Tacho problems

[TwoFish]

I am having trouble with a tacho on a 1998, 75 force outboard. It keeps reading high from only a couple of hundred revs to about a thousand. The engine noise doesn?t change but the tacho can just start reading high. I have checked the connections on the back of the tacho and also the connection in the loom by the throttle control.

The boat is stored under a tarp & moisture builds up at times as a result.

Not sure what to look at next.

I could try to find another tacho but I would like to know if anyone has any other ideas.

 

[SweeperForce]

Re: Tacho problems

This may be a long shot, but try connecting your tach signal wire to a different AC wire. You should have two wires that come from under the flywheel both the same color. Those two wires run into your rectifier/ voltage regulator. Those two wires are know as the AC wires, because they put out about 25 volts ac. The rectifer turns it into dc. It is my understanding that if your tach does infact work,and your needle is jumping all over the place, just switch to a different ac wire. Sorry if this post seems elementary, but I didn't want to let anything out or be vague.
My ac wires are green w/ yellow stripe see picture below.



Tom

 

[TwoFish]

Re: Tacho problems

Thanks Sweeperforce,

I?m new to repairing outboards so nothing?s too basic. I read through some other posts on electrical problems with force outboards. So with the combination of your advice and what I found in the forum I managed to trace the problem to a corroded wire in the main loom on the back of the engine. I took the boat out today and everything worked fine.

This forum is just a goldmine of information offered by some very generous people.

Thanks