There’s a white wire coming from the external harness to the mercury switches also, I’m assuming that just goes to 12v constant power?
NO, please don’t connect that white lead to 12V positive…That lead provides a ground from the mercury switches to the negative post on the solenoid…That mercury switch prevents the engine from being started at too high of a throttle setting by opening the ground connection when the throttle is set up too high…
The engine will start without any of this stuff being connected, it just won’t shut off and might over rev if the throttle is set up too high in neutral or you cut the throttle back quickly.
I would check over the rest of the engine before getting too involved with this wiring. No sense going crazy finding a wiring harness if the engine has low compression, water in the gearcase, ignition and fuel system issues…
