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Discussion Starter · #1 ·
I am coming hat in hand looking for insight and helpful opinions about a P0087 Low Fuel Rail Pressure code and a solution “I think” I have. I’m a long-time lurker with a below average post count. I scour the pages to learn. Because of this very valuable resource I have been able to solve most issues I have run into owning diesels. I have done my research across various platforms. I think I have a path forward……just need input before I head down a rabbit hole only to back out 3 days later.

Backstory
I use this truck as my daily driver for work and play. I bought the truck in Nov 2019 with 179, xxx miles and now has 309, xxx. Probably a little light on miles it could/should have due to COVID and reduced driving during that period. Still gives you an idea of yearly miles. I do not tow anything but a flatbed trailer or a boat. Hauled about 8,000lbs of landscaping rock 3 times…...other than that it is a boat only or a dump run. The Appalachian Mountains dead head in the area I live in North Alabama so there can be some long hills and 6% grades from time to time.
Its only happened twice. Both times pulling a 19’ fiberglass center console. Axle is rated for 3500lbs. I think I remember reading one time it should weigh about 3200lbs loaded with fuel.
The first time was a trip to Grenada Lake in December 2021. About 2/3rds of the way there it started. Continued for the rest of that drive and the drive back. It’s a long flat drive west of me. Any hills I encounter would have been leaving Alabama. There is rises in the road but not hills past that. Got home put a fuel filter in it. Immediately started to leak fuel back to the tank overnight and needed to pump it up in the morning, Rebuilt the head, still done it so I replaced the head. Never saw the issue again based on driving habits till last weekend.
Second time it done it I was pulling the boat again. I pulled the boat about two hours south. Started out about 3am. Never saw it once. Coming back home outside air temp was high 90’s. Stopped for diesel half way home. Put ¾ of a tank in it. Pulled out to a four way. My direction was up a hill (probably a 100’ rise over a quarter mile). Limp mode half way up. Nursed it the rest of the way home doing the usual resets along the way.

What I have done
1. Ordered an Edge CTS3. Will be in Monday for install that night. While waiting on that I have also done the following
2. Ordered a Kennedy fuel port gauge. Tested before I replaced the filter at 2.5 in hg. Replaced fuel filter and tested at 1.75 in hg. Picture is post-filter change. Something interesting to me is that even while revving the engine it may have risen .25 in hg but I feel it did not rise at all. Pinching the supply off the filter head to the CP3 it drew into a vacuum and I quit at about 15 in hg.

Motor vehicle Speedometer White Automotive tire Automotive design

3. Looked the engine over. Fixed a loose turbo inlet horn and what looked like a leak at the turbo intercooler inlet because of the oil build up around the clamp area.
4. Bottle tested the FRP. No fuel in the bottle at idle. In park revving the engine. Nor while driving a 10’ish mile circle with WOT 10-12 times.
5. Cleaned the fuel cooler
6. Imma call it a “*******” bottle test of the injectors and CP3 pump. What I mean by that is nothing is calibrated equipment and I’m doing “large chunks” of testing to determine a direction. Heck the process I used may be all wrong. I have no way of increasing rail pressure other than through the accelerator. I pieced together several ideas from other users and research material to come up with this.
7. Bottle test

Step 1 - I removed the return line to the fuel cooler, pulled the two plugs in the engine compartment and started the truck for 15 seconds. I had almost 150 milliliters of diesel in a paint mixing cup the first time and I was just trying to make sure the lines were primed. The second time the results were identical.

Drinkware Cup Fluid Line Ingredient


Step 2 - I then moved to the return rails of each bank of injectors and isolated them. Ran each of those lines in a paint mixing cup and left the return line to the fuel cooler in its own cup. Cranked it again for 15 seconds. Probably less than 2 ounces (prolly closer to 1 ounce) in each injector bank cup (the cup started at 50 milliliters and with it sitting flat it came nowhere near that). I would even call it the same amount in each injector bank cup. I ended up with just over 50 milliliters in the return line cup at the tank. Because these do not add up to what I had in the first step.... I am aware that to compare tests you have to remove any variables between tests. I did it twice to ensure full lines. These are pics from the second attempt. Thoughts!?!

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Step 3 - Next I put the two big plugs back together and started the truck and let it idle for 30 seconds. I had shy of 50 milliliters in the passenger and driver cups each (less than 100 milliliters added together). At the fuel cooler/tank return line I had close to 650 milliliters.

Green Paint Tin Gas Cylinder


8. Buttoned it all back up

Now based on that I am starting to focus on the CP3 pump. Like the title says it takes a village.......I need you guys to bring me back from the ledge.

