Fuel System:
* Clogged Fuel Filter: Restricts fuel flow to the engine. A relatively inexpensive and easy fix.
* Faulty Fuel Pump: May be weak or failing, not providing sufficient fuel pressure.
* Fuel Injectors: Clogged or malfunctioning injectors prevent proper fuel delivery.
* Low Fuel Level: Obvious, but sometimes overlooked!
Ignition System:
* Crankshaft Position Sensor (CKP): Tells the engine's computer where the crankshaft is, essential for ignition timing. A faulty sensor will cause stalling.
* Cam Position Sensor (CMP): Similar to the CKP, but for the camshaft. A faulty CMP can lead to misfires and stalling.
* Ignition Coil: Provides the spark to ignite the air/fuel mixture. A failing coil can cause misfires and stalling, especially under load.
* Spark Plugs/Wires: Worn or damaged spark plugs and wires can prevent proper ignition.
* Ignition Switch: A faulty ignition switch can interrupt power to the ignition system.
Other Electrical Issues:
* Mass Airflow Sensor (MAF): Measures the amount of air entering the engine. A faulty MAF sensor can cause the engine to run lean or rich, leading to stalling.
* Throttle Position Sensor (TPS): Tells the engine's computer the throttle position. A faulty TPS can cause erratic idle and stalling.
* Computer (PCM/ECM): The engine control module can malfunction and cause various problems, including stalling. This is usually a last resort diagnosis.
* Alternator/Battery: A failing alternator won't charge the battery, and a weak battery can cause the engine to stall. Check battery voltage.
* Wiring Issues: Corrosion, loose connections, or damaged wiring can interrupt power to vital components.
Vacuum System:
* Vacuum Leaks: Leaks in the vacuum lines can disrupt engine operation and cause stalling, especially at idle.
Other Mechanical Issues:
* Idle Air Control (IAC) Valve: Regulates idle speed. A faulty IAC valve can cause stalling, especially at idle.
* Transmission Problems (Automatic): In an automatic transmission, issues can cause the engine to stall or lose power.
Troubleshooting Steps:
1. Check the obvious: Fuel level, obvious vacuum leaks, and battery voltage.
2. Check engine codes: Use an OBD-II scanner to read any diagnostic trouble codes (DTCs) stored in the car's computer. This will often point to the culprit.
3. Visual inspection: Look for any obvious signs of damage, loose connections, or worn parts.
4. Systematic checking: Based on the engine codes or your observations, start checking the components listed above in a logical order.
It's crucial to get a proper diagnosis. Attempting to fix the problem without proper knowledge can lead to further damage or injury. A qualified mechanic with experience in older vehicles will be able to diagnose the problem effectively and efficiently.
