1. Fuel System Issues:
* Empty or low fuel: Sounds obvious, but worth checking first!
* Fuel pump failure: The fuel pump delivers fuel to the engine. A faulty pump won't supply enough fuel for ignition. You might hear a whirring sound from the fuel pump when you turn the key if it's struggling.
* Clogged fuel filter: A clogged filter restricts fuel flow.
* Fuel pressure regulator problems: This regulates fuel pressure; a malfunction can lead to insufficient fuel delivery.
* Bad fuel injectors: These spray fuel into the cylinders. Clogged or faulty injectors prevent proper fuel delivery.
2. Ignition System Problems:
* Dead battery: Even if the engine cranks, a weak battery might not provide enough power for ignition. Check the battery voltage with a multimeter.
* Faulty ignition coil: This delivers high voltage to the spark plugs. A cracked or failing coil won't create a spark.
* Spark plug problems: Worn, fouled, or damaged spark plugs prevent proper ignition.
* Ignition control module (ICM): This controls the ignition timing; a failure can prevent the engine from starting.
* Crankshaft position sensor (CKP): This sensor tells the computer where the engine is in its cycle. A faulty sensor prevents proper ignition timing.
* Camshaft position sensor (CMP): Similar to the CKP, but for the camshaft. A faulty sensor will disrupt the timing.
3. Other Potential Issues:
* Security system issues: Some anti-theft systems can prevent starting if the key isn't recognized correctly.
* Faulty starter: While the engine cranks, a weak starter might not be providing enough power to consistently start the engine. This is less likely if the cranking is strong.
* Low compression: If the engine's compression is low (due to worn rings, valves, or head gasket issues), it might crank but not fire. This is usually accompanied by other symptoms, like unusual engine noises or smoke.
Troubleshooting Steps:
1. Check the obvious: Fuel level, battery voltage (use a multimeter), and any error codes (check the engine light using an OBD-II scanner).
2. Listen carefully: Pay attention to unusual noises during cranking (e.g., clicking, whirring).
3. Check spark: With the spark plugs removed, have someone crank the engine while you observe if you see a spark jumping across the gap of each spark plug. (Be careful – high voltage!).
4. Inspect the fuses and relays: Check the fuses and relays related to the fuel pump and ignition system.
Important Note: If you're not comfortable working on your car, take it to a qualified mechanic. Improperly diagnosing or repairing these issues could lead to further damage or injury. An OBD-II code reader can help pinpoint potential problems more easily.
