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Discussion Starter #1
I bought a used '02 dmax last year with 160k on it. Injectors had been done at 90k under warranty. I'm now at 183k and am getting a frequent cel for low fuel pressure under power enrichment mode. My brother in law is a tech at the local dealer and we hooked it up to the tech II. 50% of the injectors are creeping up to the 4% balance fail rate. Does anyone make an upgraded injector for these, or can I expect to replace these every 90k like clock work? I bought the truck for the trans, but $2500 in injectors every 2-3 yrs is tough to swallow.
 

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Try checking out alliant. I've been shopping around injectors for a 7.3 at work and they were recommended by 2 big shops. I guess they use titanium nozzles. Probably not what you were looking for but it might be a start.
 

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Some people have had luck bringing injectors back to life using the GM top end injector cleaning. I did it to mine, I didn't take any before or after readings, but it did seem to idle smoother and quieter. Mine is an LBZ and just hit 102k. Easy job.

Here is the write up.

How To: DIY - Injector cleaning - Chevy and GMC Duramax Diesel Forum

Lot's of reading and various experiences.

Hope that helps.

Jack
 

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Discussion Starter #4
Try checking out alliant. I've been shopping around injectors for a 7.3 at work and they were recommended by 2 big shops. I guess they use titanium nozzles. Probably not what you were looking for but it might be a start.
I'll take any improvement at that cost... I'm tired of playing musical trucks. If I could turn back the clock, I would have replaced the motor in my 04.5 dodge when it went at 145k. The new 2010 I replaced it with was a costly mistake, and here I am. Your thread almost had me looking for a cc osb, a manual won't work for my daily needs and I don't trust the autos.
 

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Discussion Starter #5
Some people have had luck bringing injectors back to life using the GM top end injector cleaning. I did it to mine, I didn't take any before or after readings, but it did seem to idle smoother and quieter. Mine is an LBZ and just hit 102k. Easy job.

Here is the write up.

How To: DIY - Injector cleaning - Chevy and GMC Duramax Diesel Forum

Lot's of reading and various experiences.

Hope that helps.

Jack
Idle seems smooth and noise is quieter than my cummins, the cel and tech II readings are what I'm going on. I replaced the fuel press reg a year ago and my BIL says it is unlikely the pump is failing.
 

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Idle seems smooth and noise is quieter than my cummins, the cel and tech II readings are what I'm going on. I replaced the fuel press reg a year ago and my BIL says it is unlikely the pump is failing.
Read the thread, there a ton of guys that did before and after balance readings on their injectors. They were able to bring a lot of the injectors back in line. Much cheaper and easier than injector work for about $30 worth of parts and an hour to hour and a half of your time.

Jack
 

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Discussion Starter #7
Read the thread, there a ton of guys that did before and after balance readings on their injectors. They were able to bring a lot of the injectors back in line. Much cheaper and easier than injector work for about $30 worth of parts and an hour to hour and a half of your time.

Jack
Read it, worth a shot. I need to look into the CAT filter upgrade as well. I bought Lucas and ran it for a couple months, but it made a f'n mess of my tool box and I stopped.
 

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I bought a used '02 dmax last year with 160k on it. Injectors had been done at 90k under warranty. I'm now at 183k and am getting a frequent cel for low fuel pressure under power enrichment mode. My brother in law is a tech at the local dealer and we hooked it up to the tech II. 50% of the injectors are creeping up to the 4% balance fail rate. Does anyone make an upgraded injector for these, or can I expect to replace these every 90k like clock work? I bought the truck for the trans, but $2500 in injectors every 2-3 yrs is tough to swallow.
Bosch and GM came out with a revised injector. Much, much better than the originals. People have had such shitty luck with 'diesel mechanic' rebuilt injectors that I'd stick with Bosch, and you can get them for $200ea.

I would definitely do the injector cleaning. It seems to make a real difference.

I'm confused as to how a low fuel pressure code was attributed to injectors? If you take the TechII and command max pressure, what does it do? Almost sounds like a weak CP3 to me. A lift pump would bandaid that for a LONG time to come, but if need be, a rebuilt (or good used) CP3 is a lot cheaper than you might think.

All that said, I would expect the 'under warranty' injectors to last quite a while, especially if they were done recently (the GM replacement injectors gradually got better).

Changing the fuel filter frequently will help, but a CAT filter conversion would be better, and lift pump and the extra filtration that comes with it would make the most difference in longevity out of all of those.

