1. Fuel System:
* Fuel Pump: A failing fuel pump can't deliver enough fuel to the engine. Listen for the hum of the fuel pump when you turn the key to the "on" position (before cranking). No hum suggests a possible pump failure.
* Fuel Filter: A clogged fuel filter restricts fuel flow. This is a relatively inexpensive part to replace and a good first check.
* Fuel Injectors: Clogged or faulty injectors won't spray fuel properly. Diagnosing this typically requires a fuel pressure test and potentially injector testing.
* Fuel Pressure Regulator: A faulty regulator can cause inconsistent fuel pressure.
2. Ignition System:
* Crankshaft Position Sensor (CKP): This sensor tells the computer the engine's rotational position. A faulty CKP will prevent the engine from running.
* Camshaft Position Sensor (CMP): Similar to the CKP, but for the camshaft. A faulty CMP also prevents proper engine operation.
* Ignition Coil(s): These supply the high voltage needed for spark plugs. A bad coil will cause misfires or prevent starting/running in one or more cylinders.
* Spark Plugs and Wires: Worn or damaged spark plugs or wires can lead to misfires and a rough running engine or failure to start.
* Ignition Switch: A failing ignition switch might not provide consistent power to the ignition system.
3. Air Intake System:
* Mass Airflow Sensor (MAF): A dirty or faulty MAF sensor provides inaccurate air flow readings to the computer, leading to poor running or stalling. Try cleaning it first (with MAF sensor cleaner).
* Air Filter: A severely clogged air filter restricts airflow and can cause poor engine performance or stalling.
4. Electrical System:
* Battery: A weak or failing battery can cause the engine to stall, especially under load. Test the battery's voltage.
* Alternator: The alternator charges the battery. A failing alternator won't recharge the battery, eventually leading to stalling. Test the alternator's output voltage.
* Wiring and Connections: Corrosion or loose connections in the electrical system can interrupt power to crucial components. Inspect all wiring and connections, particularly in the engine bay.
* PCM (Powertrain Control Module): A faulty PCM can cause a wide range of problems, including stalling. This is usually a last resort diagnosis.
Troubleshooting Steps:
1. Start with the basics: Check the battery voltage, fuel level, and air filter.
2. Listen for the fuel pump: Turn the key to "on" (without cranking).
3. Check for error codes: Use an OBD-II scanner to read any diagnostic trouble codes (DTCs) stored in the PCM. This can often pinpoint the problem.
4. Visual inspection: Look for any obvious signs of damage or loose connections in the engine bay.
5. Systematic testing: Based on the initial checks and any DTCs, systematically test the components listed above. This may require specialized tools or the assistance of a mechanic.
Important Note: If you're not comfortable working on your vehicle yourself, take it to a qualified mechanic for diagnosis and repair. Improperly diagnosing and repairing automotive issues can be dangerous.
