About 6 months ago I changed plugs, wires, cap, and rotor with all AC Delco parts. About 2 months after that I had to put the truck in the shop because I was having fuel issues. They changed the fuel pressure regulator and the #5 fuel injector. A year before that I changed the fuel pump. My question is being I changed the electrical parts while still running bad, before the fuel parts were changed, could I have fouled the plugs? Today is Mardi Gras here in New Orleans so I have to wait till tomorrow to get it to a parts store and check the computer. Just looking for yalls opinions. It's an 01 LT Blazer 4X4.

 

These are my codes: P0175, P0172, P0335, and P0456.

 

P0175 & P0172 are indicating a rich fuel mixture on both banks. Check fuel pressure and leakdown first. Key ON, engine OFF, fuel pump running: Pressure must be 60psi to 66psi. It must remain above 55psi for at least 10 minutes after the pump shuts off. Post your results and we can continue.

 

Could the crankshaft position sensor code be the cause of the other codes? I'm going to replace the sensor tomorrow.

 

Always diagnose and repair DTC's in the order they are retrieved. The first one can set others, and they might not be accurate. DON'T replace the crankshaft position sensor until the rich DTC's are diagnosed & repaired, all memories are cleared, and a General Motors Driving Cycle is performed to confirm the repair. If more DTC's show up during or after the drive cycle, diagnose, repair, clear memories, and do another drive cycle.

FYI: After replacing the crankshaft position sensor, the crankshaft position sensor relearn MUST be done using a capable scan tool, (the el cheapo $500 jobbies can't initiate it).