1978 mercury wiring harness adapter to new 8pin controls

[Donnyb83]

Hey I have a 1978 mercury 800 80 hp. The wiring harness is an old 6pin side cowling. I just bought a new 8 pin to 6 pin wiring harness adapter (part number 421-4401) and new mercury boat controls. I hooked up the controls and started the boat. I couldn’t get the boat to shut off until unhooking the fuel line. Any idea why this would happen? Finally after almost two thousand dollars I got the boat to run great and now this! I’m at the end of my ropes.

 

[Chris1956]

That motor has 4 ignition coils, right? Make sure your keyswitch grounds the salmon or orange wire (original wire color), or the black/yellow wire (newer wire color). That wire should connect to the switchbox, to kill the ignition.

 

[Donnyb83]

Ok I’ll check sometime this weekend,and see what I come up with thanks