* Fuel Delivery Issues (despite new pumps and filter):
* Clogged fuel line: A blockage somewhere *between* the tank and the engine could still prevent fuel from reaching the injectors. Inspect the lines for kinks, damage, or debris.
* Fuel pressure regulator: This component might be faulty, not maintaining the correct fuel pressure even with new pumps.
* Fuel injectors: They could be clogged or faulty, preventing fuel injection into the cylinders. This often requires specialized tools and testing to diagnose.
* Incorrect fuel type: Make absolutely sure you're using the correct type of fuel for your truck's engine.
* Ignition System Issues (despite confirming spark):
* Weak spark: While you've confirmed *some* spark, it might be too weak to reliably ignite the fuel-air mixture. Check the spark plug wires and coil for damage or wear. A coil test might be necessary.
* Timing: The ignition timing could be significantly off, meaning the spark occurs at the wrong moment in the engine cycle. This usually requires specialized tools to check.
* Crankshaft Position Sensor (CKP) or Cam Position Sensor (CMP): These sensors tell the engine's computer when to fire the spark plugs. A faulty sensor will prevent starting.
* Other Potential Issues:
* Low compression: If the engine's cylinders don't have sufficient compression, the fuel-air mixture won't ignite effectively even with spark and fuel. A compression test is needed to diagnose this.
* Security system: The truck's anti-theft system might be preventing it from starting. Check your key fob and any associated immobilizer systems.
* Battery: While seemingly unrelated, a weak battery might not provide enough power for the starter motor to crank the engine sufficiently, even if the ignition system is working.
Troubleshooting Steps:
1. Verify fuel pressure: Use a fuel pressure gauge to measure the pressure at the fuel rail. This will tell you if the fuel pumps are actually delivering sufficient fuel.
2. Check for fuel at the injectors: Listen for the injectors clicking when you crank the engine. If not, there might be an electrical problem with the injectors or the fuel pump relay.
3. Inspect the spark plugs: Check for a strong, consistent blue spark at each plug while cranking the engine.
4. Test the crankshaft and camshaft position sensors (if equipped): This usually involves using a scan tool to check sensor readings.
5. Perform a compression test: This will reveal whether the engine has sufficient compression in each cylinder.
It's highly recommended to consult a qualified mechanic if you're not comfortable performing these diagnostics and repairs yourself. They have the tools and expertise to quickly pinpoint the problem.
