Take a look at my pic I have attached. The wiring should either be the same or very similar - White wire for ignition (12v), Salmon/reddish wire for send (signal), and black for ground. Hope this helps!
Older mercs used the brown wire for tach signal. Newer mercs use the grey wire for Tach signal. Salmon wire was ign killer for ADI igntion, on the older Mercs. What year is your motor?
