Hi team, I am progressing with putting the Y33 Cima engine into my boat (a 30 foot launch with a sterndrive).

Essentially, it will be running a stripped out factory ECU for management.

I have power to the ECCS and relays, they click nicely on powerup.

However, she wont start or fire so I am thinking I need to identify the START SIGNAL wire.
Every diagram so far has a different option, and the closest I have (Q45 vh41de diagram) points to an empty pin 80.

Can someone help out - I think this is the last element to get her started and running!

Have you looked at the diagrams in the FSMs at infinitiservicemanual.com ?

I have mate - the Q45 harness is different.
For example it quotes pin 80 as start signal yet my pin 80 is empty.