Fuel System:
* Clogged Fuel Filter: A restricted fuel filter prevents sufficient fuel from reaching the engine, leading to stalling. This is a relatively inexpensive and easy fix.
* Fuel Pump Failure: The fuel pump might be failing to deliver enough fuel pressure. This could be due to age, wear, or a faulty relay. A weak pump might work intermittently, causing the car to cut off.
* Bad Fuel Injectors: Clogged or malfunctioning fuel injectors can prevent proper fuel delivery to the cylinders. This is a more expensive repair.
* Low Fuel Pressure: Issues in the fuel lines, pressure regulator, or other components can cause low fuel pressure.
Ignition System:
* Crankshaft Position Sensor (CKP Sensor): This sensor tells the engine's computer the position of the crankshaft. A faulty sensor will cause the engine to cut off or not start at all.
* Cam Position Sensor (CMP Sensor): Similar to the CKP sensor, but for the camshaft. A faulty CMP sensor can lead to erratic engine operation and stalling.
* Ignition Coil(s): Worn or damaged ignition coils can fail to deliver the high voltage needed to ignite the fuel-air mixture.
* Distributor Cap and Rotor (if equipped): These components distribute the high voltage to the spark plugs. Cracks or corrosion can cause misfires and stalling.
* Spark Plugs and Wires: Worn or fouled spark plugs and damaged wires can prevent proper ignition.
Electrical System:
* Alternator: If the alternator is failing, the battery may not be charged, eventually leading to the engine dying.
* Battery: A weak or failing battery can cause the engine to cut off, especially under load (e.g., using headlights or air conditioning). Test the battery voltage.
* Faulty Wiring: Damaged or corroded wiring can disrupt the electrical signals needed for proper engine operation. This is often difficult to diagnose.
* Computer/ECM Problems: The engine control module (ECM) controls many aspects of the engine. A faulty ECM can lead to a wide range of problems, including stalling. This is usually a last resort diagnosis.
Other Possibilities:
* Throttle Position Sensor (TPS): A faulty TPS can cause the engine to misbehave and even stall.
* Mass Airflow Sensor (MAF Sensor): This sensor measures the amount of air entering the engine. A faulty MAF sensor can cause the engine to run poorly and stall.
* Vacuum Leaks: Leaks in the vacuum system can disrupt the engine's operation and cause stalling.
Troubleshooting Steps:
1. Check the obvious: Start with the simplest things: fuel level, battery voltage, and look for any obvious signs of damage or leaks.
2. Check engine light: If the check engine light is on, have the codes read at an auto parts store or mechanic. This will give you valuable clues.
3. Listen for unusual noises: Listen carefully for unusual sounds coming from the engine compartment. A clicking sound might indicate a fuel pump issue.
4. Get a professional diagnosis: If you're not comfortable working on cars yourself, take it to a qualified mechanic. They have the tools and experience to diagnose the problem accurately.
It's difficult to pinpoint the exact cause without more information about the symptoms (does it cut off immediately, after driving for a while, etc.? Does it restart easily?), but this list covers the most common possibilities. Start with the simpler checks and work your way down the list. Remember safety first – always disconnect the battery before working on any electrical components.
