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New CP3 installed now surges at idle

10K views 18 replies 11 participants last post by  kgbarnett22 
#1 ·
Like the title says I installed a new CP3 from Pensacola Diesel because my old one was getting weak and limping and throwing codes while towing. The truck did not surge at idle with the old CP3. It surges the worst when in gear with the brake holding the vehicle stopped. It will also surge in park when the heater/AC compressor engages. I bought it with a PPE barbed fuel inlet fitting, but have replaced that one with the stock one hoping that would fix the problem. I am thinking next I will put the fprv from the old CP3 back in and try that. If anybody has any other ideas I would love to hear them. Garlen
 
#2 ·
Mine surges everynow and then when stopped and with the a/c in park, except im still with the original Cp3. Dirty filter maybe? Just throwin out ideas.
 
#4 ·
Was it an all original LB7 pump and regulator that was ordered from PD? Did you buy a pump with a modified regulator?

Most often, surge at idle points at a fuel pressure regulator. If the pump and regulator are from a newer version, like that out of an LBZ, the rail pressure will have to be rescaled to get the surge out with the new regulator.
 
#8 ·
I will try the old fpr and if that works I will get them to send me a new one. They were the ones that told me to take the PPE nipple out and put the stock one in.
 
#12 ·
First things first, is the new FPR connector straight or at a 90? If it is straight then it is an LB7, if it is at a 90 then it is either an LLY(which will work) or an LBZ. the LBZ regulator needs to have the fuel rail valve current re-scaled in order to work in an LB7 or early style lLY as the regulator is completely different internally. If the connector is in fact staright, then you most likely have a bad FPR. I know I would never run another set of PD's injectors, and from the sounds of it it doesn't sound like I would want to run ther CP3 either.
 
#14 ·
I dont mean to hijack the thread but my question is related. Im curious about the FCA on the LB7 CP3. You stated it was straight and the others were 90 degree. I have changed, swapped and replaced the LBZ/LLY style and the FCA in the Cummins, but not the LB7 thus far. Is there a different clearance relationship behind the CP3 in the LB7 than the LLY/LBZ? The Cummins FCA has a straight plug orientation also.
Additionally, I have replaced FCA's (FPRV) on several 5.9 CR Cummins and Duramax engines before. The symptoms exhibited by such vehicles were: rough idle after start, less than desirable rail pressure and inconsistent rail pressures @ idle and high idle. I have also modified my own FCA's to produce wanted results when performance upgrades have been performed. I haven't had a modified FCA in a stock environment produce faults so far. However, I have done modifications to stock FCA's where fueling upgrades were performed to the rail and CP3's (ie: arson kits)and more fuel was needed.
 
#13 ·
The FPR I have in is straight, so I guess it is for an LB7. I have not had time to put my old FPR in yet to see if that solves it. Otherwise the CP3 runs strong and I have not given up on PD yet. Garlen
 
#15 ·
My first guess would be they sent you a LBZ pump and FPR but it appears you have the right FPR so I don't know what else to say.
 
#17 ·
Its deffently the fuel pressure regulator i have seen a couple of these cases and the regulator solved it!
 
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