Thanks a ton for all the tips info and pics, that's awesome. I will be doing this job soon on a 2004. Can i put in larger injectors without any other adjustments being necessary, or are thier mor things i need to know before putting beefy injectors in this thing? Thanks.

 

It is generally recommended that you get the trucks tune adjusted forthe larger injectors but some have gotten away without it. Some will lope at idle while others dont. Anything larger than about 30-40 overs will normally require tune adjustment

 

Just got through installing the 4th set of injectors in my 2003. the third set came from Pensacola were crap and barely lasted 20,000 miles. bought dealer remans this time with refurbished fuel lines all new washers. have 218,000 on it and looking for 300,000 before I start shelling out a grand a month for a new one. Thank you so much for this thread the info was invaluable .

 

youre welcome

 

Have you ever put a lift pump in it to help eliminate the injectors from going bad?

 

For what it's worth: I bought my 2002 new, off the lot. Been driving it ever since. It's been a fantastic truck and it's been used as a TRUCK - not a play-toy. I'm a specialty contractor and I even towed commercial for a few months while "touring" the country a few years ago. Put 30k miles on it in 3 months towing campers all over the country. I also fish offshore and and inshore marsh and tow my 10,000 lb offshore boat and $,000 lb inshore boat thousands of mile each year. I also tow a fifth wheel camper a few thousand miles a year in addition to trailers I tow on a regular basis for work.

Anyway, I now have 338,000 miles. My injectors have been pretty predictable and each set has gone out right at 80k miles. They've been changed 4 times so far - twice under warranty and twice by me (learned how on this thread- thanks 2500HD).

About 38,000 miles ago, I changed from using the OEM Delco fuel filters since new to Donaldson filters. The OEM (made by Racor) is a ~7 micron filter. The Donaldson is a 3 micron filter. In all the reading I've done on this subject, it seems the consensus is that over the course of thousands of miles, the internals of the injectors are sand-blasted by tiny particles of trash in the fuel. This eventually causes them to start leaking or dribbling fuel as damage to the needle and seat becomes worse.

So I always wondered... If trash in the fuel is causing the injectors to fail, why didn't GM put a 2 or 3 micron filter on when the problem was discovered in about 2003. Indeed, at that time, I got a "recall" letter from GM saying bring your truck in and we'll install a new, improved filter on it for free. Which I did. Apparently it wasn't all that "improved". Still a 7 micron filter. So why didn't GM put finer filters on? I think I found out why.

Once I switched over to the Donaldsons, I started having problems keeping the filter full of fuel. I didn't change anything else and my truck is bone-stock. Many times my truck would not start and I would have to pop the hood and pump the primer pump on the fuel filter housing in order to refill the filter and get the truck started. This was especially true when towing (and using fuel at a faster rate). Stop at a fuel station to fill up and it was guaranteed to require a "primer pump" to get restarted. Forever, I thought I had an air leak in my fuel system. But my gut was telling me it was something else.

So I did some more reading and asked some more questions on forums like this. Seems the CP3 is the only fuel pump in the system. Apparently, it's not strong enough to suck fuel out of the tank through a 3 micron filter at a fast enough rate to keep up with consumption... especially when towing. So I did some more reading and asking - I needed a lift pump. I ordered a lift pump and installed it. Just a single "factory performance" model. Not some super-duper hi perf dual pump, high volume gizmo. Just a simple pump that pulls fuel from the tank and keeps the filter full. Bingo -problem solved. Haven't had to pump that primer pump ever since (except when changing filters).

Anyway, that's my theory of why GM never came out with an OEM 3 micron (or less) filter for these things. They knew the CP3 pump couldn't handle that w/o adding another pump.

So anyway, I'm about halfway through with my experiment now. Since I KNOW that my injectors have failed like clockwork at about 80,000 miles, I also know that if these go farther, then I have extended the life of my injectors by installing a better filter and a lift pump to keep it full.

BTW, the added benefit of the Donaldson filters is that they only cost $18 each compared to the $50-$60 each for the Delco ones.

It'll probably take me another year and a half to hit the 80k mark on this set of injectors. Should be interesting. It's still possible that these injectors will still fail around 80k miles. For one thing, I didn't switch over to the Donaldsons till maybe 8k-9k miles after I installed these injectors. I'm also hoping that the problem with low fuel flow didn't damage these injectors. We'll see.

Time will tell.

 

Perfect, once you get there Id love to know if the injector life was extended.

That is the same info I had found out as well. I run a 2 micron CAT fuel filter and just did a full injector swap and fine tuned the fuel pressure on the lift pump last night so will take it for a drive tonight and hopefully all is well. I am second owner of 2003 LB7 223,000 . My buddy did a full injector replacement and added lift pump and has put over 80,000 on with no issues. I had found a great thread link on here about this vary issue and the lift pump instal was said to be the solution to injector failure problems since the design of the CP3 cannot keep up to the demand of the truck.

I started it up to check PSI off pump and motor was surging like crazy and throwing FPR code (P0089). As soon as I trimmed the spring in the return line on the pump to adjust pressure and got it down to 7PSI and runs great in garage and no code, hopefully just as well on road. We'll find out tonight fingers crossed.

 

So just took her for drive and still starts rough, runs rough at idle and motor runs louder than before and not seem to have the power it had. Ive installed injectors before on this and havent had an issue. Lift pump is the only new addition. So thinking I should uninstal that and than see how she runs? Any suggestions? And there is a slight tick in the motor bot not throwing any codes...

 

Great write-up and pics, thanks for taking the time.
On post #2 you refer to a link regarding injector service (Duramax Diesel Fuel System - Fuel Injector Service). The link works but not much info there, I realize it's not your thread but curious if you know what happened to it. I'm a newb here and sometimes long time posters have updated info.
Thanks again
Phil

 

Great thread, great pics and commentary.
Howeverrrrrrrrrrrrrrrrr,,,,,

Not to be a wise acre, but I have a couple of comments to add from my own experience of having just done this;

1) Do NOT use ball ended Allen keys.
They have six very short lines of contact in the bolt heads and (given that all LB7s are now at least 12 years old) you are likely to run across a few tight ones if it has never been taken apart before and the ball end hex key will "burr out" the bolt head.
Sure, it is a PITA to use a 5mm 1/4 inch drive bit on the ones against the firewall, but that is NOTHING compared to the difficulty of getting one out with a wrecked head.
I was particularly paranoid about getting my allen key all the way down to the bottom of the cavities to get max contact. I flushed each one out with a blast of brake cleaner using the tiny plastic straw. Be careful if you do this, it can spray right back at Ya.

2) I disagree with the suggested tightening sequence for both upper and lower valve covers, it jumps from one end to other end, then to the middle and out to the ends again.
I prefer middle to ends, i.e. start at the one that is labeled 3 and continue in sequence, finishing on what are labeled in the original post as 1, 2.

3) Oh yeah, do NOT drop anything.
The front end on these trucks is a maze of traps for small parts.
There is a corollary of Murphy's Law, the smaller the part the less likely it is to get all the way to the ground. Something like that.
In any case have a garden rake handy in case you have to rake out parts or tools.