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Duramax 6600 Welcome to the Internet's first Duramax 6600 diesel discussion forum for the LB7, LLY, LBZ, LMM, LML, LGH & L5P RPO code engines. Tips on performance, fuel economy, troubleshooting and more.

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  #1  
Old 03-17-2018, 05:50 PM
richp richp is offline
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Default The P0087 Saga Continues

Hi,

I’m modifying and moving this content from the Sticky I previously had posted in, to try to get some feedback. Moderators, if this is a problem, feel free to delete.

I just returned to Illinois from Quartzsite towing my 12,000# fiver. I have 123k miles on the '09 LMM at this point. I had no problems going down in January, but several P0087 episodes on my return last week – big hills, a couple hours into the day, lower fuel level in the tank (the usual culprits, evidently).

This is an absolutely stock truck, with auxiliary filtration, regular Power Service throughout its life, regular filter changes, and regular Chevy dealer service at the same competent location. No lift pump (duly noted, John).

Obviously, working through the P0087 Sticky thread gives possible short and long term answers. But my solution for getting home the last 1,000 miles -- starting in western Oklahoma -- was to keep post turbo EGT's in the 1,000 degree range, and never more than 1,100. I used that as a proxy for the temps the injectors and incoming fuel were experiencing. I did this by doing a lot of manual gear selection on hills. (I recall only one post in that entire Sticky thread that mentions that approach.)

My dealer has just had it for two days, and as I expected, found nothing wrong. The injectors tested solid (as they did just before I left actually). No codes were remaining, of course. And absent the load from towing a heavy trailer on hills for hours while hot, there was no way to get their equipment to register my issue. In addition, at my request they inspected all fuel lines (solid or already replaced), the fuel cooler (clean), and they found no leaks anywhere.

These are two guys who know the truck since new, have serviced it thoroughly and regularly, and otherwise have my confidence. They did offer a thought that freeing up the exhaust might help keep overall temps down and thus keep the returned fuel cooler. Coming from a dealership, I found that interesting.

But for now I'm guess I'm going to drive on carefully, and see what the future holds.

Any thoughts on the exhaust change idea from anyone? How about my strategy of using EGT as a proxy for fueling performance? Or for that matter, on any other recent developments on this P0087 code problem for medium age trucks that work hard?

Thanks for your ideas.
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In The Past: '82 6.2 Jimmy Blazer, '93 6.5 GMC K-2500, '01 DMAX K-2500, '09 DMAX K-2500
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  #2  
Old 03-18-2018, 05:56 AM
richp richp is offline
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Default A related question

Hi,

Thinking about this some more...

If I go down the road clearing my codes as they pop up (something others have done), does that accelerate wear in the injectors, speeding their eventual demise?
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  #3  
Old 03-20-2018, 08:15 AM
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Rich, the following two subscriber articles appeared here some time ago. They were written to help address the trouble code P0087 in the LMM trucks (and earlier LB7/LLY codes) that correspond with rail pressure problems (difference between commanded and actual fuel rail pressures exceeding 20Mpa).

Are high mile injectors allowing too much return fuel, which result in a P0087? GM shows in their service manuals how to perform a fuel return test using graduated cylinders that helps the technician measure fuel return flow over time. The first link shows the test setup, and explains how its used.

https://www.thedieselpage.com/members/features/p0087c.htm
https://www.thedieselpage.com/members/duramax/April2008DTCc.htm

Techs tell me that a lot of trucks that approach their 10-year mark frequently have surface-clogged fuel return coolers. Mud, leaves, you name it, all restrict air flow over/through the cooler.
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Old 03-20-2018, 11:26 AM
richp richp is offline
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Hi Jim,

Thanks for that response. I had read the first linked piece, but not the second one. The Sticky thread and John's tech piece rounded out my major research.

The bottom line seems either to be that this generation of injectors is vulnerable to wear and/or fuel viscosity changes, or the ECM programming is dysfunctionally narrow. (I include the latter because John seems to have attacked it somewhat successfully from that angle.)

