Fuel Problem Cummins

[JimT]

Not sure how long this has been going on or when the pump died, but did you consider that the failing pump could have been the cause of the issue?

Conversely if you're getting air into the system ANYWHERE before the high pressure fuel pump that could have been the main contributing factor to the fuel pump failure. The plungers in the pump head rely on the fuel for lubrication and any air infiltration could lead to increased friction. While it probably can withstand the occasional air bubble repeatedly running out of fuel will most likely accelerate wear along the plungers. This is my own speculation here, but I wouldn't be surprised if this is the underlying root cause of these pumps dying, especially with the old ceramic plungers as opposed to the steel ones.

I mention both these specifically because you said it takes 3-4 key cycles to get it started then runs rough. This implies that the issue is on the priming side. If it was on the high pressure side it would simply take extended cranking as opposed to key cycles (priming). It could be sucking air anywhere between the high pressure pump and the tanks.