* Fuel System Problems:
* Fuel Pump: A weak or failing fuel pump might provide enough pressure for the initial start, but not enough to sustain it. Listen carefully near the fuel tank for a humming sound when the key is turned to "on" (before cranking). A weak hum or no hum suggests a failing pump.
* Fuel Filter: A clogged fuel filter restricts fuel flow. A relatively inexpensive and easy part to replace.
* Fuel Pressure Regulator: This regulates fuel pressure in the system. A faulty regulator can cause inconsistent fuel delivery.
* Clogged Fuel Injectors: Dirty or clogged injectors can prevent sufficient fuel from reaching the combustion chambers. This often requires cleaning or replacement.
* Fuel Pump Relay: The relay might be failing, preventing the pump from receiving power consistently.
* Ignition System Problems:
* Crankshaft Position Sensor (CKP): This sensor tells the computer the engine's rotational speed. A faulty CKP sensor can cause erratic running or stalling.
* Cam Position Sensor (CMP): Similar to the CKP sensor, but monitors the camshaft. A faulty CMP will also lead to misfires and stalling.
* Ignition Coil: Provides the spark to the spark plugs. A failing coil might provide a spark initially, but not consistently. Testing each coil individually is often necessary.
* Spark Plugs & Wires: Worn, fouled, or damaged spark plugs or wires can prevent a reliable spark.
* Ignition Control Module (ICM): This controls the ignition system. A failing ICM can cause intermittent starting and stalling.
* Other Potential Issues:
* Mass Airflow Sensor (MAF): A dirty or faulty MAF sensor provides inaccurate air readings to the engine computer, leading to poor fuel mixture and stalling.
* Throttle Position Sensor (TPS): A bad TPS provides incorrect information to the computer about the throttle position, leading to poor fuel delivery.
* Vacuum Leaks: Leaks in the intake manifold or vacuum lines can disrupt the air/fuel mixture.
Troubleshooting Steps:
1. Check for error codes: Use an OBD-II scanner to read any diagnostic trouble codes (DTCs) stored in the vehicle's computer. These codes can significantly narrow down the possibilities.
2. Listen for the fuel pump: As mentioned above, listen for the fuel pump's hum when the key is turned to "on."
3. Inspect spark plugs and wires: Check for visible damage, fouling, or wear.
4. Check for vacuum leaks: Visually inspect all vacuum lines and the intake manifold for cracks or loose connections.
Because you're describing an intermittent problem that begins after the initial start-up, the fuel pump, fuel pressure regulator, and the various sensors are the most likely candidates. I strongly recommend taking your vehicle to a qualified mechanic for diagnosis and repair. Trying to troubleshoot these issues without proper tools and experience can be time-consuming and potentially frustrating.
