Hi guys, new to the forum and this thread is helping me enormously do the injectors in my '03 duramax. Question for you though, there is a bunch of junk in one of the injectors on the drivers side (which I'm assuming may be the bad injector most likely?) and was concerned about the possibility of the injector pump going bad and sending crap through the fuel lines and right to the injectors--which would suck because then my new injectors would immediately begin collecting this debris again. However, in doing more research, it appears the injector pump on these trucks does not exactly work the same as it does in say, my 6.5 diesel, where there are a ton of little parts that tend to go bad eventually. it seems more like a supercharger to get the fuel pressured and to the common rail. is this line of thinking correct? and if so, does this mean that if there are no other signs of injector pump failure while driving or idling, etc, that the debris may just be the result of 200,000 of junk buildup/the injector going bad?

Thanks in advance for any help you guys can give!!!

 

The debris isnt actually in the injector when its running. it falls in there when you take the high pressure lines off. Dirt and grime get into the long nut for the injectors and since there is a bend just after it you can clean it out very well. Use a pick and some brakeclean, easy off and compressed air to get all of the dirt cleaned out of there and then inspect the seats for corrosion, if they are bad you can send them out to see if they can be cleaned otherwise you can replace them for around $90 each. Suck the debris out of the injector inlet with a vacuum.

Once reassembled and the high pressure lines are torque down, fill the gap around where the line goes into the nut with some sealant/gasket maker to prevent dirt and junk from getting in there.

You are correct on the pump, it is simply a constant pressure pump. It makes whatever fuel pressure the computer tells the regulator to tell it to make. The RPMs do not really matter in stock form. However GM does not expect the pump to be able to make full pressure (165mpa or just under 24,000psi for the lb7) at idle. It all depends on the fuel and pressure commanded. At idle the injectors dont need to stay open long and thus the pump can keep enough fuel supplied at a high enough pressure. Start making the injectors ask for more and the pump needs some more speed to keep up. Everything has its limits though. What im getting at though is that its not like a traditional pump where a lot is dependent on speed. The pump also pulls the fuel from the tank via a little gear pump on the rear of it.

The signs of pump failure is low power basically. From there you will determine if it can hold rail pressure, and from there run a return rate test by isolating the pump return from the rest of the system and recording the return rate of the system. If the system returns less than 35ml in 15 seconds then the pump is suspected to be bad. If it is over 35ml in 15 seconds then injectors or a leaking fprv are suspected

 

Thank u so very much for the tips&tricks. It makes the job easier for me.

 

This has to be one of the most popular DIY posts ever and rightfully so. I'm getting together the few tools I don't have and parts necessary for the job. I've read this a few times as well as other forum sites on the subject. I don't have a torque wrench and need to know what size and ft lb limit I'll need; also, is there a reference somewhere that gives the torque specs? Read that some replace the thermostats while doing the injectors... my 01 has 130K and this is the second set of injectors. No problems with temp, just want to take advantage of an opportunity if recommended.

Many thanks to all who have posted to this thread, your willingess to share you knowledge will prove to be very valuable to guys like me.

 

one that goes up to 150 is fine enough for a torque wrench.

 

I would also consider replacement lines if possible.

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Many thanks to all , this was a great thread! I will say the drivers side is a bit more than a PITA. Having the right tools and many variations of them is a huge plus, actually closer to a necessity. I replaced the fuel lines, and I will say that I would do that every time. Every thing worked out fine, she started right up. Going to run it for awhile the look into EFI live.

 

Just finished changing my injectors with the great help from this thread. Thanks!!! Just one suggestion on upper valve cover removal...... tried prying off as suggested in this thread but had no luck..... took small piece of wood plank.... 3/4 inch thick x 2in wide x about 8 to 10 inches long and put it against top corner of valve cover and barely hit it with hammer a couple of times..... valve cover came right off with no problem. But great write-up.

 

Danny THANK YOU a hole bunch. I just got done replacing all 8 of my 2001 LB7 injectors. Your post got me by with out a hitch specs and all. I could of had it done under the 14 according to the dealer, but I forgot to get the return line seals and ended up replacing cracked fuel lines and the T-stats. I guess I should of documented the driver side to compleate the post. LOL..... Thanks again you rock ....

 

Ok guys I replaced my injectors (LB7 2001) a few weeks ago and went really good, because of this thread. Today I picked up our toy hauler from storage (32 foot fifth wheel Forest River Sand Storm) and absolutely no smoke…. Also on level grades from a dead start it took off in 2nd gear no problem and accelerated to 55 before getting on the freeway (California speed limit for trailers, boo). We bought our Sand Storm last year and the truck has had bad injector for over 2 years. This was the first time pulling it with it fixed and what a difference. Danny again many thanks…..