Questions I have are -
  • Is there any validity in the bottle test I performed on the fuel system?
  • Should only CP3 return be leaving the return line at the fuel cooler if the injector return lines are isolated at their respective return lines? Could anything else be contributing to the amount of fuel seen there?
  • What are the allowable return rates for injectors/banks of injectors and CP3 pump? I found info that said like 30 milliliters at each bank (4-5 per injector) and 1-2 ounces for the CP3. I am focusing on the CP3 based on the numbers I am seeing.
  • I had air bubbles in the return lines on both banks of injectors. It was not a stream of bubbles or aeration. It was 2-3 bubbles attached to each other intermittently. It surprised me. Should I be?
  • I have read the fuel line TSB and it appears it is for 2004.5 and older trucks. Should I be concerned about the fuel lines on an LBZ motor? I am currently trying to source the hose that is called for. I intend on doing it more because of age rather than the TSB. Just looking to prioritize and/or not overlook any issues that may affect the “*******” test I have already done.
  • What else should/could I do to aid in nailing down or eliminating variables until the Edge arrives?
Questions or input you have -

I am asking for help. I have a lot of tools but I don't have every tool. What I lack in tools I like to think I make up for with an open mind and a great attitude.So nothing is off the table....I will try to provide info, answer questions and update info when I get it.

Next on the agenda –
  • The Edge is coming. Right or wrong I feel I have done all the things I can do without it. I intend to monitor fuel rail desired and actual before and while pulling the boat. I will update on what I have found.
  • Start pricing a CP3 unless I hear compelling reasons not to
  • EGR delete/up pipe/down pipe if I have to do a CP3.....or injectors for that matter. To me if I have to tear it down that far I may as well.
Thanks for reading, thanks for your time and thanks for your input!
 

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Discussion Starter · #3 ·
Yep.....its outstanding. It talked me into buying the pressure gauge. I was fully prepared to verify injector issues. The results, to me, point to the CP3 pump though. That's not mentioned in the Kennedy write up.......other than a note that indicates "others that have replaced the CP3" may not have done their homework. That is why I need to others to put eyeballs on what I've done so far and either agree, disagree or suggest. Thanks for taking the time.
 

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Discussion Starter · #5 ·
I can certainly appreciate what he says there but correct me if I'm wrong, I understand that to "imply" the system is completely buttoned up and if monitoring desired vs actual......a difference enough to set the code (-20 mPa) could/will occur because the return rate on the injectors is too high. In my test, If the injectors are isolated from the "main" return lines and the measured amount of diesel from each bank is within tolerance (I'm getting less than 50 milliliters per bank).....or at least very small relative to the return rate of the CP3.....it has made me think and ask for insight. I don't mind doing the work.....just wanna do it once of course. If I can get what spec is for return rates confirmed.....my luck dictates I may have to replace injectors and CP3....lol

A lot is being read into Kennedy's write up by me.....be the first to admit it. Also well aware that I'm testing a bank at a time versus the CP3. What I can't reconcile is that I'm getting 650 milliliters of hot fuel back to the the tank from the CP3 every 30 seconds at idle and less than 50 from each injector bank. Seems extremely high to me relatively speaking. Do you know by chance what that return rate for the CP3 should be? The only thing I have found is 1-2 ounces in a post. nothing in writing.

Thanks again.
 

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Discussion Starter · #7 ·
Thank you.....That's it....that's the one I read it from. Excellent write up. In fact its where I got 75% of the "test procedure" I used today. Testing everything and then testing a bank at a time is where I stopped. I also got the idea to clean the fuel cooler from it. It is an excellent write up. I don't have an individual injector test kit so that's why I stopped.

I chuckled when I read it because it ended up being a CP3 for caseyjay. I chuckled because of the cost difference between a CP3 and injectors is significant....and I was kinda biased because I had read the Kennedy white paper already and it made sense. I just knew it would be injectors for me. Not so much now.

What would you think if you returned 150 milliliters from the CP3 during the 15 second crank portion or 650 milliliters at idle (conceding that I was not able to drive the command to 160 mPa or use calibrated equipment)? In my mind, would it not be worse if I were able to command it? Was what I did worthless? I'm genuinely asking because I'm just trying to make forward progress while waiting on the edge so that I can read commanded as well as balance rates.I got time and find it hard to sit around knowing something aint working right.
 

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Discussion Starter · #8 ·
I looked that post back over again and was unable to locate the "ounces" quote. I may be wrong about it being the one that had it. I have read and watched so much material it has started to run together. I did lean heavily on it though.

It does say however that during the enhanced bottle test to look for a total injector return rate of less than 144ml and if more to replace injectors that exceed 18 ml return rate. That's a different number than what I had in my mind. I got no where near that number. Of course, I can't drive commanded unfortunately so maybe its apples to oranges comparison? But....with that much returning through an isolated CP3 the way I did do it.....its hard for me to get past.

Maybe all that I have confirmed is that I need to wait and get the Edge......see what I can learn from it and be prepared to have the enhanced bottle test performed.
 

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Discussion Starter · #10 ·
Thanks Mac. I agree. I do not have the ability to run the command pressure up just yet. Been looking at efi live this morning. Appears that it can. If it can I will run the return rate test again. Otherwise I would have to take it somewhere. Would rather stick a hot poker in my eye than have to do that….lol.
 
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Discussion Starter · #11 ·
Would like to confirm as well that if I isolate each bank of injectors from the return rail that the only fuel returning is from the CP3 pump? I did not locate/find easily where to tap into the CP3 so I disconnected the return line at the fuel cooler and "assumed" it would be the CP3 since the passenger and driver side banks were isolated.
 

