Fuel System Issues:
* Fuel Pump: A failing fuel pump might provide adequate pressure at idle but not under load. When you accelerate, the demand for fuel increases, and a weak pump can't keep up, leading to fuel starvation and engine shutdown.
* Fuel Filter: A clogged fuel filter restricts fuel flow, similar to a weak fuel pump.
* Fuel Pressure Regulator: A faulty regulator might not maintain the correct fuel pressure, causing inconsistent fuel delivery.
* Clogged Fuel Injector(s): A blocked or malfunctioning injector(s) can starve a cylinder(s) of fuel, causing the engine to stall, especially under load.
* Fuel Pump Relay: A faulty relay might not be supplying power to the fuel pump consistently.
Ignition System Issues:
* Crankshaft Position Sensor (CKP): This sensor tells the computer the engine's rotational speed and position. A failing CKP sensor can cause the engine to cut out, especially under load.
* Cam Position Sensor (CMP): Similar to the CKP, a faulty CMP sensor disrupts the timing of the engine, leading to stalling.
* Ignition Coil(s): A failing coil can't provide the necessary spark to ignite the fuel-air mixture in the cylinders. This often manifests as misfires that can escalate to a complete stall.
* Ignition Module: This component controls the ignition coils. A faulty module can cause intermittent or complete ignition failure.
* Distributor Cap and Rotor (if equipped): Worn or damaged components can lead to poor spark delivery.
Electrical System Issues:
* Alternator: A failing alternator can't recharge the battery. If the battery voltage drops too low, the engine will cut out. This is often accompanied by warning lights on the dash.
* Battery Cables/Connections: Corroded or loose battery cables can cause poor electrical connections, resulting in intermittent power loss.
* Wiring Issues: Damaged or frayed wiring, particularly in the engine bay, can cause intermittent shorts or breaks, leading to engine failure.
* PCM (Powertrain Control Module): While less common, a faulty PCM can cause a variety of issues, including stalling. This is a more difficult diagnosis and often requires specialized tools.
Other Potential Causes:
* Throttle Position Sensor (TPS): A faulty TPS provides incorrect information to the PCM about throttle position, leading to erratic engine behavior and potential stalling.
* Mass Airflow Sensor (MAF): A malfunctioning MAF sensor provides inaccurate readings of the air intake, causing the engine to run lean or rich and potentially stall.
* Vacuum Leaks: Leaks in the vacuum system can disrupt engine operation and cause stalling.
* Overheating: If the engine overheats, the computer may shut the engine down to prevent damage. Check coolant levels and look for signs of overheating.
Troubleshooting Steps:
1. Check for trouble codes: Use an OBD-II scanner to retrieve any diagnostic trouble codes (DTCs) stored in the PCM. These codes can provide valuable clues.
2. Check the obvious: Inspect battery connections, fluid levels (oil, coolant, brake fluid), and look for any obvious signs of damage or leaks.
3. Listen for unusual noises: Listen carefully for unusual noises coming from the engine, such as knocking, ticking, or whining sounds.
4. Test the fuel pressure: A fuel pressure gauge can help determine if the fuel system is delivering adequate pressure.
5. Check the ignition system: Inspect spark plug wires, distributor cap and rotor (if applicable), ignition coil(s), and spark plugs for signs of damage or wear.
This problem requires systematic troubleshooting. Starting with the simplest checks (battery, connections, fluid levels) and working your way through the more complex systems (fuel system, ignition system, PCM) is generally the best approach. If you're not comfortable working on your vehicle yourself, take it to a qualified mechanic for diagnosis and repair.
