Cummins NTC-230 idle problem.

[Dave Shepard]

I've got a 1979 IH 2275 with a Cummins NTC-230 that doesn't like to idle properly. When you rev the engine up, it doesn't like to come back to idle right away, it hangs for a second. Makes it really hard to shift. It's done it since I've owned it, and I've tried replacing the fuel filter and fuel line. I am wondering if I might have an air leak somewhere, or if the PT pump is shot or some other ailment. It's an off road truck, just moving dirt around the farm. Any thoughts appreciated. Thanks.

[loggah]

Does it go back to idle quickly if you move the fuel lever on the pump by hand?? i know it may sound foolish but i had a IH 2500 with a 350 cummins in it and had to put a real heavy return spring on it for it to idle back properly. I also left the jake on to help with shifting ,that pulled the r.p.m.s down pretty quickly.

[snowstorm]

have you looked at the pedal and the hinge were it bolts to the floor. my ih will stick there since it only get used in the winter

[nk14zp]

If it's not the linkage it's sucking air.

[turbo885]

try loosening the fuel cap

[hardtailjohn]

Most likely sucking air. One place that is very common is the tach cable drive seal on top of the pump. Pull the cable and pack it with grease and see if that helps. Any of the fuel lines, especially the suction lines are suspect.  It could be a mechanical problem with linkage or something like a small rock under the heel of the throttle pedal, but usually it's an air leak.
John

[Autocar]

Probably crazy to bring this up but could it be a hi idel that just needs to be switch off ?

[Dave Shepard]

Pedal action is smooth, no leaks that I can find so far, and no high idle on this engine. It does get better the harder I run it. I guess I'll just keep going. :D The only time it really bothers is trying to shift when it's muddy. Sometimes you've mired to a halt before you get the next gear. :-\