Mine has 100K+ on its' 'under warranty' injectors and they have survived 4+ years of no maint., which shocked me. :eek: :D
 

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Discussion Starter #9
Bosch and GM came out with a revised injector. Much, much better than the originals. People have had such shitty luck with 'diesel mechanic' rebuilt injectors that I'd stick with Bosch, and you can get them for $200ea.

I would definitely do the injector cleaning. It seems to make a real difference.

I'm confused as to how a low fuel pressure code was attributed to injectors? If you take the TechII and command max pressure, what does it do? Almost sounds like a weak CP3 to me. A lift pump would bandaid that for a LONG time to come, but if need be, a rebuilt (or good used) CP3 is a lot cheaper than you might think.

All that said, I would expect the 'under warranty' injectors to last quite a while, especially if they were done recently (the GM replacement injectors gradually got better).

Changing the fuel filter frequently will help, but a CAT filter conversion would be better, and lift pump and the extra filtration that comes with it would make the most difference in longevity out of all of those.

Mine has 100K+ on its' 'under warranty' injectors and they have survived 4+ years of no maint., which shocked me. :eek: :D

During the max pressure test we were seeing under the commanded pressure (not enough to trigger the light, but very close. I believe the balance rates were the big reason he was saying injectors, sounds like he hasn't seen many bad pumps. I'll have to check the records I got, but the under warranty injectors were done 2006? I'll pull the code again and post the number.

I'm new to dmax problems and mods. What are the lift pump mods? Full FASS system? I want to make the truck last and given the cost of injectors, any upgrade that extends longevity, would be a big plus. Where can I get the Bosch injectors for $200? I did a google search a few weeks back and was finding $3-350 iirc.
 

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During the max pressure test we were seeing under the commanded pressure (not enough to trigger the light, but very close. I believe the balance rates were the big reason he was saying injectors, sounds like he hasn't seen many bad pumps. I'll have to check the records I got, but the under warranty injectors were done 2006? I'll pull the code again and post the number.

I'm new to dmax problems and mods. What are the lift pump mods? Full FASS system? I want to make the truck last and given the cost of injectors, any upgrade that extends longevity, would be a big plus. Where can I get the Bosch injectors for $200? I did a google search a few weeks back and was finding $3-350 iirc.
Hmm. Sounds like the pump might be getting weak. While it's not unheard of, weak I/Ps aren't a daily occurrence on a dmax. I bet a lift pump would mask it for a long time. If the balance rates aren't too bad, the injector cleaner seems to do a good job of curing that.

Duramax LB7 Fuel Injector is a good source for injectors. They only sell good, name brand stuff, and they use what they sell. GMPartsdirect is a bit cheaper ($183ea) but they don't specify if they are genuine Bosch.

The FASS/Airdog/whatever is extremely similar to an Airdog for a cummins. Dual filters and a lift pump. Lift pump takes the strain off of the CP3 and the filters help save the injectors. win/win if you ask me. :D
 

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Discussion Starter #11 (Edited)
Hmm. Sounds like the pump might be getting weak. While it's not unheard of, weak I/Ps aren't a daily occurrence on a dmax. I bet a lift pump would mask it for a long time. If the balance rates aren't too bad, the injector cleaner seems to do a good job of curing that.

Duramax LB7 Fuel Injector is a good source for injectors. They only sell good, name brand stuff, and they use what they sell. GMPartsdirect is a bit cheaper ($183ea) but they don't specify if they are genuine Bosch.

The FASS/Airdog/whatever is extremely similar to an Airdog for a cummins. Dual filters and a lift pump. Lift pump takes the strain off of the CP3 and the filters help save the injectors. win/win if you ask me. :D
To clarify:

-no factory lift pump?
-dual filter setup would negate the CAT filter swap/ upgrade?
-I'll ask about further diagnostics/ tests, especially after the cleaning. I'll try to do that next weekend.
-Thank you!

*edit, wtf is with a core charge on a new part and furthermore when they do not offer/ support or recommend "rebuilds" :mad: $150 ea is $1200 bones (yeah, you should get it back, but new is NEW)
 

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1) yes. no factory lift pump on a dmax.
2) yep, no CAT filter needed with a lift pump/filters, but you can run 3 filters if you like.

core charge because there is no such thing as a 'new' LB7 injector. closest you can get is remans done by Bosch themselves. that is apparently considered 'new'. confused the hell out of me too.

always glad to help if the question doesn't involve HIDs or 24s, brah.
 

