Ford Mustang 1989-1993 Repair Guide

Relieving Fuel System Pressure


All EFI and SEFI fuel injected engines are equipped with a pressure relief valve located on the fuel supply manifold. Remove the fuel tank cap and attach fuel pressure gauge T80L-9974-A, or equivalent, to the valve to release the fuel pressure. If a pressure gauge is not available, disconnect the vacuum hose from the fuel pressure regulator and attach a hand vacuum pump. Apply about 25 in. Hg (84 kPa) of vacuum to the regulator to vent the fuel system pressure into the fuel tank through the fuel return hose. Note that this procedure will remove the fuel pressure from the lines, but not the fuel. Take precautions to avoid the risk of fire and use clean rags to soak up any spilled fuel when the lines are disconnected.