need help on a lb7

[buster-717]

i have a 2004 with 105000 on it. in the last month or so its sounds like the idles fluctuating but the tach stays still. you can hear it at the tail pipe and at the motor and sometimes you can even feel it in the brake pedal. i took it to the dealership and they checked the injectors and said it wasnt them and that the highest reading was 3.0 ? they said there was no codes and couldnt find the problem. the fuel filter was changed maybe 5000 miles ago to, so i need help asap thanks.

 

[JMK777]

are you running a programer? lift pump? could be fpr on cp3

 

[buster-717]

are you running a programer? lift pump? could be fpr on cp3

no its bone stock the only thing we did is cut the muffler off

 

[blk smoke lb7]

Sounds like to me a fuel presure reg sticking.Do you run any 2 stroke in the fuel? If not try putting in a quart per fill up.The lbz fpr i just installed was used and was making the truck surge since ive added 2 stroke it runs much better and the surging went away

 

[ecc_33]

i bet its the FPR on the back of the cp3. I have a lly doing the same thing that i have to fix next weekend

 

[buster-717]

i run tranny fliud in my fuel

 

[JMK777]

i run tranny fliud in my fuel

isint that red? I dont want to ge cought with red diesel in my tank

 

[buster-717]

lol yes it is. what is the fpr and cp3 ? im new at the diesel thing so give me some slack lol

 

[ecc_33]

The cp3 is the injection pump on a duramax. The Fuel Pressure Regulator bolts to the back of the pump via 3 torx head bolts.

 

[buster-717]

The cp3 is the injection pump on a duramax. The Fuel Pressure Regulator bolts to the back of the pump via 3 torx head bolts.

is there any way to find out if thats the problem or just to replace it? wonder how much they run price wise?

 

[ecc_33]

usually i will log fuel rail pressure with efi live and see if the idling rail pressure is high and fluctuating. If so the FPR is usually bad.

 

[DIESELMAFIAPER.LB7]

Atf hasn't died my fuel red? But maybe it eas already red:roflmao:.......anyway back ot x3 on fpr

 

[JustinD]

X2 run some 2 stroke it MIGHT clear it up for a while

 

[Kspen90]

isint that red? I dont want to ge cought with red diesel in my tank

On road diesel has green dye in it to designate it as on road fuel, adding red ATF will turn it black. Nothing to worry about with a tank dip but, atf does have friction modifiers in it that are supposedly bad for your engine. Theres a thread on it somewhere.

 

[R_F_F]

Is your AC on when it's doing it? The AC kicking off and on changes the idle slightly. My old chevy gasser once had a fluctuating idle and I couldn't figure it out till I realized the freon was a little low causing the AC to kick on and off lol

 

[buster-717]

no my ac isnt on but i first thought that when this all started cause thats kinda what it sounds like.