1. Fuel System:
* Empty Tank? Sounds obvious, but check the fuel gauge.
* Fuel Pump: Listen carefully near the fuel tank while someone cranks the engine. You should hear a brief humming sound from the fuel pump when the key is first turned to the "on" position (before cranking). If you don't hear it, the pump might be faulty or the fuel pump relay could be bad.
* Fuel Filter: A clogged fuel filter can restrict fuel flow. This is less likely to be the sole cause, but it's a possibility.
* Fuel Pressure: This requires a fuel pressure gauge to check the pressure at the fuel rail. A low pressure reading indicates a problem within the fuel system.
2. Ignition System:
* Spark Plugs and Wires: Check the spark plugs for fouling (black, wet, or oily). Inspect the spark plug wires for cracks or damage. A simple test is to remove a plug, attach it to the wire, ground it to the engine block, and have someone crank the engine. You should see a strong spark. If not, you have a problem in the ignition system.
* Ignition Coil: If you don't see a spark at the spark plugs, the ignition coil is a suspect.
* Distributor (if applicable): Older cars with distributors need to have the rotor and cap checked for wear or damage. The Sunfire likely uses a coil-on-plug system, so this is less likely to be an issue.
* Crank Position Sensor (CKP): This sensor tells the computer the position of the crankshaft. A faulty CKP sensor will prevent the engine from getting the spark it needs.
3. Air Intake System:
* Air Filter: A severely clogged air filter can restrict airflow to the point where the engine won't start.
4. Security System:
* Immobilizer System: Some Sunfires have an immobilizer system that prevents the engine from starting if the correct key isn't used. Try a different key if you have one. If the alarm is triggered during attempts to start the car, there might be a problem with the system.
5. Battery and Starting System:
* Battery Voltage: Test the battery voltage with a multimeter. It should be around 12.6 volts when not cranking and above 10 volts while cranking. A weak battery can prevent starting.
* Battery Cables: Check the battery terminals and cables for corrosion or loose connections. Clean them if necessary.
* Starter Motor: While you say the engine cranks, a weak starter might not be providing sufficient power. If the cranking is very slow, the starter could be failing.
Troubleshooting Steps:
1. Start with the easiest checks: Fuel level, air filter, battery voltage, and terminal connections.
2. Listen for the fuel pump: This is a quick way to eliminate a fuel delivery issue.
3. Check spark: This is crucial for eliminating ignition problems.
4. Consider professional help: If you're not comfortable performing these checks or if the problem persists, take your Sunfire to a qualified mechanic. They have the tools and expertise to diagnose the issue accurately.
Remember safety first! Disconnect the negative battery terminal before working on any electrical components. Never work under a car without proper jack stands.
