2007 Chevrolet Silverado 5.3L V8 Misfire and No Start Issues
I have a 2007 Chevrolet Silverado with a 5.3l V8. Started misfiring while driving down the highway. No start condition after turning off. Occasionally it will start but very rough idle with misfires. Initially had a P0320 code. Also noted misfires in 2,3 and 7. Replaced the camshaft and crankshaft position sensors. I also moved ignition coils around from cylinders not misfiring. No improvement. Now have a P0230, P0300, and P0106. Same condition. I tested the fuel pump relay with a OBD device and could hear the fuel pump acitvate. I know the fuel pump has been replaced within the last 2 years. I am not too familiar with fuel issues and diagnosing them. I wouldn’t think injectors would go bad in 3 cylinders at once. Maybe fuel delivery. To me it’s weird why that combination of cylinders would misfire. I am spiraling and think maybe I have a bad lifter failure but I wanted to try and rule everything else out first.
Most likely, you’ve got a fuel delivery problem—either the fuel pump isn’t supplying pressure, or there’s a power/control issue to the pump. The P0230 code points to a fuel pump primary circuit fault, which fits with your no-start and rough running. The random misfires (P0300) and MAP sensor code (P0106) are likely side effects of low/no fuel pressure. Lifter failure is possible, but not the first thing I’d chase with these codes and symptoms.
Most likely culprits
- Fuel pump not running or weak — Common on these trucks, even with a newer pump. P0230 means the PCM isn’t seeing the pump circuit working right.
- Fuel pump relay or fuse issue — Cheap and easy to check, and can cause intermittent or no fuel delivery.
- Wiring to fuel pump — Corrosion or broken wires at the frame rail or pump connector, especially if the pump was replaced recently.
How to narrow it down
- Spray starting fluid into the intake and try to start. If it fires up briefly, you’re definitely lacking fuel.
- Check fuel pressure at the rail (Schrader valve on driver side fuel rail). Key on, engine off: should see 55-62 psi. If zero or way low, pump isn’t working right.
- Listen for the pump: Key on, you should hear the pump prime for 2 seconds. No sound = pump, relay, fuse, or wiring.
- Swap the fuel pump relay with another identical relay in the fuse box. If it starts, relay was bad.
- Check the fuel pump fuse (labeled "FUEL PMP" in underhood box). Make sure it’s not blown or corroded.
- Inspect wiring at the pump (above the tank, driver’s side frame rail). Look for green/white corrosion, loose pins, or broken wires.
- If all above checks out, test for power and ground at the pump connector while cranking. No power = wiring or PCM issue.
Possible parts (if needed)
- Fuel pump (if no/low pressure at rail and power/ground are good)
- Fuel pump relay (if swapping fixes it)
- Fuel pump fuse (if blown or corroded)
- ECM (only if all wiring and power checks out and still no pump control)
A few questions
- When you cycle the key to ON (not start), do you hear the fuel pump prime for 2 seconds every time?
- Have you checked actual fuel pressure at the rail with a gauge, or just listened for the pump?
- Was the fuel pump replaced with an OEM/Delphi/ACDelco unit, or a cheaper aftermarket one?
Let’s rule out fuel delivery first before chasing lifters or internal engine problems. If you get fuel pressure and it still misfires, then we dig deeper.