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Discussion Starter · #12 ·
So I have the Edge installed.....went for a little test drive. Still learning the recording portion. Its 20 minutes to the interstate from my house. The Edge ran out of space just as I turned into the on ramp. Tried to save it and it appeared to lock up or it takes a really long time to process....a really long time. I finally unplugged it and started over. Then it started raining. Long story short....I did a little running when it was safe. Desired and actual drifted apart at around 155 deg fuel temp about 1000psi split. Otherwise it seemed to track. I got more to do with that though....I do a lot of interstate driving. should be easy.

Biggest thing from tonight is injector balance rate for #6. This is the worst I saw with engine warm (just got back from about a 30 mile ride). It got as low as 3.8.

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Discussion Starter · #14 ·
Thanks Roswell….yeah…hard to troubleshoot something that won’t stay broke! I did reproduce it yesterday without towing. On the ride home, fuel temp around 180 desired vs actual would separate at the upper 20% of max. I reviewed the data last night and saw roughly 25,500 desired and roughly 21,000 actual. It set the code once.

I appreciate the info on disconnecting the fpr…I could run the test again and feel a little more comfortable about each bank of the injectors.

If I end up going with injectors I am thinking of a lift pump to help push off doing a cp3. It’s got 310k on the cp3. Under no illusion it is still a spring chicken.
 

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Discussion Starter · #15 ·
It looks like the P0087 has been there….I just don’t run it in such a way to see it regularly.
 

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Discussion Starter · #17 ·
Roswell….yeah first test I did. Nothing in the bottle at idle or a 10’ish mile run with multiple WOT.
 

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Discussion Starter · #18 ·
Roswell, makes me think though….now that I know a little more about what/when it is setting I should run that test again. Eliminating variables…when fuel temp is low I do not see the split between desired v actual on the edge (early morning). I had no clue what fuel temp was then or if it was starting to fall on its face. Did not have edge installed.
 

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Discussion Starter · #21 ·
EMSmotorhead - thanks for the input. I’m back right of center and leaning towards injectors. Almost pulled the trigger last night but man that’s gonna hurt….gotta do some more hand wringing first. When I do go that way imma put a lift pump in. Not immediately so as to see the benefits of the injectors but in the interim till I recover from the hit. If injectors don’t fix it….CP3 is coming but will probably be next year.
 
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Discussion Starter · #22 ·
Biotec….thanks for the input. I’ll check it out. Got some time to run a few tanks through. Man if I could only be that lucky.

Agree with you on the CP3…research of late has eased my mind. Still thinking about the miles on it though is the only reason I can’t let it go.
 

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Discussion Starter · #23 ·
The pump is a win win in my opinion….on the three diesels I’ve owned I know I’ve put 2 fuel filter heads on each one and rebuilt a couple….not impressed with them. A pump will help identify leaks…maybe quicker and it is a benefit to a CP3 regardless of its age. All my opinion of course.
 
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Discussion Starter · #26 ·
update: replaced all the fuel lines with the exception of the ones under the bed on top of the fuel tank (supply and return). I the Talked myself out of those. When I put in a lift pump I'll get those. Not sure why they tell you to put two hose clamps on? I could not get the Parker hose over the second hump so there was not enough pipe left to land them "well". All the pictures I saw showed the hose butting up against it so I guess others struggled with that as well. I only put two on the supply.

The Edge I installed keeps freezing up and mysteriously losing transmission temp in multiple ways (maybe its there with no change in temp or its there with no numbers or worst case its not in the PID library at all). I called them and we reset everything. He said if it kept up they would replace it. Gonna do that Monday.

I ordered a new FPRV (PPE).

Soaked the up pipe bolts for probably 30hrs. Broke em all free for upcoming work.....sure wish I had already ordered a new FRPV cause it was right there once I got everything out of the way to get to the bolts. I'll be back in there soon enough....Along those lines I am starting to build a pretty long list of questions about EFI live specifically and then EFI Live and Canada in general. Any rescources for review is greatly appreciated. Still in research mode for now.

B.O.O.M...............Roswell broke out "Newtonian".......lol......I can appreciate Newton. He made a few good points! I really like the action/reaction blah.blah.blah.....especially as it relates to recreational transfer of energy down range. All kidding aside, I did look at the cleaner recommended....I gotta be honest.....not a fan of cleaner if I feeel its kicking the bucket down the road. I mean if it was uncommon for injectors to fail at 310k miles I'd be all over it.....or even from a routine maintenance standpoint. Seems well reviewed and one of the videos I watched there was a significant improvement in the injector rates.....so it makes me think. But I also think about two things I absolutely hate - 1. being broke down on the side of the road. 2. being broke down in a boat. Absent an absolute fix in my mind.....i risk being broke down on the side of the road with a boat. I'd probably need counseling after that!

Viscosities decrease in higher temperatures except for non-Newtonian fluids, which petrol aint. Which also means that the (CP3) pump can't do as well when it warms up. I see somebody else thinks you need to clean the injectors before you dump three grand on a CP3 or injectors. Doesn't cost much to prove us wrong...
Thanks Everyone
 
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