Ken,
I have a ISB 275 Cummins. One time the engine quit, towed to Cummins and they said no fuel to Injectors. Need new Injector Pump. Mine uses the VP44 Pump. I said "Have you checked the fuse in the line that provides power to pump?" They said "huh". Went with them and electrical drawings and found a blown fuse. Wire that feed power to Injector pump had rubbed thru insulation and was touching ground. Saved me a lot of money.
Good luck, Glenn