Hey guys, I got a 2011 Duramax lml, about 140,000 miles now. MY problem is that I'm having erratic fuel rail pressures from anywhere from 3/4 throttle all the way to wot. I've had two cp4 pumps go out on me due to algae from the previous owner. The first pump went out while the dealer was driving to my house, so they covered all the replacement of it. Said they cleaned the fuel rails and replaced the pump. After the second cp4 went out on me I had a shop do the cp3 conversion on it. During the down time while the first pump was out, I dropped the fuel tank and put a sump kit in and that's when I noticed the algae. So I cleaned the tank and installed the sump and then put algae killer in the fuel for a few months to make sure it was all out.
Now the problem arises when I'm either passing someone on the interstate at about 75, if I give it 3/4 throttle the fuel rail pressure will climb to about 23k but then get erratic. not bad enough to suggest fuel rail drainage but a definite loss of power. It will do the same thing when I'm at a stand still and launch it, it will go through up to third but when the torque conveter locks then the truck starts losing power the rail pressure will hit 29k but can dip down to about 19k and looks like an earth quake chart.
Things I have done to the truck are as listed: air dog 4g lift pump, egr full delete, 4" exhaust turbo back, stock fuel filter delete bowl, h@s minimaxx tuner, currently set on performance tune. Was going to drop it a few levels to see if it still did it and broke my door handle cable getting out of the truck in my shop.
Ive replaced fuel filters several times, had the lift pump pressure verified at 12psi, replaced the FPRV in the fuel rail due to metal shards being in it, months later today I have checked it again and it was perfectly clean, I had the cp3 pump maxed out by the same shop that installed it and they said it tested at the good range. I'm kinda at a loss for what else it could be, Just hoping you guys could help me bat around a few more ideas that I could check out before doing the dreaded and bringing it to the dealer. Any ides would help. Jon K.
Now the problem arises when I'm either passing someone on the interstate at about 75, if I give it 3/4 throttle the fuel rail pressure will climb to about 23k but then get erratic. not bad enough to suggest fuel rail drainage but a definite loss of power. It will do the same thing when I'm at a stand still and launch it, it will go through up to third but when the torque conveter locks then the truck starts losing power the rail pressure will hit 29k but can dip down to about 19k and looks like an earth quake chart.
Things I have done to the truck are as listed: air dog 4g lift pump, egr full delete, 4" exhaust turbo back, stock fuel filter delete bowl, h@s minimaxx tuner, currently set on performance tune. Was going to drop it a few levels to see if it still did it and broke my door handle cable getting out of the truck in my shop.
Ive replaced fuel filters several times, had the lift pump pressure verified at 12psi, replaced the FPRV in the fuel rail due to metal shards being in it, months later today I have checked it again and it was perfectly clean, I had the cp3 pump maxed out by the same shop that installed it and they said it tested at the good range. I'm kinda at a loss for what else it could be, Just hoping you guys could help me bat around a few more ideas that I could check out before doing the dreaded and bringing it to the dealer. Any ides would help. Jon K.
