What "Starts but Doesn't Run" Actually Means
When a car "starts" but doesn't run, it means the starter motor is working and cranking the engine, but the engine isn't igniting and running.
Possible Causes
1. Fuel System Issues:
- Empty Tank: This is the most basic check.
- Fuel Pump Failure: The fuel pump delivers gas to the engine. If it's not working, no fuel will reach the cylinders.
- Clogged Fuel Filter: A dirty fuel filter can restrict fuel flow.
- Bad Fuel: Old or contaminated fuel can prevent the engine from running smoothly.
- Fuel Line Problems: Cracks or leaks in fuel lines can disrupt fuel delivery.
2. Ignition System Issues:
- Spark Plug Problems: Worn, fouled, or improperly gapped spark plugs can prevent the spark needed to ignite the fuel.
- Spark Plug Wires: Damaged or loose spark plug wires can disrupt the electrical signal to the spark plugs.
- Ignition Coil Failure: The ignition coil provides the high voltage needed for the spark plugs.
- Distributor Issues: In older cars, a faulty distributor can disrupt the spark timing.
- Bad Ignition Switch: This switch sends electrical signals to the ignition system.
3. Air Intake Issues:
- Air Filter Clogged: A dirty air filter can restrict airflow, making it hard for the engine to run.
- Intake Manifold Leak: A leak in the intake manifold can cause air to enter the engine at an incorrect rate.
4. Compression Issues:
- Low Compression: Worn piston rings or damaged valves can lead to low compression, preventing the engine from running.
Troubleshooting Steps
1. Check Fuel: Make sure the gas tank isn't empty.
2. Listen for the Fuel Pump: Turn the key to the "on" position (not start) and listen for the fuel pump whirring. If you don't hear it, it might be faulty.
3. Check Spark: Remove a spark plug wire and hold it near a metal part of the engine while someone cranks the engine. Look for a spark jumping across the gap. If there's no spark, check the spark plugs, wires, ignition coil, and distributor (if applicable).
4. Inspect Air Filter: Remove the air filter and check if it's dirty.
5. Check for Intake Leaks: Look for any visible cracks or leaks in the intake manifold.
Additional Tips
* Check Engine Codes: If your car has a check engine light, get the codes read to diagnose possible problems.
* Consult a Mechanic: If you're not comfortable troubleshooting the problem yourself, consult a qualified mechanic.
Important Note: Always be cautious when working with car parts, especially electrical components. Disconnect the battery before working on the ignition system.
