New personal record for fuel filter failure...
Only 4500 miles!!!
A genunie Delco filter plugged up that quick in the middle of summer - so I know its not full of ice crystals from water in fuel... That must have been one crappy tankful, last tank was purchased in Moorhead, MN just off I94. Maybe some rancid bio-diesel blend, or a crusty underground tank?
Just my luck. 99K mile on the odometer, and I'll probably hang an injector next...just out of warranty.
P0087 fuel rail pressure low limp under high loads
Well, the second time this happened - only 1,500 miles into a fresh OEM Delco fuel filter - I knew there had to be something more going on, than just bad fuel.
No smoke at idle, none under load, but watching requested and actual fuel rail pressure showed exactly what was happening...when requested gets to 22k# the actual begins to fall behind, and when it peaks at 24K# or more, the ECM catches the variance and sets the code.
A helpful and knowledeable diesel tech at www.whitesmountainchevy.com of Casper, Wyoming verified that he has seen this before (P0087 with new fuel filter that is flowing properly) with trucks used to pull heavy equipment in the Wyoming oil fields. Said that unlike classic injector failure symptoms such as smoke at idle, this one initially had him 'scratching his head' until it became apparent that the weak injectors and/or weak high pressure pump caused the low fuel rail pressure code to be set due to their combined high return rates, rather than due to a restricted filter, which is usually the culprit.
In my case, it took a loaded trailer, Wyoming mountains, and hot engine temperatures.
They documented my situation at 101,500 miles - and I used my own ability to reset the code to continue the trip on to Salt Lake City. Code was reset about 12 times, total - always while climbing grades. Unloaded (empty) trip home was no problem.
2006 LBZ - 100K drivetrain warranty expiration
(A quick update on a previous thread that I will merge with this final installment.)
Received final decision from GM customer assistance on my injector warranty claim. Denied. They were very polite, and did a fair job of collecting information on the claim, but it was also very clear that two factors weighed heavily in their decision NOT to goodwill the repairs:
- Vehicle was diagnosed at 101,500 miles with high return rates on three injectors, GM tech recommended 8 new sprays.
- Vehicle was not purchased new from a GM dealer, was purchased from a private party. (Two GM customer assistance reps asked me this same question, both of the Service Managers I worked with also asked as well.)
Truck runs fine under 95% of daily use, but will set a P0087 low fuel rail pressure code when towing heavy and in the hills. It is repeatable, under these conditions.
If you read the entire thread , you can see how the scenario unfolded - first P0087 was assumed to be a fuel filter at 99K. Next P0087 was at 101500 and I paid to have a GM dealer diagnose and document as I was on the road.
Make sure you get any oddities DOCUMENTED by a GM dealer BEFORE the 100K cutoff...they aren't as charitable as they once were...
Low fuel rail pressure - searching for root cause
Started out with a fresh OEM Delco fuel filter before this trip. (The old filter lasted all winter - even through the December snap of -25F cold, without plugging. Thats a first.) Fuel level full to 1/2 tank during episodes described below, no blockage of OEM tank mounted fuel cooler/radiator.
About 1500 miles into the trip, I noticed the check engine light on. Checked and reset a 'low fuel rail pressure' code. Started watching the requested vs actual fuel rail pressures on the Edge.
Sure enough, with a stiff and gusty head wind working against the tall, shrinkwrapped boat - any hill ascended with even a medium heavy foot to maintain 60mph would predictably set the code. All of this happened while running the stock OEM tune, water temps were never over 200F, trans temps 200-220 max the whole time.
Hmmm...pulled over and looked at injector return rates at idle...nothing looked out of range, nice quiet idle, and the truck is otherwise running fine by all 'seat of the pants' measurements, until the code is set and the truck then starts running 'lopey' and low on power. When I started back at it, began watching fuel temperature. Normally it runs about 130F-150F, but today for some reason it was in the 160-170 range? All this on a sunny 75-80F spring day, Wisconsin rolling hills, with about 15K# of boat and trailer in tow...nothing out of the ordinary, really - except for the headwind.
When running the next hill, I kept my foot moderately into the throttle, watching fuel temperature...when it went past 170F and about when it hit 180F, the requested vs. actual pressures began to separate, and then *BING* the check engine light would illuminate, and the truck would start running badly. I repeated this cycle a half dozen times. There appeared to be a direct relationship between high fuel temp, and low fuel rail pressure. At one time, really pushing it - I saw fuel temperatures of 190F...that doesn't sound good!!! :(
Later that afternoon, it began to rain, the outside temperatures dropped to 60F, and the headwind and hills went away. No more codes, power felt better, and I could again easily hold 65mph with 160F fuel temps, no codes...
Whats making my fuel get so hot? Is my injection pump on its way out?
Must be warming up out there...
I have fielded 4 calls from LBZ owners already today and it's not even noon.
1) Had P0087 codes and others. Replaced pump no cure. Replaced injectors and his fuel pressure issues went away. Now he's chasing boost codes. Totally stock truck
2) Has 4 Dmax trucks pulling RV's 2) 2007 LBZ, 1) 2005 LLY and 1) 2004 LB7. The 2007 LBZ's are the only ones giving grief. P0087 both trucks, sudden onset. Totally stock I believe
3) 350k and no fuel pressure problems. Running TS MP-8 (jacks fuel pressure) and called regarding different issues.
4) 2006 LLY (actually LBZ) 300k+ hauling RV's now getting P0087. Has Edge with monitor and uses it to clear codes.
I'm thinking this is still injector related (caller #1 supports this, BUT I also think this may be one of those things like the 2001 where we can do some programming changes to address this. Unfortunately not enough of the fuel psi info is available to do this at this time.
P00087 and GM bulletin PIP4526
I recently received communication outside TDP from another 2006 LBZ owner who also hauls cargo (trailers) commercially. He had been experiencing the same P00087 low fuel rail pressure code (with limp) when the truck was fully warmed up, and while running loaded in the hills. Recently, the problem had been occuring more frequently, with less load...all symptoms identical to those I have been experiencing.
Their GM dealer had previously recommending 8 new injectors due to 'high return rates'. They did perform the physical return rate test with tubes and graduated cylinder. The truck was exhibiting no other symptoms of injector problems - no smoke, no oil dilution, etc. and had 215K miles on the factory set.
They were not convinced, were not willing to spend 4K uneccessarily, and kept on digging for answers.
Finally, another GM dealer they found on the internet had pointed out GM bulletin PIP4526 which deals with collapsing rubber fuel lines, on the draw or supply side. They replaced a section of hose per the bulletin, and have had no further issues with similar loads over similar mountains.
Hope this helps someone scratching their head over P00087 codes, with a fresh new filter and no other driveability problems. I have yet to repair my truck, but am confident this will address my issue, too. Possibly a GM tech reading this could cut and paste the contents of the bulletin in this thread.