New ECM, engine won’t start.. calibration?

[Majr808]

I put in a new Mefi 4 (4B) ECM from Marine power into my 5.7 MP 340hp… trying to fix a surging rev issue.

The engine won’t start at all now.. never had this issue with the previous ECM.

Is there some type of sync I need to do with the key? Marine power said they programmed it for my engine. It feels like the timing is off… spark is there, fuel pressure is good. Batteries new and charged.

If I crank it enough it will start to catch and may run for 1-3 seconds but dies pretty quick.

[25cents]

If you swap back to the old ECM will it start? I would start there and if it won’t start still them you know it’s not your ECM

[Majr808]

I sent my old ECM to marine power for them to diagnose so I don’t have it anymore… but just days ago it was starting with no hesitation with the previous ECM. This is a new problem and only started when the new ECM was thrown in. Wish I had the old one still to verify.