I just bought a 95 with 5.9 cummins. This is my first Dodge, first diesel and I'm having a bit of a problem. When I drive at a constant 45-55 or 75 mph the truck seems to cut out and fluctuate up/down by about 500 rpms. I havent noticed it at any other speeds yet. I cant tell if this is a motor, computer, or tranny problem. Anyone ever seen anything like this? I also noticed that after a cold start the truck runs really rough and kills if I let off the gas in gear. Could be related? Thank you,

~Ben

 

I hope your not running gas in it

the running rough after cold start is normal, but what I'm wondering is when was the last time you changed the fuel filter and had the tranny serviced. that could be your problem

 

Sounds like aan air leak in the fuel system. Change the fuel filter and check all hoses and connections from the tank to the pump. Also check the transfer pump pressure.

 

I'll call tomorrow and find the service records... if they have any. Thanks

 

It would be less trouble to just change the filter.

 

If the fuel filter doesn't help you might want to have the pump looked at. A friend had the same happen to him and he had to have the pump rebuilt. Hope this helps.

 

I think I have it fixed. It took 30 minutes and a lot of gun cleaner before I had all the gunk out of the tps. It seems to be working just fine now. As for the idle, the guys at the diesel ram forum taught me how to adjust it and it runs like a top now. Thanks for all the responses.