* Fuel Pump: The most likely culprit. If the fuel pump fails or is weak, it can't supply enough fuel to the engine, especially when idling at a stop. The fuel cutoff light is a safety feature that often activates when the fuel system detects a problem, including low fuel pressure. A failing pump might work under higher RPMs (driving) but fail under low demand (idle).
* Fuel Pump Relay: This relay acts as a switch for the fuel pump. A faulty relay won't allow power to reach the pump, causing the same symptoms as a bad pump. It's a cheaper and easier component to test and replace than the pump itself.
* Inertia Switch: This safety device cuts off fuel supply in the event of a collision to prevent fire. It's usually located under the dash or in the engine bay. If it's tripped (accidentally or otherwise), it will need to be reset. This is usually a simple button to press.
* Other less likely possibilities (but worth considering if the above are ruled out):
* Crankshaft Position Sensor (CKP): A faulty CKP sensor won't allow the engine to get the timing information it needs to run smoothly, leading to stalling.
* Mass Airflow Sensor (MAF): A dirty or faulty MAF sensor provides incorrect air/fuel mixture readings.
* Throttle Position Sensor (TPS): A faulty TPS sensor could provide inaccurate information to the engine control unit (ECU), causing stalling.
* Low Fuel: While unlikely if the light is *on*, make sure the fuel tank isn't extremely low. Sometimes sensors can malfunction, but this is less likely than the other options.
Troubleshooting Steps:
1. Check the fuel level: Make sure you aren't simply running out of gas.
2. Locate and reset the inertia switch: If it's tripped, you'll likely hear a click when you reset it.
3. Check the fuel pump relay: This is usually a simple swap with a known good relay from another circuit (if you have the same type of relay) to see if it resolves the problem.
4. Listen for the fuel pump: When you turn the ignition key to the "on" position (but don't start the engine), you should hear a brief humming sound from the fuel pump in the back of the car. If you don't, the pump or relay is suspect.
5. Professional Diagnosis: If the above steps don't reveal the problem, it's best to take your car to a mechanic for proper diagnosis. They have tools to test fuel pressure and other components more accurately.
The fuel cutoff light being illuminated strongly points to a fuel system problem, making the fuel pump and relay the most likely culprits. Start with the simpler checks (inertia switch and relay) before tackling the fuel pump replacement, which is a more involved repair.
