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low rail pressure

1648 Views 13 Replies 3 Participants Last post by  rs002
i got an 03 with a new motor, injectors, and airdog fuel system. the past two days the truck has been low in power and yesturday it started dyin bouyt evert 15 seconds. i put an edge insight on it and it has low rail pressure. i drove it today and was doin good then the same thang, rail pressure dropped to 2k then died. start it back it would run bout 10 secs and die. got it to oriely changed the fuel filter when i left it would build 11k pressure just pullin outa the driveway it didnt take long for the pressure to start dropping and after about 6 miles it wouldnt build over 5k even at WOT. no codes are present. any ideas would be apreciated.
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need to know the pressure from the airdog at the cp3. if we assume (if you assume you make an a$$ out or u and me) you are getting fuel to the cp3, than the cp3 is most likely dead. how many miles on the cp3?
whats your RP at when cranking to start. when it dies you could try unplugging the fca and starting. RP should hit in the 26k psi range(if i remember correctly). DO NOT drive it like this,
15k psi with fca unplugged either means bad fca or bad pump. is there anyone you know that you can swap fca's with to see if it solves your problem?

re-read post. 5k psi at idle is too low. do a search and check your pressure relief valve to rule that out but i have never seen a leaky valve kill the motor, just lower RP. its sounds like a bad pump.

no white smoke on start up? is your truck "making" oil?
stealerships are terrible and will cost you alot$$$ is there not a diesel shop around you. i dont want to suggest what you should replace and waste your money but if i was you i would NOT go to the dealership and if your pockets are that deep just go buy a new cp3. if you are confident its not your injectors(do a search on the tell tale signs). i would buy a cp3.......if you are willing to possibly throw away money. i dont know if it was said...any codes?
thats what i think(cp3). the dealership might not be too expensive if you tell them whats going on and want them to check the pump. fuel injector return flow rate is what you want to check. search for it, i cant remember what to do. i think there is a way to check it without a scan tool. if it was my truck i would replace the pump. although i want a pump from shane anyways so either way its not a waste of money. im not telling you what to do, i dont want you to possibly throw away money. bad injector(s) shouldnt cause a problem this bad without the tell tale signs of white smoke, raw diesel smell ect. if crappy injectors were causing the very low RP when your on the throttle you would smell the diesel and probably have a hole in a piston

if you have any future plans on mods like bigger injectors, aggressive tuning etc... get a motorsport pump from shane and dont worry about it ever again. if no mods in the future get a NEW pump, no re-man
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