Troubleshooting a no-start situation (assuming the fuel pump is working):
1. Check the fuel pump: Listen for the fuel pump whirring when you turn the key to the "ON" position (not cranking). You should hear a brief hum. If you don't hear it, you may have a faulty pump, relay, or wiring problem.
2. Check the fuel pressure: You'll need a fuel pressure gauge to measure the pressure at the fuel rail. The specification for the fuel pressure is printed in your owner's manual or can be found online in repair manuals for that specific year and model. Low or no pressure points to a fuel delivery problem.
3. Check the fuel injectors: This is more advanced and typically requires specialized tools and knowledge. If fuel pressure is good but the engine still won't start, the injectors may be clogged or faulty. A mechanic should handle this.
4. Check the ignition system: A no-start condition isn't always fuel related. Issues with the distributor, ignition coil, spark plugs, wires, or crankshaft position sensor can also prevent the engine from starting.
5. Check the computer (EEC-IV): The 1986 5.0L uses an electronic engine control system (EEC-IV). A malfunctioning computer can cause a wide range of problems, including a no-start condition. Diagnostic codes might need to be read with a scan tool.
In summary: There's no manual priming involved. Focus on diagnosing why the engine isn't starting, starting with the fuel pump and fuel pressure. If you're not comfortable working on fuel systems or the ignition system, it's best to take your vehicle to a qualified mechanic. Working with fuel systems involves potential fire hazards.
