* Fuel Pump: The most common suspect. Even with pressure at the rail, the pump might be weak or intermittently failing. It might build pressure enough to register on a gauge but not deliver fuel consistently under engine load. Replace this before anything else.
* Fuel Injectors: Clogged or failing injectors might not be atomizing the fuel properly. Starting fluid bypasses the injectors, so this would explain the short-lived run. Testing injectors for proper spray pattern and flow is crucial.
* Fuel Filter: A clogged fuel filter can restrict fuel flow enough to cause problems, especially under demand. This is a cheap and easy part to replace.
* Pick-Up Tube (in the tank): If the pick-up tube in the fuel tank is damaged or clogged, the pump may not be able to draw fuel effectively.
* Check Valve (in the Pump or Line): A faulty check valve would allow fuel to flow back into the tank preventing sufficient pressure for engine running.
* Throttle Position Sensor (TPS) or Mass Airflow Sensor (MAF): While less likely given the starting fluid behavior, a faulty TPS or MAF sensor could prevent the computer from supplying the correct fuel pulse. Incorrect fuel delivery based on the sensor reading might explain the limited run time.
Why the fuel rail and regulator are less likely (but still possible):
* Fuel Rail: A problem with the fuel rail itself (leaks, cracks) would typically cause a fuel pressure loss, not just intermittent running.
* Fuel Pressure Regulator: A failing regulator might allow fuel to leak back into the return line, reducing pressure. However, a complete lack of pressure is more indicative than short-term running and the fact that it runs with starting fluid makes a regulator problem slightly less probable.
Troubleshooting Steps:
1. Check the Fuel Pump: Listen carefully near the fuel tank for the pump's hum when the key is turned to the "on" position (don't crank). A weak or no hum points to a bad pump. You can also check fuel pressure using a gauge while cranking – pressure should be within specification for your car.
2. Replace the Fuel Filter: It's cheap and easy to do, and a clogged filter is a common cause of intermittent fuel delivery.
3. Inspect the Fuel Injectors: This might require specialized tools for testing. You can sometimes visually inspect for leaks or spray patterns, but a professional test is preferred.
4. Check Fuel Pressure Consistently: If the fuel pressure seems okay initially, monitor it as the engine cranks. A drop in pressure during cranking is a major clue.
5. Inspect the Fuel Lines and Connections: Look for any obvious cracks, leaks, or loose connections.
6. Consider the TPS and MAF sensors: If all else fails, check the TPS and MAF, though these are less likely based on the symptom description.
Recommendation: Start with the simplest and cheapest solutions first (fuel filter, fuel pump). The symptoms strongly indicate a problem in the fuel delivery system *before* it reaches the injectors. A mechanic can run diagnostics if you're unable to troubleshoot these yourself.
