1986 175 HP Johnson Charging Problem

[111torrance111]

I recently had to replace the Stator on my 1986 175 Johnson motor, one of the magnets came loose and bent everything up. I bought a used stator & installed new magnets and reassembled. Motor works & runs great but now the charging system isn't working, it was fine prior to this repair.

I'd like to learn how to test everything in the charging system, any help on what to check first and in what order would be appreciated.

Thanks/Jerry
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[emdsapmgr]

Is the tach on the boat working? The stator produces both ignition voltage and (separately) produces battery charging voltage. Two different sets of coils. The charging voltage goes thru the combination rectifier/regulator on it way to both the battery and the dash tach. It's the water cooled electrical device that sits between the two cyl banks just under the flywheel. Usually, when you have charging issues, you will find the tach is acting up since they both function off the combination rectifier/regulator. It is part number 0395204. You've got a high-capacity 35 amp alternator, so it pays to resolve this charging issue quickly, as the current can generate heat if it's not dissipated as designed.

 

[111torrance111]

I took the boat out today, the Tach was working but did act up a few times. I knew I was running around 1,000RPM & the tach would randomly go to zero or jump to 5,000 rpm. It seem to do this while under power, when idling the tach seemed stable.

Does this point to something specific?

Jerry

 

[boobie]

Run it with a volt meter across the battery and see what kind of voltage you get at WOT.

 

[emdsapmgr]

Failing rectifier/regulators cause all sorts of tach problems-including what you are experiencing. Each different. Likely the battery is not being recharged properly. Follow boobie's suggestion. The battery voltage should be normally around 12.5 or 12.6 volts. After running for 15 minutes, the battery voltage should increase to close to 13.5, indicating the charging system is working normally.