* Fuel Injectors: Even with a new fuel pump, the injectors could be clogged, faulty, or not receiving the correct signal from the engine control module (ECM). This is a common problem on fuel-injected vehicles.
* Fuel Pressure Regulator: This component regulates the fuel pressure going to the injectors. A faulty regulator can prevent sufficient fuel from reaching the injectors.
* Crankshaft Position Sensor (CKP) or Cam Position Sensor (CMP): These sensors tell the ECM the position of the crankshaft and camshaft, which is critical for ignition timing and fuel injection. A faulty sensor will prevent the engine from starting.
* Ignition Control Module (ICM): The ICM controls the ignition system. A failed ICM will prevent spark. While you replaced the plugs and wires, the ICM itself could be the culprit.
* Engine Control Module (ECM): The ECM is the "brain" of the fuel injection system. A faulty ECM can prevent the engine from starting due to improper fuel delivery and ignition signals. This is less likely, but possible.
* Distributor (if applicable): While less common in some 3.1L configurations, a faulty distributor can prevent proper spark distribution. Ensure the distributor cap and rotor are correctly aligned and functioning.
* Battery/Wiring: Even with a new starter, a weak battery or corroded/loose connections can prevent sufficient current from reaching the starter or other components.
* Security System (if equipped): Some 1991 Camaros may have had factory or aftermarket anti-theft systems. A problem with the security system could prevent the car from starting.
* Clogged Fuel Filter: While less likely after replacing the fuel pump, a clogged fuel filter can restrict fuel flow to the injectors.
Troubleshooting Steps:
1. Check for Spark: Use an inline spark tester on a spark plug wire to see if you have a strong spark at each cylinder.
2. Check Fuel Pressure: Use a fuel pressure gauge to measure the fuel pressure at the fuel rail. Consult your owner's manual or a repair manual for the correct specifications.
3. Check for Fuel Injector Pulse: Use a test light or multimeter to check if the fuel injectors are receiving a signal from the ECM.
4. Scan for Diagnostic Trouble Codes (DTCs): If possible, use an OBD-I scanner to check for any diagnostic trouble codes stored in the ECM. This can pinpoint the source of the problem.
It's highly recommended to consult a repair manual specific to your 1991 Chevy Camaro 3.1L. This will give you diagrams, specifications, and troubleshooting steps for your specific vehicle. Ignoring the fact that this is a fuel-injected engine is a major mistake in your troubleshooting; the lack of a carburetor dramatically changes the diagnostic process.
