Possible Causes:
1. Fuel Delivery Issues:
* Fuel Pump Relay: The fuel pump relay is a small electrical component that activates the fuel pump. It might be faulty, preventing the pump from receiving power.
* Fuel Pump Fuse: Check the fuse for the fuel pump. A blown fuse will also prevent the fuel pump from working.
* Fuel Pump Itself: Although you mentioned the fuel pump is "good," it's possible it's failing intermittently or has a weak output.
* Fuel Filter: A clogged fuel filter can restrict fuel flow and prevent the engine from receiving enough fuel to start.
2. Spark Issues (Even Though You Have Spark):
* Spark Timing: While you mentioned spark plugs are firing, check for proper spark timing. Incorrect timing can prevent proper combustion.
* Spark Plug Wires: Worn or damaged spark plug wires can cause misfires or weak sparks.
3. Air Intake Issues:
* Air Filter: A very clogged air filter can restrict air flow and prevent the engine from starting.
* Intake Manifold Leaks: A leak in the intake manifold will introduce unmetered air into the engine, disrupting the air/fuel mixture and preventing starting.
Troubleshooting Steps:
1. Verify Fuel Pump Operation:
* Listen for the fuel pump: Turn the key to the "ON" position (not start) and listen carefully for the fuel pump to hum.
* Check Fuel Pressure: If you have a fuel pressure gauge, connect it to the fuel rail and check the pressure.
* Test the Fuel Pump Relay: With the key off, locate the fuel pump relay (consult your owner's manual or a repair guide). Swap it with another relay of the same type (if possible) to see if it resolves the issue.
2. Inspect Air Intake:
* Check the Air Filter: Inspect the air filter for dirt and debris. Replace it if necessary.
* Look for Intake Leaks: Visually inspect the intake manifold and hoses for cracks, leaks, or loose connections.
3. Recheck Spark Timing (If Applicable):
* Consult Your Owner's Manual: This will provide specific instructions for your vehicle.
* Seek Professional Help: If you're not comfortable with timing adjustments, take it to a mechanic.
Additional Tips:
* Visual Inspection: Look for any loose wires, disconnected hoses, or other obvious problems.
* Diagnostic Codes: A mechanic can use a code reader to check for any fault codes stored in the engine control unit.
* Fuel System Cleaner: If you suspect a fuel delivery issue, you could try adding a fuel system cleaner to your tank.
* Starter Motor: Although you mentioned cranking, ensure the starter motor is healthy. A weak starter could prevent the engine from turning over fast enough to start.
Important Note: If you're not comfortable working on your vehicle, it's best to seek professional help from a qualified mechanic. This will help you diagnose the problem correctly and ensure a safe repair.
