Hi everyone. I’m a little stumped and need some help. I have a 2001 GMC Sierra hd with the lb7. I rebuilt four of the injectors on the passenger side and replaced the fuel filter. The truck ran before I messed with it and the reason I rebuilt the injectors is because I had a white haze at idle. I had high out of spec balance rates on cylinders 3 and 5. When I had them apart the ball and seats looked perfect. I replaced the prongs and nozzles. When I got it back together it would not start. My first thought was what did I screw up so I did a return test and that came back well within spec. With the tech 2 the actual rail pressure only reaches around 700psi. I was thinking that maybe I have air in the supply side and the pump has air cavitating which would not allow for pressure to build. I replaced all of the supply rubber hoses and no change. It cannot be injectors or the pressure relief valve since the return test came back normal. I did try unplugging the fpr to see if that would force higher rail pressers but no change. The results seem to point to the cp3 being bad but I really struggle with that since it worked before all of this. Seems unlikely that it could just go bad. There are no internal or external fuel leaks. The engine oil level remains constant. This engine does have 340,000 miles on it. Cp3 has been replaced before but not sure at what mileage. Injectors were replace as part of the recall long before I owned this truck. If anyone has any insight it would be greatly appreciated
2001 lb7 cranks but won’t start
- Thread starter Themm84
- Start date
If it ran before you touched the injectors I would say you did something wrong. Putting new nozzles is NOT the fix. Replace the injectors with genuine Bosch. Even the best injector builders in the country still only start with a genuine Bosch reman or new for a reason.
