444 cummins mechanical motor problem

fuel inj. or fuel inj. pump, just have it ck. at real shop.

 

Sounds like its pulling air on the fuel supply. Check all the fittings from the pickup to fuel pump. Especially the o ring on the filter.

 

Could be a fuel pressure issue, have a look at the little sieve on top of the fuel pump. If it's clean have the pump calibrated at a shop.

 

those old 444 cummins had some real problems with the step timing they came out with,that was a major problem. they also had a detuned 365 version of that engine also. made them have excessive smoke at idle. lots of luck with your problem

 

Just an opinion but sounds to me like throttle shaft seals in the pump. Not idling down when you let off is usually a good sign of it. Engine not killing by key could be caused by this too. Usually a reman pump calibrated to your specs is about 500 dollars most diesel shops have them bilt ready to go except calibration which only takes an hour or so.