* Crankshaft Position Sensor (CKP): This sensor tells the engine's computer where the crankshaft is in its rotation cycle. A faulty CKP sensor will lead to erratic running or no running at all, often exhibiting the symptoms you describe. It's a relatively inexpensive part to replace, so it's worth checking or replacing.
* Camshaft Position Sensor (CMP): Similar to the CKP sensor, a faulty CMP sensor won't allow the engine to properly time the fuel injection and ignition. This can result in the engine starting but quickly dying.
* Throttle Position Sensor (TPS): This sensor tells the computer the throttle's position. A faulty TPS can cause erratic idle and stalling, as the computer won't receive accurate information about how much fuel to deliver.
* Mass Airflow Sensor (MAF): Measures the amount of air entering the engine. A dirty or faulty MAF sensor can provide incorrect data to the engine computer, leading to poor fuel mixture and stalling. Try cleaning it first (with MAF sensor cleaner, *not* carb cleaner) before replacing it.
* Ignition System (coils, wires, distributor): Though less likely given the initial running, a weak spark can cause the engine to die once the initial spark energy is depleted. Inspect the ignition wires for cracks or damage. Weak ignition coils can also exhibit similar symptoms. (Note: The GTP may not *have* a distributor; it depends on the engine. If it has coil packs instead, focus on the coil packs and wiring.)
* Fuel Pressure Regulator: Although you replaced the fuel pump, a faulty fuel pressure regulator could cause fuel pressure to drop too quickly after the initial start.
* Computer Issues: While less common, a problem with the engine control module (ECM) or related wiring could be the cause. This is a more difficult diagnosis.
Troubleshooting Steps:
1. Check for Diagnostic Trouble Codes (DTCs): Use an OBD-II scanner to read any stored trouble codes. This is the *first* step. The codes will give you a much better indication of the problem area.
2. Visual Inspection: Examine all wiring related to the fuel system, ignition system, and sensors mentioned above. Look for any loose connections, corrosion, or damaged wires.
3. Check Fuel Pressure: If possible, check the fuel pressure after starting the car. It should remain stable.
4. Test Sensors: While you can test some sensors with a multimeter, others require specialized equipment. If you're not comfortable doing this, take it to a mechanic.
5. Professional Diagnosis: If you've checked the easy things and still can't find the problem, take your car to a qualified mechanic. They have the tools and expertise to diagnose more complex issues.
Remember safety first! Always disconnect the negative battery terminal before working on the electrical system of your car. If you are not comfortable working on your car yourself, consult a professional mechanic.
