* Fuel Pump Itself: The most likely culprit, despite replacing related parts. The pump might be weak, intermittently failing, or failing to prime properly. It's possible a new pump is needed. A fuel pressure gauge is crucial here to measure actual fuel pressure at the rail. Low or inconsistent pressure confirms a pump issue.
* Fuel Pump Relay: This electrical component controls the pump's power. A failing relay might supply intermittent power, causing the starting problems. Testing the relay's operation is easy and inexpensive.
* Crank Sensor/Cam Sensor: These sensors tell the engine's computer when the engine is turning over. A faulty sensor could prevent the fuel pump from activating even if everything else is working. Diagnostic trouble codes (DTCs) can help determine if this is the case.
* Wiring: Look for any damaged, corroded, or loose wiring related to the fuel system, especially near the pump and relay. A broken wire could interrupt power to the pump.
* Inertia Switch: Some cars have an inertia switch that cuts power to the fuel pump in a collision. Check if this is activated and reset it.
* Fuel Pressure Regulator: While less likely, a faulty fuel pressure regulator could cause inconsistent fuel pressure, leading to starting problems.
* ECU (Engine Control Unit): Though less probable, a faulty ECU could cause the fuel pump to malfunction. This is usually a more expensive and involved diagnostic process.
Troubleshooting Steps:
1. Check Fuel Pressure: This is the most important step. Use a fuel pressure gauge to measure the pressure at the fuel rail. The specification should be in your owner's manual or online. Low or fluctuating pressure points to a fuel delivery problem.
2. Test Fuel Pump Relay: A simple test can be done with a multimeter to check if the relay is getting power and switching correctly.
3. Check for DTCs: Use an OBD-II scanner (or a code reader compatible with your 1993 model) to retrieve any diagnostic trouble codes stored in the ECU. These codes can pinpoint the source of the problem.
4. Inspect Wiring: Carefully examine all wiring related to the fuel system for any damage.
5. Check Inertia Switch (if applicable): Locate the inertia switch and ensure it hasn't tripped.
Starting with ether is a dangerous workaround that masks the real problem. Don't rely on it. A proper diagnosis using a fuel pressure gauge and a code reader will be much safer and more effective in identifying the root cause of the starting issue. If you lack experience with automotive diagnostics, it's best to take the vehicle to a qualified mechanic.
