lol, i take it cranks to mean it spins with the starter....it doesn't spin over to mean no fire...take a multimeter and unplug the connector at the lift pump. check for battery voltage. If you have 12+ volts there your lift pump is shot. No voltage there then you need to find the in line fuse between the pump and ECM. Mine popped the fuse and also the new one when I replaced it. Turned out to be a bad pump. The fuse will be all by itself, usually taped to the harness. They wrap it up really well and its hard to see...it's just a 10 amp blade fuse with a plastic cover over it...
So, to be clear, the question is:
When you turn the key does the starter run? Does the engine itself turn over but not fire? If the engine is turning over does it sound like it's normally trying to start or does it sound like it's getting stuck or hung up along the way (you already stated that you tried changing the batteries so I'll assume that isn't the issue).
No check engine but has red stop engine flashing lights that used to not flash prime pump not working with key on...bad ECM?
Engine turns and starter runs but it won’t fire up to run the truck .. I checked the inline fuse that was taped up and it was good .. engine doesn’t hang up while it’s turning.. everything sounds normal but it just won’t fire up to run.. I changed out the priming pump with another one I know was good and priming pump still won’t turn on as I turn the key..
There’s no bad codes it’s showing the only red light blinking is the def fluid light..
just looked up what your ECM looks like you'll have to register on Cummins quick-serve and find the electrical pinout for your ECM and find the 12v power and ground wires as your plugs are different from mine
Ok I’m registered there I’ll check it out
Not sure if it's exactly the same as your engine, but my cm2250 ECM wiring harness diagram shows the lift pump and both NOx sensors sharing the same neutral/ground wire back to the battery. You could have a ground issue in this circuit.
It does sound like some sort of ignition problem, which is why your lift pump won’t kick on. I would start at fuses and relays