Engine/Transmission (1994 - 1998) fuel pump

[oldbusguy]

does anyone know why idle speed is dropping below 500 rpm started this about 1000 miles ago this is a p pump

 

[Joe G.]

Have you tried adjusting the idle? The screw can wear a little bit and cause that.

 

[Skydiver]

Mine and my friends did the same thing around 150000 miles.
I would like to know if the ulsd is causing this.

 

[td343]

Just like Joe says above, I had this problem. I never found the cause after looking at multiple things. It got so bad that if I used my a/c and came to a stop, the engine would die. It was idling that low. My local Dodge dealer had it fixed in about 1/2 hour. It was a worn screw at the idle.

 

[oldbusguy]

thanks for the info it just seem strange to drop this quick normal wear i would think would be a slow drop not just boom and low idle i am going to set the idle up and see if it drops again also i dont think this has anything to do with usld as i only run bio 20% soy and 80%diesel jack

 

[bmoeller]

If the jamb nut becomes loose, the idle can drop fairly quick with th vibrations of the engine. With the pedal pushed down, it takes the pressure off of the bolt, and it can turn. One rev on the bolt makes a decent change in RPMs.

 

[JWashburn]

I had this problem. I replaced the overflow valve spring with one from PDR. Idle came back to spec. The spring in the overflow valve apparently weakens over time. If this isn't it, then you have no choice, but to adjest the idle.