Johnson 1985 110 HP Tach issues

[oreo1]

I have a 1985 Johnson 110 HP outboard and I am replacing the tach on the dash. I checked the switch on the back of the tach to make certain that it was set correctly and I am still not getting anything at all. I double checked the obvious, all wires connected the same as the old ones, rusted connections, frayed wires, etc., and nothing.
I need to trace it back to the distributor/points next to make certain that wire is also good. Does anyone have any advice on doing this or any other possible trouble shooting pointers that I could use to get this frustrating issue solved?
As always, thank you in advance for any help or information you would like to share!!

 

[ondarvr]

Re: Johnson 1985 110 HP Tach issues

We might need some more info to get you a good answer.

What do you mean by "not getting anything at all" ?

Did it just stop working, has it ever worked since you've owned it?

You don't have points or a distributor, its an electronic ignition.

One of the main causes of no reading on the tach is a bad rectifier.

 

[emdsapmgr]

Re: Johnson 1985 110 HP Tach issues

They did not make a 110 in 85. Likely the engine is a later model, perhaps an 86. As was mentioned, the tach is driven by the rectifier/regulator, mounted at the top of the rear block, under the flywheel. That component does two things: it is responsible to recharge the battery and it sends pulse counts to the tach. If your tach is inop, likely it is bad. When it does go bad, usually the recharging of the battery also quits, so you can check the battey voltage to double check it. If the voltage never gets above normal battery voltage (12.4-12.6) after running for a while-probably need to replace it. If the voltage creeps up to 13.5 or slightly higher, it is probably ok and you should look elsewhere for the problem.