1. Fuel System:
* Fuel Pump: A failing fuel pump can't deliver enough fuel to the engine. Listen for the fuel pump whirring when you turn the key to the "on" position (before cranking). A weak or absent whir suggests a failing pump.
* Fuel Filter: A clogged fuel filter restricts fuel flow. Replacing this is relatively inexpensive and should be done regularly as part of maintenance.
* Fuel Injectors: Clogged or faulty injectors prevent proper fuel delivery to the cylinders. Diagnosis usually requires specialized tools or a professional mechanic.
* Fuel Pressure Regulator: This regulates fuel pressure in the system. A faulty regulator can cause inconsistent fuel delivery.
2. Ignition System:
* Crankshaft Position Sensor (CKP): This sensor tells the computer the engine's rotational speed. A faulty CKP sensor prevents the engine from starting or causes stalling.
* Camshaft Position Sensor (CMP): Similar to the CKP sensor, but for the camshaft. A faulty CMP sensor can lead to misfires and stalling.
* Ignition Coil(s): These provide the spark to ignite the air/fuel mixture. A failing coil will cause misfires and potentially stalling. Spark plug wires can also be a source of ignition problems.
* Spark Plugs: Worn or fouled spark plugs prevent proper combustion. They should be inspected and replaced as needed (check your owner's manual for recommended intervals).
3. Air Intake System:
* Mass Airflow Sensor (MAF): This sensor measures the amount of air entering the engine. A dirty or faulty MAF sensor provides inaccurate readings to the computer, leading to poor fuel mixture and stalling. Cleaning the sensor (carefully, following instructions) can sometimes resolve the issue.
* Throttle Body: A dirty or sticking throttle body can restrict airflow. Cleaning the throttle body is a common maintenance task.
* Air Filter: A severely clogged air filter restricts airflow and can lead to poor engine performance and stalling.
4. Other Potential Issues:
* PCV Valve: A faulty PCV (Positive Crankcase Ventilation) valve can cause excessive pressure buildup in the crankcase, affecting engine performance.
* Computer Problems (PCM): While less common, a faulty PCM (Powertrain Control Module) can cause a variety of issues, including stalling. This usually requires professional diagnosis.
* Vacuum Leaks: Leaks in the vacuum system can disrupt engine operation.
* Alternator: A failing alternator can't maintain sufficient voltage, leading to stalling, especially when under load (like using accessories).
How to Approach Diagnosis:
1. Check the Obvious: Start with the easiest and cheapest checks: air filter, spark plugs, and fuel filter. Replace these if necessary.
2. Listen and Observe: Pay attention to any unusual sounds (whirring, clicking, knocking) when the engine starts or stalls.
3. Check Engine Light: If the check engine light is on, have the codes read using an OBD-II scanner. This will provide valuable clues about the problem.
4. Professional Help: If you're not comfortable working on your vehicle yourself, take it to a qualified mechanic. They have the tools and expertise to diagnose and repair the problem efficiently.
Without more specific information about when the stalling occurs (e.g., only at idle, after acceleration, under load), it's impossible to pinpoint the exact cause. The systematic approach above will help narrow down the possibilities.
