Problems with fuel delivery on an '87 5.0 HO usually stem from one of these areas:
* Inertia Switch: This safety device cuts power to the fuel pump in a collision. It's often located under the dash or in the engine bay and may need to be reset.
* Fuel Pump Relay (Part of the larger system): While not specifically a *fuel injection* relay, the fuel pump itself is controlled through a relay within the underhood fuse box. This relay is often part of a larger circuit that might include other components. A faulty relay here could prevent the pump from receiving power.
* EEC-IV (Engine Control Module): The computer itself controls the fuel pump. A faulty computer or a problem with its programming can prevent the fuel pump from activating. This is less likely, but possible.
* Wiring: Issues with the wiring harness between the computer, relay, and fuel pump are also possible culprits. A broken wire or corroded connection can disrupt the circuit.
* Fuel Pump itself: The fuel pump could simply be failing.
To troubleshoot, you'll need to:
1. Check the inertia switch: Reset it.
2. Test the fuel pump relay: You can swap it with a known good relay of the same amperage rating (check your owner's manual or a wiring diagram) to see if that fixes the problem.
3. Check the fuel pump's power: Use a multimeter to check for power at the fuel pump connector with the key on.
4. Inspect the wiring: Look for broken, corroded, or loose wires in the fuel pump circuit. A wiring diagram is essential for this step.
You won't find a part labeled "Fuel Injection Relay" for this car. Focus on testing the components and wiring I've mentioned above. A wiring diagram specific to your 1987 Mustang 5.0 HO is highly recommended for proper diagnosis. You can usually find these online through Mustang forums or repair manuals.
