Lost power to 30HP 4 stroke 6BET yamaha outboard

[Stessl4324]

I have removed the under floor tank replacing it with a plastic tank. with disconnecting the fuel gauge can not get power. Only found 3 fuse (1) main switch/trim switch. (2) Rec/reg ecm fuel injector vsv, (3) starter relay. can some one advise if any more as I can't find them also had power before removing tank also i have had the gauges out.

Stessl

[boscoe99]

What is the complete engine ID? Or year?

[99yam40]

do you have a voltmeter to check to see where you have 12V power and where you do not?
what works and what does not work?