFI engines, a valve is provided on the throttle body to relieve system pressure. This valve can be located by removing the air cleaner assembly.
2. On 4-140 turbocharged EFI engines, the fuel system pressure relief valve is located in the flexible fuel supply tube approximately 12 inches back from where it connects to the engine fuel rail assembly.
3. To relieve fuel system pressure on CFI equipped engines, use pressure gauge tool T80L-9974-A or equivalent, and drain fuel pressure system through the drain tube assembly provided.
4. The pressure relief valve on EFI equipped engines is located in the engine compartment on the fuel supply line except on Capri, Cougar, Mustang and Thunderbird models. On these models the valve is located on the driver's side of the engine compartment in the flexible hose assembly which connects to the fuel rail on the engine.
5. Before opening the fuel system on EFI equipped engines, relief pressure as follows:

a. Remove fuel tank cap.
b. Disconnect vacuum hose from fuel pressure regulator located on the engine fuel rail.
c. Using a suitable hand held vacuum pump, apply approximately 25 inches Hg (negative pressure) to the pressure regulator.
d. Fuel pressure will be released into the fuel tank through the fuel return hose.