The fuel injection relay plays a big part in providing power to most of the fuel injection components. The F.I. relay provides power to the control unit, fuel injectors, and AFM. It also provides power to the fuel pump and aux air regulator when the ignition switch is in the "start" position. After the engine starts, the fuel pump gets it's power through the AFM when the ign sw is in the "on" position. Disconnect the starter solenoid lead so the engine will not start. Turn ign sw to "start". Listen for pump to run and the pressure regulator to buzz. If no sound, then it may be the relay. Check relay by placing hand on relay when in "start" position and feel for click. If no click, then check ign sw. Hope this helps Randy