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help with a johnson 90 hp outboard

Z

zpmontog0947

New member
Hello i have got a 90 hp outboard motor but it has a 115 power head on it it is from 1989 rebuilt like 5 years ago. all last year we were having problems with the battery not being recharged. and today i finally had some time to look at it and i could not figure out exactly how the alternator system works, i was thinking something on the flywheel passes by a coil on the block or something and generates the electricity. im pretty mechanical and i want to fix it on my own but really could use some help. i tested the voltage at the battery before i started the motor and it would be at 12.5 volts, then i would check the battery after the motor was started and was revved pretty high and the voltage did not move anywhere on the meter, so im pretty sure there is nothing coming back to the battery? right? i am strapped for cash so i would really like to solve this on my own, what do u guys think? how does this thing work and what do u guys think is going on? where do i
 
I am no help on outboards but checking the volts is not helping you it will always read 12. You need to check the amps going in to the battery when its running.
 
and what kind of amps should i be getting at the battery when it is on and off, i started it, disconnected the leads from the battery terminals and measured the voltage from the motor completely disconnected from the battery, and it measured 12.5 volts when the motor was revving pretty high, so im guessing somewhere in my boat, im draining the battery, maybe with the radio or something, or is current the end all be all decider if the alternator is good or bad?
 
The best advice I can give you is to look on ebay for a Johnson service manual. They can be had for cheap. It will give you step by step procedures and principle of operation. It sound like your rectifier/regulator may be bad. This part is the first to go if there is a short or the battery cables are removed with the engine running.
 
If your still having problems PLEASE call me day or night at 920-295-2069 or Tuesdays thru Saturday 9am (central time) to 5pm at 920-787-5873 I run a Marina in Southern Central Wisconsin and ALWAYS Hook up my bros here and on Scream and Fly...I have 1 of the best OMC techs in the state, and especially on the older stuff...Thats why I bought 1 of the best motors in the Business, a OMC V4, mine is a 1982 Crossflow 140, I have Plenty of OMC parts some even used......call me anytime....Brannon MARKSQUALITYMARINE.COM
 
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