My beloved Duramax needs help.

[jjeff]

New filter acquired it has 2 new orings let the pessimistic fun begin. First I'll thoroughly check newly replaced filter see if I can see any hint of seepage of fuel around it.

 

[5030]

I think we all share a common dislike for computerized diesels.

 

[jjeff]

Great to get in shop instead of usual desk paper pushing desk jokeying. As my backwoods pessimistic assumption seems correct occasionally, that's diesel on my hand. filter is weeping minimally from outer o-ring i believe. Makes sense considering the truck has a problem staying running after sitting more than a few days. Why would the gm engineers make that bloody filter so inaccessible? imo. This time around I'm more annoyed trying to document my trucks turmoil than having to pull that fender liner or inadequate repair methods by "professionals" I paid them to do it. Belt tensioner seems like it was properly done though. good day.

 

[jjeff]

Questions for more knowledgeable folks than me what's your method for holding o-rings in place while reassembling something like a hard to reach fuel filter, I've always used a dab of axle grease or similar around base, is there a better hack for this?

 

[jjeff]

I'm a sucker for learning hands on when around knowledgeable folks here's a picture of lower part of fuel filter weeping, it's very minimal and not dripping the shine is diesel, and is all I needed to see to justify replacing a rather expensive filter assembly. My other question is since it is weeping enough to cause problems staying running after sitting awhile cuz it's sucking minimal air has that weak cp4 high pressure pump been irreversibly damaged? Any way to tell without digging further into my Duramax?

 

[YanmarFever]

Install the new filter and make sure it doesn't leak, then if the truck runs good, I wouldn't worry about the pump.
First things first...

 

[Snobdds]

You need to get a reading of what your fuel pressure is doing. Is it dropping off under load or is the regulator going bad?

I'm not real sure if Dmax have a fuel pressure sensor, but they are not hard to add. You need to see in real time what your fuel is doing. That could point to a lift pump or leak.
We have great technology today, use it.

 

[Snobdds]

Also, fuel systems are expensive...it's the one thing to constanly monitor on high pressure fuel delivery systems.

I will die on the hill that HEUI is the best fuel system. It's not fragile and can supply enough fuel for any lite duty truck. Common rail is nice and clean, but damn is it fragile.

 

[jjeff]

You need to get a reading of what your fuel pressure is doing. Is it dropping off under load or is the regulator going bad?

I'm not real sure if Dmax have a fuel pressure sensor, but they are not hard to add. You need to see in real time what your fuel is doing. That could point to a lift pump or leak.
We have great technology today, use it.

I think I can monitor fuel pressure with my standalone banks monitor when driving just need to figure out how to change the parameters I currently have it monitor new fuel filter assembly is in I pre primed it with a mixture of marvel, power service and shh off road diesel. Orings didn't look to bad minus a little winter grit around them, lower valve was definitely on a little to tight for my liking anyway I'm hoping the lower drain valve is ok cuz I didn't replace that. Anyways left a clean white rag around filter, using off road diesel and marvel it's much easier to look for leaking. Hopefully reassembly of fender liner goes smoothly.

 

[jjeff]

So far success, trucks running at idle , no leaks or weeping yet. have to figure banks monitor out to monitor fuel pressure which I'll definitely do when I get back inside.

 

[dodge man]

If you drove the truck thousands of miles with a small air leak you might have hurt the injection pump but I doubt you did any damage.

 

[YanmarFever]

90% of the time its an improperly installed or dirty fuel filter.
I had my lift pump go out on a dodge 2500 I use to own while hauling 3 small tractors on a trailer and 250miles from home.
I limped all the way home praying, then replacing the pump and dropping the fuel tank was a bear of job and dirty!

 

[jjeff]

Waiting till tomorrow to put fender liner back so I can see if there's any fuel seeping. But so far so good. The drain valve plastic nut was overtightened the filter assembly itself was
loose on disassembly imo. Not like it really matters anymore but I think they went from the top to get filter access, previous attempt I made years ago I failed going that route, by removing the air filter assembly hence the initial check engine light cuz of a disconnected sensor on the intake when I picked it up. Did I mention what a pain in the ace it is pulling the fender liner without damaging it? Bull in China shop mentality Lol. thanks to all for the insightful help.

 

[5030]

Questions for more knowledgeable folks than me what's your method for holding o-rings in place while reassembling something like a hard to reach fuel filter, I've always used a dab of axle grease or similar around base, is there a better hack for this?

That works fine and what I do as well when required.

 

[5030]

90% of the time its an improperly installed or dirty fuel filter.
I had my lift pump go out on a dodge 2500 I use to own while hauling 3 small tractors on a trailer and 250miles from home.
I limped all the way home praying, then replacing the pump and dropping the fuel tank was a bear of job and dirty!

I can relate just fine. When I had the algae issue with my diesel Ford, I not only had to drop both fuel tanks but replace the sending units, the fuel bowl and the lift pump. Least the fuel filter stopped it from getting to the HPOP and the injectors. Was a grand in parts and I was the grunt labor.

 

[YanmarFever]

I remember your fiasco with that algae.

 

[5030]

Trying to forget. Why I religiously use Power Service Bio-Kleen biocide now in all my diesel. Don't want a repeat performance, ever

 

[Hay Dude]

Waiting till tomorrow to put fender liner back so I can see if there's any fuel seeping. But so far so good. The drain valve plastic nut was overtightened the filter assembly itself was
loose on disassembly imo. Not like it really matters anymore but I think they went from the top to get filter access, previous attempt I made years ago I failed going that route, by removing the air filter assembly hence the initial check engine light cuz of a disconnected sensor on the intake when I picked it up. Did I mention what a pain in the ace it is pulling the fender liner without damaging it? Bull in China shop mentality Lol. thanks to all for the insightful help.

You have any other problems, let me know.
Not much I haven’t seen or fixed.

 

[YanmarFever]

Trying to forget. Why I religiously use Power Service Bio-Kleen biocide now in all my diesel. Don't want a repeat performance, ever

That bio clean is not cheap, its $170.00 for a gallon, but it does go a long way....
1 oz per 20 gallons of diesel and you're ready to rip!

 

[5030]

Trying to forget. Why I religiously use Power Service Bio-Kleen biocide now in all my diesel. Don't want a repeat performance, ever

That bio clean is not cheap, its $170.00 for a gallon, but it does go a long way....
1 oz per 20 gallons of diesel and you're ready to rip!

The good stuff is never cheap. I use it because it has the MSDS label attached to every bottle and a little goes a long way. Have not had issue one since I started using it.