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Discussion Starter #1
Hey guys. Last summer when towing my 5th wheel on hot summer days over the Rockies I would get a P0087 code. From my research this appears to be caused by old, worn injectors. So at a minimum, I'm looking at doing that this spring.

Now, since I will have the truck down, I'm wondering if it is worth my time to replace some other parts while I have everything apart? I'm teetering on "do everything because this truck is only used to do family vacations and a break down is a really good way to ruin what little time I get off of work" and "if it ain't broke, don't fix it!"

The truck has 220,000 mostly highway miles. I was thinking about doing:

Injectors
Glowplugs
Waterpump
Thermostats
Radiator (Mine was pack FULL of junk and looked horrible when I pulled it)
Fan Clutch
Carrier bearing (its a CCLB an the rubber looks bad)
Radiator hoses
Pulleys and belt are new 3,000 miles ago

Thoughts?
 

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From my research this appears to be caused by old, worn injectors.
Fuel Limp can be caused by 1 of 6 different things (high inj return rate is only one), or a little bit of all 6 combined.

Adjusting driver habits can go a long way in not pulling a limp. Like making sure you're running in TH, and dropping down into 'M', keeping your RPMs up in the sweet spot of 18-2200 Rs.

Usually your limps kick in when running below 1800 and mashing the skinny, instead of downshifting before the needed climb/increase in speed.

Pump is gear driven, and after you travel a while, the fuel gets hot and affects what could be marginal areas of the 6 mentioned. Keeping the Rs up helps the pump to overcome the fuel pressure loss from all of the leaks, keeping the dreaded P0087 at bay.

Techs seem to be fond of throwing $3k+ injector jobs as the solution, never having actually tested inj return rates. There are untold numbers of Dmax running out there with far more miles than yours...on the OE injectors.
 

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Discussion Starter #3
That is 100 percent correct. While in tow haul mode, if I shift to M and keep the RPM's up, I don't get the code.

The thing is, I would assume GM wouldn't have designed it this way, and the truck has never done this before. So after reading what I can find, I assumed injectors must be the issue.
 

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I would assume GM wouldn't have designed it this way,
GM designed yours to run on LSD fuel. We never had these problems way back when.
But now, everyone's forced to run ULSD, which after running it thru the scrubbers, additives are added back to restore lubricity...and in some cases, raise the Cetane levels.

Many of those additives are not compatible with the various seals and rubber hose materials used at the time yours was built. With age, seals can leak, hoses soften and suck flat, or kink in the bends where they didn't before.

Also, with your LBZ injectors, you don't replace the whole set when just one might be marginal.
 
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