The fact that the motor has worked already with this ECU and loom still makes me think there is a fundamental wiring issue - probably with power feed.
Strangely enough, I always would listen for the reassuring 'prime' of the fuel pump on switch-on. It stops after a few secs - the actual delay being programmable in the ECU setup..
However, I installed and configured a new M48Pro a couple of weeks ago, and no prime on switch on....hmmmm... starts the split second you crank, motor runs fine and if you kill the motor, the pump runs on for a couple of secs as expected, but the lack of power on prime is new to me... I'll have a look at the ECU config as maybe it's optional now with the latest rev of firmware. Also - the wetting of the manifold Ross describes when full throttle is applied with motor staionary but ign on, 'might' not always occur as it too can be disabled in the software. Of course the ECU that mcpete is using is an M800 which uses much later software, but by all accounts is even more flexible in what it can offer, plus it does have very comprehensive diagnostics/monitoring/testing features so a laptop under the circumstances is essential as Ross says.