1995 dodge cummins auto trans ,truck started surging at idle when hot after pulling three horse trailer home, does not do it all the time, no surging when driving. Drove about 200 miles yesterday with pulling trailer and no problems. Anyone have any guess whats going on. THANKS

 

How low does the idle go when its surging? id try adjusting the idle to 7-800 rpm and see if it still does it

 

Yep, what he said, around 800 rpm, parkingbrake set, in "drive" and a/c on.
But I didn´t adjust mine with the engine running.....

Slev

 

From real low idle up normal but fast.why would it be idle adjustment if it just started doing it. do you think overflow valve. Thank you

 

How many miles on engine? pump parts wear just like engine parts.

 

210100 miles, pump or lift pump never touched

 

Pour some cold water water on the injection pump when it's surging.
If it stops you have a warped injection pump barrel/plunger and the pump needs to be replaced or rebuilt.
It will get worse...

 

Thank you I Will try That