Mid 80s mercury 115hp electronic problem.

[Whistler123]

Hello folks.

Judy getting until this whole boating thing. Picked up a 16' ski boat with the Merc 115hp 2 stroke tower of power.

Anyway things were going great on the restore, came to idle the engine on muffs it almost started then died with a crack.

Lost power to the trim and unable to start. Occasionally I would get a little click when I tried to do either. Nothing else.

Started looking round the wires for anything obscure couldn't find anything.

Can pick up on the multimeter 12.8 volts following the red wire in a little way. I dont know the wiring plan.

I changed the 20amp fuse to be sure.

I decided to see if I could jump it from my car battery. To my surprise I got a little movement of the trim and it almost turned over but then completely died and went back to doing nothing.

Is this ringing any bells for anyone where I should concentrate my efforts. Cleaning terminals etc

Any help would be appreciated I'd love to go boating for the first time in my life.

Thanks gang

 

[Whistler123]

Cleaned a few contacts got it working briefly and smoking at the terminals, I'm assuming bad earth and corroded contacts.

It always had problems starting though. Could it be the starter? I don't know how that would stop the trim

 

[Chris1956]

You are correct, the trim would not be affected by the starter. Everything you describe can be explained by dirty/bad wiring.

The engine wiring harnesses get pretty bad (corroded, insulation falling off) by this time. Does the motor have a distributor ignition or 6 coils?

Also, the quick disconnect plug on the starboard side can get pretty corroded. Corrosion can be under the good insulation on the battery cables. Look for bulges in the battery cables. Clean everything up and retest.