* Fuel pump: The fuel pump might be weak or failing, unable to deliver sufficient fuel pressure even with a new filter. A clogged fuel pump sock (located inside the tank) is also a possibility.
* Ignition system problems: While you've replaced plugs and wires, the problem could lie elsewhere in the ignition system:
* Ignition coil: A failing coil won't provide the necessary high voltage to the spark plugs.
* Distributor cap and rotor (if equipped): Cracks or corrosion in the distributor cap or worn rotor can prevent a strong spark. These are common points of failure in older vehicles.
* Ignition control module (or ECU): This electronic component controls the ignition timing and spark. A faulty module can lead to starting issues.
* Cranking speed: The starter motor might be weak, not turning the engine over fast enough to generate sufficient spark for combustion.
* Battery and charging system: A weak battery or alternator won't provide enough power for starting. Test the battery voltage and have the alternator checked.
* Sensor issues: Various sensors (crankshaft position sensor, camshaft position sensor, etc.) tell the engine's computer how to time the ignition and fuel injection. A faulty sensor can prevent starting.
* Fuel delivery issues: Even with a new filter, there might be a blockage further down the line in the fuel system, such as a clogged fuel injector.
* Timing belt/chain: If the timing is off (belt/chain broken or slipped), the engine won't start. This is a more serious issue.
* Low compression: Worn piston rings or valve problems can lead to low compression, making starting difficult.
* Flooded engine: Too much fuel in the cylinders can prevent starting.
Troubleshooting Steps:
1. Check for spark: Make sure you have a strong spark at the spark plugs. A simple spark tester can confirm this.
2. Check fuel pressure: This requires a fuel pressure gauge and is a more involved process, but it's crucial to verify fuel is reaching the injectors.
3. Battery voltage test: Check the battery voltage with a multimeter.
4. Starter motor test: Listen carefully to the starter motor. Does it crank the engine over strongly?
5. Have the vehicle scanned for diagnostic trouble codes (DTCs): A code reader plugged into the vehicle's diagnostic port can provide clues about the problem.
Because several systems are involved in starting a car, tackling this requires systematic checking, rather than just replacing parts hoping for the best. If you're not comfortable working on cars, it's best to take it to a mechanic for diagnosis.
