jbarry14

I am starting to think it is the intake gaskets. I am not sure if they have ever been done, but the smoke test I am going to do tonight should give me a definitive answer. I was just hoping there might be a sensor or something besides a vacuum leak that I could check in the meantime that would only effect bank 2.

There are no miss fires. Compression is good I will be smoke testing the engine later tonight The parts that I have replaced, had to be replaced. The fuel pump was only putting out max 45 key on engine off, way under spec. The check valve in the pump was also bad and making the pressure drop to 0 instantly after the pump would shut off. Since I replaced the pump, I wanted to do the fuel filter at the same time. Now I have spec fuel pressure and it holds after the pump shuts off. I had codes for 2 bad O2 sensors, The others didn't throw a code, but they could still be giving off bad readings and they were cheap enough that I wanted to just do them all. Now the only code I have is for bank 2 being lean.

I just wanted to give an update. I had the fuel pump replaced on my truck. That helped with some of the problems. But now I am getting a lean code for bank 2 only. I had a shop put a camera down the intake to look at the FPR and Injectors. The previous owner had the FPR and Injectors replaced with the new style and they are all working perfectly. All of the O2 sensors have been replaced very recently as well. My LTFT on bank 2 is at 25%. What else can I look for or test to figure out why the only code I get is for bank 2 being lean? It seems to run a little more rough when the air temperature warms up. It has been very cold here in Minnesota recently.

I will check the oil. The FPR could still be bad, but the pressure is not to spec either. The other thing is that when the pump shuts off, the pressure immediately drops to 0. If the FPR is bad, wouldn't it take longer for the pressure to go down? I am thinking the pump is bad and the check valve in the pump is bad and the fuel is going right back to the tank.

96 Chevy K3500 with the 5.7l It has about 215K miles. I am trying to diagnose a fuel pressure issue. My truck first started to run rough like it had a miss. Check engine light came on. I had codes for both banks being lean. I cleaned the MAF sensor with no change. I checked for vacuum leaks. I hooked up a scan tool and checked the LTFT for both banks. They are both at 25%. I hooked up a fuel pressure gauge to the rail test port. Key on engine off it is around 45. As soon as the pump shuts off it almost instantly drops to 0. I am trying to figure out if I have a bad check valve in my fuel pump or if my FPR is bad. Before this all started, I noticed a loss in power. It could barely get a trailer up the slightest incline. I was trying to see if I could find out the difference in the speed of fuel pressure dropping when the check valve in the pump is bad and when the FPR is bad, to try and isolate the issue.