All,

I figured I would start a dedicated thread on this subject as it is a major decision point.

How would I find the production changes in the HPFP's used on the 6.7's?

The underlying question is I have a truck in the shop being repaired. The last major service was about 5 years ago with a failed HPFP. We had all through the injectors replaced at that time. Since then about 17k miles have been put on the truck. It appears now an injector is bad (among other things, but not fuel system related). I won't re-hash everything.

So where we're at with it is the truck is a 2011 job 2. The original HPFP went about 170k miles. In its current state - it has sat out of service for about 2.5 years (the first year and a half of that it was periodically driven - every month or two - for a couple miles, the last year it has not run until the other day).

While we're in process to get the truck back in-service the big question we have is - what were the changes, if any, in the pump that went on about 5 years ago vs the original OEM from that 1st model year/2nd build?

If there is a way to verify, by way of part number from the previous service, to determine any changes that may make it less likely to grenade with contaminated fuel we may be more inclined to keep going on it. However, at the moment - we are very hesitant to drive the truck on it, regardless of getting fresh fuel in it as we proceed with the work, because if the pump is already compromised it could blow at any time. And with 2.5 year old fuel that really does not give me the warm and fuzzies. The last fuel that was put in it was from October of '23. I don't want this to be a discussion topic as it is going to bury what I need to find out in "noise", but the dealer did test it before proceeding and authorized the diagnostics (which required the engine running) without a fuel flush. I'm not too happy about it, but it is what it is and we have to move forward.

Replacing the pump alone, without a fuel system kit to rebuild the high pressure system, is a $2500 job on top of what we're already having done (if it was a job in and of itself it would be noticeably higher - because there is more tear-down to do it which is already going to be done for the other work).

Ultimately - is the added $2500 justified? I say if it saves a blown pump and a whole high pressure system rebuild again in short order (it was about a $7k job 5 years ago, Im not sure what it is today) then its worth it.

Thoughts/info?

 

Someone more knowledge than I can probably bring more to the party but if I am replacing the pump.... I would go with a DCR. There were changes over the years, coatings on parts, pinning the buckets in 2020, increasing tolerances with RP8 pumps but still has the same basic design that can grenade on you.

Additionally, 2.5 years is pushing it on the life of the fuel. Especially if there is any growth in it. That tank needs to be drain and fresh diesel needs to go in considering the cost of the repairs your doing here it only makes sense IMHO.

 

In 2020 the CP4 had 2 changes, 1 - the buckets were pinned to prevent rotation, and 2 - the maximum fuel pressure was increased from 29,000 pis to 36,000 psi. The pinned buckets should eliminate one of the failure modes, however others remain. There has been a lot of discussion as to the cause of the failures and no one here has actual data on the root cause(s). Some pumps fail in tens of thousands of miles while others last hundreds of thousands of miles. In your case your risk tolerance will dictate what you should do. If you want to eliminate all risk replace it with a S&S Diesel DCR, if you don't want to spend $2400 on the pump and can tolerate some risk install an S&S Diesel DPK, beware of cheap knockoffs. Your current pump could last a long time, but if it doesn't the DPK will only mean that the pump, the S&S return filter and fuel line to it would need to be replaced, not the entire fuel system repair otherwise needed.

 

aside from the physical pump changes....the pinned buckets, reversing the steel lines (why..i dont know), changes to coatings on the cam and rollers )supposedly), changes to cam lobes to raise psi, etc.....I think there uas been some programing changes....my 2019 will immidiately go into wrnch mode and shut off if the fuel pressure is below X, I have has 3 burst filters or connectors and each time the pcm shuts the motors off before the cp4 runs dry.


I also think there is a programing change for startup.....sometimes even in warm weather....I get a delay between push button and actiual start...my theroy is the pcm wont try to start if PSI X is not achined....could be wish full thinking.

what hasnt changed and needs to is water seperation and particle capture of fuel......I have an extra in between filter between my in tank filter and the engine bay filter....the in between filter is the only place I have ever drained water.....that does not make sense unless the intank filter can not seperate emulsifide water very well if at all.....it might be good of capturing free water .....using gravity that brings it to the bottom...but ...I have never drained any water from my in tank water drain.

another mystery about the in tank filter....I often drain particles from my middle filter....how is that possible if the in tank filter works....suspect if that rubber kids dart looking thing that seats up on the intake port....its supposed to be a one way check valve....dont know how much suction PSI it takes for the rubber dart to loose it seal and starts letting un filter fuel thru...but its happening...else...how would particles get in my in between filter if the in tank filter works?

another mystery and point of ambiguity....these so called recirculation during cold features...which I think is a ford tap dance....particles are able to ride the recirculation flow and by pass filtering.....there is some type of recirculation process in the in tank system and now there is a by pass in the engine bay filter.....does that mean by pass as in motor oil by passes...dont knoiw...but suspect is particles traveling to injectors and cp4 while these bypass/recirculation systems are engaged.


one additional benifet of the DPK is increasing the flow rate across the roller bearing s and cam...in my mind cooling effect....same effect ford try to emulate by changing the programing for the 2020 impacted vehcicles in storage problem in the hopes more flow would mean less wear.


so if you dont want to do a dcr

a. DPF
b. in between filter
c. multipurpose additives for wear, water removal, germicide, anti gel
d. if you can get bio blen that is good for cp4 lube....but bad if your truck will sit thru a tank of fuel for a while.

 

To add to this, Bosch updated the CP4 RP7 that Ford started using in 2020 which had the pinned buckets. But then, in August of 2021 Ford started installing the even more updated CP4 RP8 variant which "increased the pump’s roller shoe and tappet body clearances..." which "expanded clearances allow for improved fuel flow, resulting in better cooling within the tappet area of the pump." From the best I can tell, to this day, Ford is still putting the same CP4 RP8 variant in their trucks.

This would explain the big recent fuel pump (CP4) recall that only included some of the 2022 models, but not all... the recall was for the trucks that had the RP7 models. My truck was built in mid September, 2021 and is not included in the recall, so my truck was pretty close to the beginning of the switch over for the newer, better RP8 variant.

It doesn't seem like there has been as many reports of CP4 failures on these RP8 variants... or maybe I just haven't seen them all. From what I can tell, it seems like the changes from first, the RP7 and then the RP8 have made a good difference in the pumps ability to perform.

Saying that, if I were having to replace it all, especially on my dime, I would go back in with a DCR and be done with it.