* Fuel Delivery Issues (Beyond the Pump and Filter): While you've replaced the fuel pump and filter, there could still be problems:
* Clogged Fuel Injector(s): Fuel injectors can become clogged, preventing fuel from reaching the engine. A fuel injector cleaner might help, but a professional inspection/cleaning or replacement might be necessary.
* Fuel Pressure Regulator: This component regulates fuel pressure in the system. A faulty regulator could lead to insufficient fuel pressure even with a good pump.
* Fuel Pump Relay (even if checked): Sometimes relays can be intermittent. Double-check its functionality and connections.
* Bad Fuel Pressure Sensor: Incorrect readings from this sensor can prevent the car from starting.
* Ignition System Problems: Even with new plugs and wires:
* Distributor Issues (if applicable): A 1997 Malibu might have a distributor; if so, the cap, rotor, or even the distributor itself could be faulty.
* Ignition Coil: The coil provides the high voltage needed for spark. A weak or faulty coil won't provide enough spark to ignite the fuel.
* Crankshaft Position Sensor (CKP) or Cam Position Sensor (CMP): These sensors tell the computer the engine's position to time the spark correctly. A faulty sensor will prevent starting.
* Computer/Electrical Problems:
* PCM (Powertrain Control Module) Issues: The car's computer might have a problem preventing it from sending the signals needed to start. This is less likely but possible.
* Security System Issues: If it has a factory alarm or immobilizer, a malfunction could prevent starting.
* Air Intake System:
* MAF (Mass Airflow Sensor): A dirty or faulty MAF sensor can prevent the engine from getting the correct air/fuel mixture.
Troubleshooting Steps:
1. Check for Spark: Use a spark tester or a spare spark plug to see if you're getting spark at the plug wires. This will quickly tell you if the problem is ignition-related.
2. Check Fuel Pressure: You'll need a fuel pressure gauge to measure the fuel pressure at the fuel rail. This will determine if the fuel pump is actually delivering sufficient pressure.
3. Scan for Codes: Use an OBD-II scanner to check for any diagnostic trouble codes (DTCs) stored in the car's computer. These codes can pinpoint potential problems.
4. Visual Inspection: Carefully inspect all wiring connections, looking for anything loose, corroded, or damaged.
If you're not comfortable performing these checks yourself, take it to a mechanic for diagnosis. Providing the mechanic with the information that you've already replaced several components will help them narrow down the possibilities.
