1. Verify the New Fuel Pump Installation:
* Power to the Pump: The most common mistake is a faulty connection. Double-check all electrical connections at the pump itself and the fuel pump relay. Ensure the wires are securely attached and not damaged. A multimeter can verify power is reaching the pump when the ignition is switched on.
* Ground Connection: A poor ground connection can prevent the pump from functioning. Inspect the ground wire for corrosion or looseness.
* Fuel Pump Relay: Test the fuel pump relay. You can often swap it with another relay of the same amperage (check your owner's manual or online forums) to see if the problem lies there. A bad relay is a frequent culprit.
* Fuel Pump Fuse: Check the fuel pump fuse (consult your owner's manual). A blown fuse will prevent power from reaching the pump.
* Pressure Check: This is crucial. You'll need a fuel pressure gauge to measure the pressure at the fuel rail. The pressure should be within the specifications listed in your owner's manual (usually around 40-50 PSI, but check yours). Low or no pressure indicates a problem even with a new pump.
* Correct Pump Installation: Did you install the pump correctly? Was the fuel pump sock (filter) properly installed and free of debris? A damaged sock can restrict fuel flow.
2. Beyond the Fuel Pump:
If the fuel pressure is good, the problem lies elsewhere:
* Crank Sensor: A faulty crankshaft position sensor prevents the engine from knowing when to fire the spark plugs.
* Cam Sensor: Similar to the crank sensor, a malfunctioning camshaft position sensor will stop the engine from starting.
* Ignition System: Check spark plugs, wires, distributor cap (if applicable), and ignition coil for damage or wear. A weak spark won't ignite the fuel.
* Fuel Injectors: While less likely, clogged or faulty fuel injectors can prevent fuel from reaching the cylinders. This requires more specialized testing.
* Security System: Does your car have a factory or aftermarket security system that might be disabling the engine?
* Computer/ECM: In rare cases, a faulty engine control module (ECM) could be at fault. This requires diagnostic scanning by a mechanic.
Troubleshooting Steps:
1. Start with the easy checks: Fuses, relays, and visual inspection of wires.
2. Fuel pressure test: This is critical to rule out fuel delivery issues.
3. Ignition system check: Spark and coil testing.
4. Sensors: Test the crank and cam sensors if the above checks don't reveal the issue.
5. Professional help: If you're not comfortable with these tests, take your Cavalier to a qualified mechanic. They have the tools and expertise to diagnose the problem efficiently.
Don't just jump to conclusions. Systematic troubleshooting will help you pinpoint the cause of the starting problem, even after replacing the fuel pump. Remember safety first; disconnect the negative battery terminal before working on any electrical components.
