Hello,
I have a 93 D250 1st Gen Cummins and every once in a while the throttle will race. It usually happens after I have been at speed on the highway. Feels like the engine is going to run away. There is nothing I can do while driving to stop it or slow it down. When I come to a stop light, it takes everything I have to keep the brakes on and when I let off the brakes she races to about 35 mph with no pedal input from me.

Any ideas?

 

Something in the throttle linkage sticking?

 

Linkage is clean and free. That was my first thought as well.

 

Something sticking internally?? I can't really think of anything else that would do it.

 

have you tried adding a return spring to the throttle ever? also has any work been done to the injection pump recently?

 

Throttle lever has a return spring and no work to the pump.
This just came out of the blue. No amount of pedal pumping or revving makes any difference. It just stops doing it whenever it wants to.
I was hoping this was a common issue with an easy fix.

 

I have not been able to do anything to her lately. There are two new developments though.

1-She is now at a high idle constantly. When I put it in gear I can cruise at 30-40mph without touching the throttle.
2-When I shut down now she continues to run for about 30 seconds at a perfect idle.

I have driven her three times in the last month and this has happened every time. Key out, perfect idle for about 30 seconds.
VERY Strange.
HELP!!!!

 

sounds like your injection pump may need a rebuild. it should be shutting off when the key is turned to the off position. almost sounds like it is running away.