Problems with lack of power

[PWalters]

yes the throttle goes all the way to the stop, went to the cummins repair shop, he said that if the lift pump goes bad the engine will stop running altogether, so now I am going to try the afc screw, I really hope I dont screw it up.

 

[dpuckett]

I beg to differ on the lift pump issue. It may run, but not flow enough fuel to run at higher power levels. With your truck, you should see 15-17psi peak, though you will have to get it up to the 2500rpm range to get that. Check return lines, fuel lines coming from the tank, etc, for any kinks or leaks.



Messing with the AFC screw wont screw anything up- you can always put it back. One thing that came to mind was the possibility of the guide pin sticking. If that is the case, it will cut your fuel by half (or so I've been told); thus the explanation for your 9psi boost. Unscrew the AFC housing from the top (4 set screws on each corner of the UFO on top of the pump), and take the diaphragm/ tapered pin out. Move the throttle back, as if to go WOT (the engine should be off at this time, though). There should be a guide pin about halfway down the "well" that will pop out as you move the throttle. IF it doesnt come out, or if it is really slow, that could be your culprit.



Daniel

 

[MMiller]

Not saying the lift pump is the definite problem, but I too have had low power no smoke etc, and switched the lift pump and got my smoke and power back. Its just an idea. The boost is numbers I got from Piers, what they had seen on trucks they work on, don't know spec for sure. I had already tweaked my truck before the boost and pyro. I was getting 27 psi with just the fuel screw adjustment on the back of the pump, before the injectors.



Michael

 

[PWalters]

On the way to work this morning, I was in 5th gear at 45mph, I let off the throttle and it didnt slow down stayed at 45. when I pushed the clutch in the engine revs went up about 500, then dropped to normal. this truck is starting to drive me nuts