Fuel System:
* Fuel Pump: A failing fuel pump can't supply enough fuel to the engine, leading to stalling. This is more likely to happen under load (acceleration) or when the tank is low.
* Fuel Filter: A clogged fuel filter restricts fuel flow, causing similar problems to a failing fuel pump.
* Fuel Injectors: Clogged or malfunctioning fuel injectors can prevent proper fuel delivery to the cylinders.
* Fuel Pressure Regulator: A faulty regulator can cause inconsistent fuel pressure, leading to stalling.
Ignition System:
* Distributor Cap and Rotor: Worn or damaged components in the distributor can cause intermittent spark, resulting in stalling. (Especially common in older vehicles with distributors)
* Ignition Coil: A failing ignition coil won't generate the high voltage needed for spark.
* Spark Plugs and Wires: Worn or damaged spark plugs and wires can cause misfires and stalling.
* Crankshaft Position Sensor (CKP): This sensor tells the computer the engine's rotational speed. A faulty CKP sensor can cause the engine to stall, especially when the engine is hot.
Other Potential Causes:
* Mass Airflow Sensor (MAF): A faulty MAF sensor provides inaccurate air flow readings to the computer, leading to improper fuel mixture and stalling.
* Throttle Position Sensor (TPS): A malfunctioning TPS sensor won't give accurate throttle position information to the computer, resulting in poor fuel/air mixture.
* Vacuum Leaks: Leaks in the vacuum lines can disrupt the engine's operation and lead to stalling.
* Transmission Issues (Automatic): Problems within the transmission itself can cause the engine to stall, especially if there's a problem with the torque converter.
* Alternator: A failing alternator may not charge the battery sufficiently, leading to a stall once the battery voltage drops too low.
* Computer/ECM Problems: A faulty engine control module (ECM) can cause a wide range of problems, including stalling.
Troubleshooting Steps (in order of easiest to hardest):
1. Check the obvious: Look for any obvious signs of damage, loose wires, or anything out of place under the hood.
2. Check the battery and alternator: Have the battery and charging system tested at an auto parts store. A weak battery or failing alternator can cause stalling.
3. Inspect the fuel filter: Replace the fuel filter if it's old or dirty. This is a cheap and relatively easy fix.
4. Check for vacuum leaks: Visually inspect all vacuum hoses for cracks or damage. Listen for hissing sounds near the engine when it's running.
5. Check spark plugs and wires: Inspect the spark plugs for fouling or damage. Check the spark plug wires for cracks or damage.
6. Check the distributor cap and rotor (if applicable): Look for cracks, corrosion, or worn contacts.
Important Note: If you're not comfortable working on your car yourself, take it to a qualified mechanic for diagnosis and repair. Attempting to diagnose and repair complex automotive problems without experience can be dangerous and potentially lead to further damage. The more information you can give the mechanic (when the stalling occurs, what conditions precede it, etc.), the better equipped they'll be to pinpoint the problem.
