Possible ECU problem? Car won't crank on one ECU.
 

These past 3 days have been packed with intensive engine swapage. I bought a salvaged title 05 Revup with a stillen supercharger and tons of other stuff done to it. Also, I bought a clean title 03 shell. I've done the entire engine swap, but I have some issues with fuel. The ECU I took out of the 05 seems to not push any fuel when cranking. The fuel pump does prime just fine though. As soon as I swap to the 03 ECU though it starts up just fine. I took the 05 engine harness and everything from the other car.. I couldn't find anything about this specific issue. I've heard programming keys to the other ECU. Is that what I need to do to fix this issue?

The key needs maped to the ecu or NATS won't allow it to start. I'm not sure if it kills fuel or spark but it wont allow it to start.

You need to reflash the ECU with Uprev and disable NATS. PM me if you have any specific questions

As said - apparently you can disable the nats with uprev,