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Discussion Starter #13
Poked around a bit. It looks like the air dog 2 $670ish includes a lift pump, water separator and fuel filter (assume the stock filter can be bypassed?) Kennedy was also highly recommended for a lift pump $350 for the twin, but does not include any additional filtration. The nicktane setup appears to be an adapter and then a CAT Filter/ water bowl, like what is on my skid steer? The replacement cost I can appreciate since I just paid about $70 for a napa replacement fuel filter. FASS looks just like the air dog setup.

Does this sound right, any recommendation for one over the other?
 

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1) yes. no factory lift pump on a dmax.
2) yep, no CAT filter needed with a lift pump/filters, but you can run 3 filters if you like.

core charge because there is no such thing as a 'new' LB7 injector. closest you can get is remans done by Bosch themselves. that is apparently considered 'new'. confused the hell out of me too.

always glad to help if the question doesn't involve HIDs or 24s, brah.
Well that's incorrect the lift pump is integrated in with the high pressure pump.

Does sound like a weak cp3 but, I would verify what the issue is before you blow a lot of money on a lift pump!

If it is the cp3 why not just replace it? Instead of an expensive bandaid?
 

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I'll take any improvement at that cost... I'm tired of playing musical trucks. If I could turn back the clock, I would have replaced the motor in my 04.5 dodge when it went at 145k. The new 2010 I replaced it with was a costly mistake, and here I am. Your thread almost had me looking for a cc osb, a manual won't work for my daily needs and I don't trust the autos.
Hindsight is always 20 20. You have a great truck IMO. They all need something, if you had fixed the 04.5 you would probably be doing ball joints or a tranny or who knows right now. I don't think you would be happy with an OBS for your use, you can get the autos to last but the gearing combined with the power band of the 7.3 really suck (this is only from experience with stock trucks) also there are a project from the day you buy them. The power is pretty pathetic stock and without doing injectors you can only gain about 70 hp max with a chip, intake and exhaust. I would not be to happy lugging around a skid steer every day even with my manual. Then there is the ride :barf: I could go on. I do love my truck, but I don't drive it every day or tow all that often, and I like upgrading it and I don't mind the "old truck feel".

What I was getting at is that if you like your truck, keep it, they all need money thrown at them especially if you drive them every day. Use the same mentality as with your wheeler, if it fails get a better one and pretty soon you'll have a bomb proof truck.

Also, does anyone know of a good D max forum? I had a hard time finding a diesel forum that wasn't all about sled pulling or racing, once I did, there was a lot of info. It's nice getting opinions from 10+ people with experience rather then 2 or 3 here, not knocking anyone here, just sayin....
 

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Discussion Starter #17
Well that's incorrect the lift pump is integrated in with the high pressure pump.

Does sound like a weak cp3 but, I would verify what the issue is before you blow a lot of money on a lift pump!

If it is the cp3 why not just replace it? Instead of an expensive bandaid?
His hypothesis is that the low pressure is from leaking injectors. I'll see what happens after the cleaner.
 

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is the balance rate 4 in gear or in p/n? spec is 6 in gear...i often fail injectors for difference in temps too. also i would check the pressure relief on the fuel rail since your injectors dont have many miles on them i would almost look there as well just to be safe, anyrate i would clean the injectors like mentioned above. also for lift pump i recomend fass and airdog my personal truck has an airdog on it i buy my filters in bulk online and i think they were 8 bucks for fleetgaurd replacement fuel filter and then locally get napa water seperators, i replace the seperator 12 months because i had one clog and as well as a buddy of mines

as to reposter that said that a weak cp3 is probably the cause not true what goes on with these trucks is the injector starts to return fuel at a ungodly rate (i have seen 20+ mL for 10 seconds per injector multiple times) and the pump doesnt have the volume (new ones included when i first started i threw a injection pump in a rig for this reason wouldnt go over about 60 mpa when commanded and it turned out to be injectors)

73 jeep its not considered a lift pump but actually supply its the pump that makes the pressure too the fuel rail pressure regulator is what deadheads the pump to make the pressure
 

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73 jeep its not considered a lift pump but actually supply its the pump that makes the pressure too the fuel rail pressure regulator is what deadheads the pump to make the pressure
Not quite following you here....



The cp3 contains two pumps a "lift" (gear type) that supplies fuel to the high pressure portion (piston type).
 
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