A car that starts and then dies almost immediately is typically caused by a failure in one of three core systems: fuel delivery, air intake, or ignition spark. The most common culprits are a faulty fuel pump, a clogged fuel filter, a malfunctioning mass airflow (MAF) sensor, or issues with the anti-theft security system. The engine needs a precise mix of fuel and air, ignited by a spark, to continue running after the initial start-up sequence.
To diagnose the issue, start with the simplest checks. Listen for a faint whirring sound from the fuel tank when you turn the key to the "on" position (without cranking the engine). That's the fuel pump priming the system. If you don't hear it, the pump or its relay might be faulty. A clogged fuel filter restricts flow, starving the engine after the initial fuel in the line is used up.
Next, consider sensors. The Mass Airflow Sensor (MAF) measures the air entering the engine. If it's dirty or broken, the car's computer (ECU) can't calculate the correct fuel amount, causing the engine to stall. Similarly, a failed crankshaft position sensor tells the ECU the engine has stopped, cutting fuel and spark.
Don't overlook the anti-theft system. If the car doesn't recognize the key's chip, it will allow the engine to start but then cut fuel almost instantly, often accompanied by a security light on the dashboard.
| Potential Cause | Symptom Description | Common Fix/Diagnosis |
|---|
| Failing Fuel Pump | Whining noise from tank, loss of power under load. | Check fuel pressure with a gauge. |
| Clogged Fuel Filter | Engine sputters under acceleration before stalling. | Replace filter (often a maintenance item). |
| Faulty Mass Airflow Sensor | Rough idle, poor acceleration, stalling when coming to a stop. | Clean with MAF cleaner or replace. |
| Bad Crankshaft Position Sensor | No tachometer reading while cranking, intermittent stalling. | Test sensor resistance or replace. |
| Ignition Switch Problems | Stalling when hitting a bump, electrical flickering. | Inspect switch for wear or loose connections. |
| Vacuum Leak | Hissing sound under hood, high or fluctuating idle. | Use propane or smoke machine to find leak. |
| Faulty Idle Air Control Valve (IAC) | Engine won't idle without foot on gas, stalls in gear. | Clean or replace the IAC valve. |
| Anti-Theft System Issue | Security light stays on/blinks, starts then dies immediately. | Try a spare key, or reset/program system. |
For most of these issues, especially those involving sensors or the fuel system, using an OBD-II scanner to check for trouble codes is the most efficient first step. It can quickly point you toward the specific system that's failing.
