Here's a breakdown of the most common culprits:
Fuel Delivery Issues:
* Fuel pump: A failing fuel pump can't provide sufficient pressure, leading to stalling, especially under load (e.g., acceleration or climbing hills). Listen for a weak or intermittent whirring sound from the fuel pump when the key is turned on.
* Clogged fuel filter: A clogged filter restricts fuel flow, leading to insufficient fuel reaching the engine.
* Fuel injectors: Clogged or malfunctioning fuel injectors prevent proper fuel atomization and delivery. This can cause intermittent stalling or hesitation.
* Low fuel level: This is the most obvious, but sometimes easily overlooked.
Ignition System Problems:
* Distributor cap and rotor (if applicable): Cracks or corrosion in these parts can disrupt the spark delivery to the cylinders, causing misfires and stalling. (This is more relevant to older, distributor-equipped engines).
* Ignition coil: A failing coil won't produce the necessary high voltage spark for combustion.
* Spark plugs and wires: Worn, fouled, or damaged spark plugs or wires will hinder efficient ignition.
* Crankshaft position sensor (CKP sensor): This sensor tells the ECU the engine's rotational position, crucial for timing the spark. A faulty CKP sensor can cause misfires and stalling.
* Cam position sensor (CMP sensor): Similar to the CKP sensor, a faulty CMP can lead to erratic ignition timing.
* Ignition control module (ICM): In older systems, a failing ICM can prevent proper spark delivery.
Vacuum Leaks:
* Vacuum hoses: Cracked or disconnected vacuum hoses can disrupt the engine's operation, impacting things like the fuel system or other critical functions. Listen carefully for unusual hissing sounds.
* Intake manifold gasket: A leak in this gasket can cause a major vacuum loss.
Other Possible Causes:
* Throttle Position Sensor (TPS): A faulty TPS sends inaccurate information about throttle position to the ECU, potentially causing stalling.
* Mass Airflow Sensor (MAF sensor): An inaccurate MAF sensor reading can lead to improper fuel mixture, resulting in stalling.
* Computer (PCM/ECM): While less common, a faulty engine control module can cause a wide range of problems, including stalling.
Troubleshooting Steps:
1. Check the basics: Fuel level, obvious vacuum leaks (listen for hissing), and easy-to-access components like spark plug wires.
2. Listen for unusual noises: Weak fuel pump whirring, hissing vacuum leaks.
3. Check engine codes: Use an OBD-II scanner to read any diagnostic trouble codes (DTCs) stored by the engine control module. These codes can give valuable clues.
4. Professional Diagnosis: If you can't pinpoint the problem, a qualified mechanic with diagnostic tools is essential. They can perform more in-depth tests to identify the faulty component.
Without more information about the specifics of the stalling (gradual, sudden, under load, etc.), it's impossible to give a definitive answer. The above list covers the most frequent possibilities. Remember safety first – always disconnect the battery negative terminal before working on the electrical system.
