Chevy and GMC Duramax Diesel Forum banner
  • Hey Everyone! Enter your ride HERE to be a part of this months Ride of the Month Challenge!
1 - 5 of 5 Posts

·
Registered
Joined
·
2 Posts
Discussion Starter · #1 ·
I have a 2002 LB7 with 211k miles, truck is stock other than Fass lift pump, 4” straight pipe, and AFE intake.
Recently, I was driving the truck home and when I got about 2 miles from the house, it started knocking terribly, and misfiring, but only at idle. I got it home, and discovered that the fuel line just under the cab was very rusty. I was worried the it was rusted on the inside of the line too so I started checking everything downstream from that point for pieces of rust. I pulled the FICM off, and inside there was a large amount of bits of rust. (The factory fuel filter probably would’ve stopped the rust from making it that far, but the previous owner bypassed it when he installed the Fass lift pump.) So, I flushed the FICM out, reinstalled it, along with a new set of stainless fuel lines from the sending unit all the way to the engine bay, and reinstalled the factory fuel filter.
Before this happened, my injector balance rates were within spec, now I have two injectors that are not within that range (#3: -7.0, #5: 7.9). Fuel pressure looks good.
I’m thinking the rust particles made it to the injectors, causing a the knock and heavy vibration. But, I’m still new to diesels so my guess doesn’t mean much.
Any input would be appreciated.
 

·
Registered
Joined
·
363 Posts
I'd plan on pulling & cleaning all fuel supply lines from FICM to CP3 to injectors. You should probably plan to replace at least the 2 injectors that are out of spec. Conventional wisdom says to go ahead & do them all while you're in it that far, but that's a call you'll have to make, depending on the age or your injectors & what kind of value you put on your labor. I have just finished replacing 6 injectors that I didn't bother with last fall when I just replaced the 2 that were out of spec & causing a knock. If yours are both on the same bank, I could see just replacing that side, but if your having to open up both heads...
 

·
Registered
Joined
·
363 Posts
I'd also plumb the factory fuel filter back onto the fuel system if you can. No reason not to have the additional filtration & should be no issues with the FASS pushing fuel through it.
 
  • Like
Reactions: Ron Nielson

·
Registered
Joined
·
2 Posts
Discussion Starter · #4 ·
I'd also plumb the factory fuel filter back onto the fuel system if you can. No reason not to have the additional filtration & should be no issues with the FASS pushing fuel through it.
Thanks for the reply. I reinstalled the factory filter, not sure why so many people bypass it when they install a lift pump.
 

·
Registered
Joined
·
1,237 Posts
Thanks for the reply. I reinstalled the factory filter, not sure why so many people bypass it when they install a lift pump.

Probably because it's a REAL pain in the ass to change the filter on the factory head. I've done mine over 40 times so far and it STILL SUCKS!! I also have an after market filter behind my lift pump but I left the factory filter in-line just as extra filtration.
 
1 - 5 of 5 Posts
Top