I recently picked up a 1991.5 W250 IC CTD Reg Cab 5speed 4x4. The previous owner had said that they played with the injection pump and I have no clue where to begin trouble shooting what he did.

When a person presses on the accelerator pedal in a normal situation; a touch of the pedal would result in am increase of engine rpms proportionally to the amount the pedal is depressed.

Well.... When press on the accelerator pedal, the engine slowly revs up but no change in rpms until the pedal is pressed more than half way, then it ramps right up?? Compared to my non IC truck this feels way different and it feels as though it lags until the turbo spools up and then it takes off.

When I drive it, say in third gear I receive no acceleration until I depress the accelerator more than half way down then it ramps right up and takes off with a moderate amount of black smoke.

Cruising is a no go; it is either all out revved up or northing???? Is there a write up or a way to return the injection pump back to stock?

Thanks for your help

 

Try reving the engine with the linkage on the pump, see if there is a difference.

Also your truck has a VE pump not a VP44, thats the 2nd gen 24v.

 

sounds like you might have some slop in throttle linkage somewhere