My hoses, filter housing and filter have been replaced. The injectors all are strong in every test in the shop. The pump is putting out per spec. My GM guys have checked the cooler and lines, and I will do that again when I get some decent weather. (We just talked this morning about the possibilities of an auxiliary fuel cooler.) But there is no way to get them involved in more useful testing 200 miles into a day, going up some big hill towing a 12k trailer -- duplicating the problem with prolonged, sustained load and elevated temperatures. I can drive it all day unloaded in any weather, with no problem.

You know I love GM products. But pickup trucks built to work -- as our diesels are -- surely could have more longevity built into key, very expensive parts. Or is this the unavoidable legacy of always-advancing emission requirements and associated engineering compromises?

Color me frustrated and mildly disapointed...
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Old 03-20-2018, 03:54 PM
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I talked to a guy a few years ago who had a 2009 model he used to pull a 5ver that was experiencing the P0087 code problem... till he installed a large auxiliary fuel tank in the bed of the truck. He ran a fuel transfer system (don't remember the details) that cycled fuel through the aux tank and his frame mounted tank. This effectively ended his P0087 problem. Hot thin fuel, as he discovered, was a key factor in his P0087s, or at least cooler fuel masked the root cause. Jim

Last edited by More Power; 03-21-2018 at 11:16 AM.
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Old 03-21-2018, 09:55 AM
Kennedy Kennedy is offline
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Lift pump, tune it, drive it. If the conditions still exist the P0087 will set and check engine light will be on but truck will drive right through. If the instance increase significantly it's time for injectors.

I'll also note that I have done tunes for trucks that have had GM sourced injectors installed and NOT fixed the issue. I've had guys change injectors and repeat in less miles than the originals as well. Tune and move on

As for the testing quite often they will pass the stationary tests as the temp/psi/time does not accurately simulate real world.

That or just take my word for it having had injectors bench tested and seeing the obvious fail its the reason
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Old 03-21-2018, 11:26 AM
richp richp is offline
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Question

Hi John,

Thanks for your additional input. Your published materials on this also have been quite helpful to me.

Do you or anyone else know what pressure exists in the return lines from the injectors to the tank? An additional option I'm considering is a second fuel cooler, but location could be an issue, depending on the available hardware. Something like this...

http://www.jegs.com/i/Derale/259/132...RoCsDEQAvD_BwE

Any thoughts, anyone?
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Old 03-21-2018, 02:12 PM
Kennedy Kennedy is offline
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Return line pressure should be minimal. There is an orifice at the end of the line but it's open.

Cool it all you want, put a fan on it even. I've seen it all. Sometimes you get lucky, but most often not.
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Kennedy Diesel-owner
More than just a salesman-I use and test the products that I sell on a daily basis!
Superflow Lie Detector in house
2002 Chev K2500HD D/A CC Long LT 11.77@ 124mph at 7700# fuel only-e.t. needs help
2005 Chev K3500SRW D/A CC Long LT(SOLD)
2007 Chev K2500 Classic EC Short LT (Sold)
2012 GMC K3500SRW D/A CC Long LTZ Happy Birthday to me! Built 1 working day after my birthday and delivered 7 days later.
2016 GMC K3500SRW D/A CC short LTZ

Custom tuning in house using EFI Live tuning software!
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  #9  
Old 03-22-2018, 02:04 PM
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If I were faced with this P0087 problem, I would do as JK said... Add a lift pump, retune the ECM to accept a wider tolerance for an acceptable common-rail pressure differential, then keep driving it till injector replacement becomes unavoidable.
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Old 03-22-2018, 02:30 PM
richp richp is offline
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Quote:
Originally Posted by More Power View Post
If I were faced with this P0087 problem, I would do as JK said... Add a lift pump, retune the ECM to accept a wider tolerance for an acceptable common-rail pressure differential, then keep driving it till injector replacement becomes unavoidable.
Hi,

Yeah, but that is a tough pill to swallow if there is even a modest chance a second fuel cooler, better management of the level of fuel in the tank, or other less costly options could have promise.

This is doubly hard for me. First, we buy these trucks because they are supposed to work long and hard. And I don't readily accept the proposition that 120,000 miles is acceptable life for such high cost components. Second, because to adopt the strategy suggested in the above paragraph, I'm resisting the considered advice of two guys whom I respect, and who know a lot more about this than I do.

Color me conflicted...
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