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

When I press on the accelerator pedal a touch the typical result would be that the engine would rev up proportionaly to the ammount the pedal is depressed. Well.... I have to press my gas pedal more than half way down before I get any results. I have checked the throttle cable for stretch and it is perfect.

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

Cruising is a no go; it is either all out revved up or northing????

Any help please

 

Maybe the throttle shaft was messed with and put back in the wrong place. If the po put in a 3200 spring that could be a possibility.
There are more experienced people here on the forum that hopefully will chime in for you. Check the sticky ve pump rebuild and on the second page you'll see the throttle shaft and what i'm talking about
Eric

 

Sounds like the breakover spring wore through. I don't have time to scare up a picture right now but maybe somebody will help you out by posing a pic of what I am talking about.

If it's not that, I've seen the nut that holds the throttle arm to the throttle shaft get loose and cause this.