I'll start from the beginning, truck stall shortly after starting. Drove home from work and it died in the driveway, I took the tuner off of it and no luck, replaced fca, rail pressure sensor, pressure relief valve on the rail and on the cp3 as well. Only code that was showing was p0088 high rail pressure, took it to the dearer and tech thought the fca was faulty, the new one so I put a new one on and it did not help. He also said that 2 injectors are showing around 120% on the test. Took it to cummins and they told me that number 3 and 4 injector were bad so I replaced the both fired her up and still the same fuel knock, I did clear the codes and no p0088 anymore but truck falls on her face and knocks bad, cummins said the unplugged each injector and the knock went away when they disc. The 3 4 injectors. Tech thought bad nozzles. I did notice something when I installed the injectors, the retain bolts that hold the injectors down appeared to be loose on the side that the covered by the rocker. I feel like a a$$#+%! For not thinking to just pull the rest of the rockers and check the remaining injectors. I will do that. There is no fuel in the oil and no blow by fuel filter changed and new lift pump as well..
Thanks in advance for ur help.

 

I think i would find a qualified shop. I vote that you've got a bad injector yet, did they perform a return flow test and measure each injector by blocking off an injector at a time with a fuel block off? I would also consider switching them around and seeing if the knock moves! Actually it would probably be my first move at this point.

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I just had a simmilar problem on my 03 and I just retightnen the injector tubes and now the truck runs like it was new, on injector tube was loose.

 

So, as of today I have replasced the :
fuel rail pressure sensor, fuel filter, oil, 2 fuel feed tubes, all 6 injectors, prv on rail and the CP3, FCA 3 times, lift pump, fca pigtail.

So here goes it: I picked up new fca from cummins, intalled and truck ran great, took it home 16 miles and drove back to work 16 miles. On the way to work I got CEL and fuel knock, as I expected P0088, and P0251, I reset and drove with no problems for 1/4 mile, same thing, brought it back and wiggled wiring, no change, pulled fuel rail pressure sensor connector off and got with key on 5v #1 5v#2 and 0 #3, checked fca connector, 5v form one and 0 from other, I was unsure of if I may have messed up the wiring on the FCA when I put the pigtail on, so if you may know the correct wiring for the FCA plugged into the pump which wire is which it may be a help. Anyway, I got truck running again with no CEL, but will stall after starting in 3-5 seconds, I hear what sounds like high fuel rail pressure with the knock, but no codes!!!

I really need help!

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BTW, I do not have a pressure guage, but I will try to get one.....Here is a question, if CP3 is failing, would the cp3 actually max out rail pressure or is the ECM just callng for it and not getting it. Asking to see if maybe CP3bad, but Im tired of replacing parts, u guys are the best, have helped in the past........

 

Ive got a used rail pressure gauve from quad if you need one.

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