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

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.

I forgot to mention that I changed filter after I put new CP3 in.

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.

It was supposed to be all LB7 pump and regulator. So if I put my old regulator in that might help.

Subscribing.... I would put the old regulator on there and see if that fixes it.

Contact Pensacola and tell them it has a faulty FPR.

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.

Misread post.

if you put the old fpr it will most probably fix the problem.

Don't waste your time swapping the FPR. You already know it's faulty. Your time is worth something, right?

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.

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

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.
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.

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.

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.

The fuel lines are routed slightly different on an LB7 VS the LLY+ engines. The later regulator will fit in, but requires EFILIVE to tune the rail valve current to get it to idle right. I know the CUMMINS uses a triangluar shape in the plunger, but the LB7 uses a square hole with a small slit going upwards from it.

Its deffently the fuel pressure regulator i have seen a couple of these cases and the regulator solved it!

The fuel lines are routed slightly different on an LB7 VS the LLY+ engines. The later regulator will fit in, but requires EFILIVE to tune the rail valve current to get it to idle right. I know the CUMMINS uses a triangluar shape in the plunger, but the LB7 uses a square hole with a small slit going upwards from it.
Very interesting, thanks. Yes, the cummins unit is triangular, atleast until you drill it out to flow more!:D I didnt know the LB7 version was square??? Thats very interesting they change the design as such. I did some CP3 upgrade kits where all that was needed was to drill out the FCA to pass more fuel. Essentially, that appears to be all that is done w/the aftermarket CP3 kits, drill out the ports on the gearotor pump, bigger spring on the cascade valve, port the fuel fitting and enlarge the orifice on the FCA.

Do you have any type of lift pump.. if so i bet if you turn it off it will stop the lopey idle. mine does the same thing something about to much pressure from my lift pump dealer says dont worry bout it wont hurt anything