Your s/n comes up as :
MERCURY - ( 90 H.P. (1995 ))
Serial No: 0G255654 Model No: 1090412RD
Parts List for model 1090412RD:
75/90 HP 65 JET (3 CYLINDER) - Mercury, Mercruiser, Force, etc. Parts Lookup
If you send me a PM with an email address, I can send you a copy of the service manual which contains the wiring diagrams.
Gerry