Fuel supply lines on all fuel injected engines will remain pressurized for some period of time after the engine is shut OFF . This pressure must be relieved before servicing the fuel system. Pressure is relieved through the fuel pressure relief valve. To relieve the fuel system pressure, first remove the fuel tank cap to relieve pressure in the tank, then remove the cap on the fuel pressure relief valve, located on the fuel rail. Attach fuel pressure gauge T80L-9974-A or equivalent, and drain the system through the drain tube into a suitable container. Remove the fuel pressure gauge and replace the cap on the relief valve.