The P0087 Saga Continues

[More Power]

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.

[richp]

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...

[More Power]

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

[Kennedy]

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

[richp]

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?

[Kennedy]

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.

[More Power]

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.