LB7: LB7 fuel rail pressure wont build

ThatBlueDuramax

ThatBlueDuramax
Sep 24, 2017
8
0
0
Hackettstown NJ
Today i was just driving normally and i peeked over at my fuel rail pressure gauge on my insight and i noticed the pressure wouldn't rise past 10,000kpsi. i gave her more throttle even full throttle and still would go past 10,000. so i thought hmm maybe i just needed to turn the tuner up (efi live), i tuned it up to tune 5 and itll usually get up to 23,000 at WOT but nope at WOT still wouldn't go past 10k and was lacking a lot of power. No codes concerning fuel problems and i do have a lift pump. injector balance rates were normal. PLEASE HELP ME FIND THE PROBLEM
 

2004LB7

Well-known member
Dec 15, 2010
6,990
2,146
113
Norcal
No codes doesn't really mean anything. Tuner could have turned them off or changed the parameters for setting them

What pressure do you get at idle and in neutral pressing the throttle? Does it go higher?

Can you run efilive's DVT controls to test pressures?
 

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
21,681
5,835
113
Phoenix Az
pretty sure he means when you are cruising down the road and trying to get it to go above 10k, what is the desired at WOT or anything that should be going higher than 10k?
 

MAXX IT OUT

<<<IT WORKS
Mar 1, 2013
1,780
37
48
Des Moines, Iowa
I am glad someone else has had this issue, because I was going to start the a similar thread. I was towing a trailer today and the truck didn't want to get out of it's own way. I also tried all my different tunes, not much differents. I took this video so show what was going on. This was taken at WOT, ECT were higher than I thought they should be, and EGT were at 1200-1300. Funny thing was that after I parked, in park it would build full rail pressure and on the drive back everything was fine.
https://youtu.be/9T9xTPQU-xo