cm2200 stand alone dies after 3 seconds

I am working on a 2010 6.7l cummins with the CM2200 ECU which I intend to swap into an 84 Chevy. The engine was nearly new but it came without a wiring harness or ecu. I bought a used ecu and wiring harness and have wired everything up. I have it set up on a run stand, and have wired in the following pins outs from the ecu.

Pin 2 ground
Pin 3 fused 12v
Pin 4 ground
Pin 5 fused 12v
Pin 6 ground
Pin 18 can low
Pin 35 can high
Pin 70 key on 12v
Pin 71 key on 12v

I connected fuel, accelerator pedal is not yet hooked up. After cranking the engine fires and runs for about 3 seconds then dies.

Any idea what I need to do to get it to idle/run continuously? Could this be caused by an ecu skim? Do I need to reflash the ecu? Any ideas are most welcome.

I'd like to get it running well on the run stand before swapping it in. There are no vehicle electronics to think about, I just need the engine to run.

Thanks!

What’s up brother
Did you get that engine running?