Strange problem

[Danforth]

Ok, here's what's going on; this is a 93/auto completely stock as near as I can tell.
What it does is, it starts up and idles fine, runs fine just above idle and at WOT. Any throttle position in between and it runs like crap, as if it is starving for fuel.
It does this in or out of gear, and, where it runs smooth, makes power.
I've replaced the fuel pump and filter, checked the injectors, bled the system of air, etc.
The problem, as near as I can tell, is in the injector pump. But, since this is my first diesel, let alone first cummins, I have no idea of what to look for next.
I'm hoping someone here has run into this before and can point me in the right direction.

thanks

[boomer]

I have the exact same problem....have you found the answer? I think its my injector pump..but golly 1K? ouch! thanks man
John

[randyswelding]

put a fuel pressure gauge in it may be the lift pump

[oldestof11]

The lift pump would starve it at nearly all rpms, not just between WOT and idle. I think the AFC diaphram is not moving to allow fuel for the turbocharger. Or the pin that rides AFC cone is stuck...

[Begle1]

Can you clarify a little on the "runs like crap" bit?

Does it smoke blue, black or grey at the time?

Do you have a boost or fuel pressure gauge by any chance?

It's very bizarre if it runs fine at full fuel but not at 3/4's or 1/2 fuel. I've never heard of that before.


I don't think the AFC would have anything to do with it; a problem there wouldn't go away at WOT.