1. Fuel System Issues:
* Empty Tank: Sounds obvious, but double-check the fuel gauge and consider adding a gallon of gas to rule this out.
* Fuel Pump: A weak or failing fuel pump may not deliver enough fuel to the engine. You might hear a weak whirring sound from the fuel pump when you turn the key to the "on" position (but *before* cranking). Lack of this sound is a strong indicator of a fuel pump problem.
* Fuel Filter: A clogged fuel filter restricts fuel flow. This is a relatively inexpensive part to replace.
* Fuel Injectors: Faulty injectors might not be spraying fuel properly. This is harder to diagnose without specialized tools.
* Fuel Pressure Regulator: A malfunctioning regulator could cause low fuel pressure.
2. Ignition System Problems:
* Spark Plugs & Wires: Worn, fouled, or damaged spark plugs or wires prevent proper ignition. Check for cracks or corrosion. These are relatively easy and inexpensive to replace.
* Ignition Coil(s): A faulty ignition coil(s) won't deliver the necessary spark to the plugs. This requires testing with a multimeter or specialized tool.
* Crankshaft Position Sensor (CKP) or Cam Position Sensor (CMP): These sensors tell the computer the engine's rotational position, crucial for timing the spark. A faulty sensor prevents the engine from firing. These require testing with a multimeter or diagnostic scanner.
3. Other Possibilities:
* Battery: While it cranks, a weak battery might not provide enough power to the ignition system. Check the battery voltage.
* Alternator: While related to the battery, a bad alternator won't charge the battery, eventually leading to starting problems.
* Security System: If the car has an aftermarket or factory alarm/immobilizer system, a malfunction might be preventing the engine from starting. Check the car's owner's manual for troubleshooting the security system.
* Computer/ECU Problems: A faulty engine control unit (ECU) could be preventing fuel delivery or ignition. This is the least likely but most difficult to diagnose without specialized tools and knowledge.
Troubleshooting Steps:
1. Check the obvious: Fuel level, obvious damage to wiring or components.
2. Listen carefully while cranking: Do you hear any unusual noises (clicking, whirring, grinding)?
3. Check for error codes: Use an OBD-II scanner to read any diagnostic trouble codes (DTCs) stored by the car's computer. This can significantly narrow down the possibilities.
4. Visual Inspection: Look for any obvious signs of damage, corrosion, or loose connections in the engine bay, particularly around the fuel system and ignition components.
5. Basic Tests: Check the spark plugs for spark (carefully!), and test the battery voltage.
Recommendation:
If you're not comfortable performing these checks yourself, taking the car to a qualified mechanic is the best option. They have the tools and expertise to diagnose the problem accurately and efficiently. Providing them with the information you've gathered from your own checks will help them diagnose the problem more quickly.
