Cummins ISB 5.9 Cranks but no fire-ECM power.

[glamisorbust]

99 Holiday Rambler Endeavor 37CDS4 with Cummins 5.9 and Allison 3060. 180k miles. Just did a lot of major repairs including the following:
-Cylinder head rebuilt, including new OEM sensors and cam sensor.
-Rebuilt VP44 injection pump.
-New cooling fan from source RV, and bearing.
-All new belts, hoses, thermostat etc.
-Refurbished cummins ECM.
-New OEM Bosch injectors.
-Billet aluminum tappet cover(better seal than OEM).

Here is the issue: The coach was running when parked, but leaking water from the water pump and small leak from head gasket aging out. The gasket on the tappet cover had a bad leak too. So I decided to pull the head and have it rebuilt, clean it all up and put everything back together.

It will crank but not fire. Got a breakout box from cummins to verify the VP44 is in good working condition. It fired right using that tool. The stock ECM ended up failing somewhere after I took everything apart. No idea why. Maybe because it was covered in oil.

I have tried 5 different ECM's including the OEM one, and only one out of those fired it up. But the tune was wrong, making it undriveable. So I got a $2000 OEM refurbished one from cummins. It has been programmed properly, but this thing still fails to fire off.

I don't think I'm getting good power to the ECM, due to the lift pump also not activating. I have a suspicion the ignition key has something to do with it but haven't checked that yet. The step also doesn't come back in like it used to when you turn the ignition on. Is this most likely a bad ignition switch, relay or something else? The RV has been down for over 4 months now and I need to get it back running.

One more thing: The ignition crank works about 50% of the time, so I wired in a push button switch near the engine in an outside bay. Makes it where I don't get stranded if the engine doesn't crank.

Any help or ideas are greatly appreciated. Thank you.

[glamisorbust]

Thanks for the replies. I just replaced the ignition switch to rule that out. As I thought, it didn't do anything different than the other one. The step doesn't work, and the engine will crank but not start. Check engine light comes on with ignition, turns off for a few seconds, then right back on. I'm at a loss for words.

[Jack_Spratt]

Verify that you have fuel pressure.
I’ve had the shut down solenoid stick and bleed off
the fuel pressure. However this was on a Cat.

[Darryl_Rita]

I've had new OEM crank position sensors fail right out of the box. Try to diagnose that on the side of the road. I now carry a proven spare.

[11178adm]

there aretwo power sources to the ecm one is from the ignition switch and the other is unswiched ( hot all the time ) usually connected directly to the starting batterys this wire will have a inline fuse ussually in the battery box make sure it's not blown. if you had the cables disconnected did ths wire get reconnected a quick check to verify the ecm is powering up on initial key on the check engine and stop engine light should cycle on and off if they don't either the swiched or unswiched power is missing

hope this helps