LML cp3 conversion troubles

diesel vein

New member
Apr 2, 2011
15
1
3
So I know I'm still considered a new guy but I do have some street cred on duramax forums if yall hate on me. I have done a couple of these conversions with little to no trouble and some not even having to be retuned to run well. I have been putting in stock lbz pumps.
This is a 2016 cab and chassis that had the classic cp4 failure. I installed lbz pump and new lml injectors and started and ran like a top, but anything above +- 10percent throttle it will stutter and stumble and shake and almost die out. Sometimes it will. I thought, well maybe it needs retuned. Nope... same thing. I isolated the pulp return line to rule out a kink, isolated the fuel tank and sucked fuel out of a bucket into the fuel filter, no codes, desired and actual rail pressure are very close through it all. I replaced the fpr on the pump to be sure, and removed the regulator on the rail and cleaned. Wasnt very dirty....
I sweated on this beast all day and am out of gas on it. Wow. Does anybody have some suggestions. At idle it will rev to 3k for a second then cut out sputter and rattle and almost die. Then with it floored will hold at about 1500 to 2000 rpm but runs awful while it does. Purrs like a kitty at idle. Thanks

Sent from my SM-G889A using Tapatalk
 

2004LB7

Well-known member
Dec 15, 2010
2,829
74
48
Norcal
Did you clean out the rails and lines from any metal particles ?

What is the commanded and actual fuel pressure when it stumbles at higher rpm?
 

diesel vein

New member
Apr 2, 2011
15
1
3
The rails I didnt remove, the lines i did. The commanded and desired is together very close the entire time!

Sent from my SM-G889A using Tapatalk
 

gmac32

Member
Dec 8, 2009
265
3
18
bellville ohio
I have done quite a few and never had any problems. Is the tuning segments correct for that truck? I have seen that happen before with the wrong operating system
 

diesel vein

New member
Apr 2, 2011
15
1
3
I double checked with the tuner ... they seemed confident the tuning was correct. It's tough finding good delete tuners any more..

Sent from my SM-G889A using Tapatalk
 
Last edited by a moderator:

LBZ

Super Moderator
Staff member
Jul 1, 2007
9,548
9
38
42
B.C.
I’d be looking close at everything you unhooked and unplugged again.
 

diesel vein

New member
Apr 2, 2011
15
1
3
Reman lbz. I still have the green sensor from the old pump plugged in and the plug with yellow and black wires in the lbz fpr.

Sent from my SM-G889A using Tapatalk
 

diesel vein

New member
Apr 2, 2011
15
1
3

This is spot on exactly what the truck is doing. Should I get more pushy with the tuner?

Sent from my SM-G889A using Tapatalk
 

JoshH

Daggum farm truck
Staff member
Vendor/Sponsor
Feb 14, 2007
12,966
32
48
Texas!!!
I've seen similar problems from a bad injector return regulator. They sometimes get contaminated when the pump fails and sends metal through the system.
 
  • Like
Reactions: Bdsankey

diesel vein

New member
Apr 2, 2011
15
1
3
The return regulator is what it was. Thanks a lot y'all. My day got a lot brighter when that got fixed.

Sent from my SM-G889A using Tapatalk
 

Users Who Are Viewing This Thread (Users: 0, Guests: 1)