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Diagnosing a Bad Stator

Mikebones1111

New member
Hello I have a 1986 140hp Johnson V4 (VRO removed)

My charging system seems to be weak when motor is running the volt gauge sits at 12v and that is confirmed by multimeter. I talked to a Power sports mechanic he asked me some questions if I had any melted plastic dripping from the stator windings which I do not as far as I can tell. He then recommended I try replacing the regulator/rectifier before replacing the stator. He said the previous owner could have fried it by jumping it from a running car. I replaced it and I saw only a slight gain in the voltage 12.5-13V when running not the 14+v I think I should be getting (If someone could confirm that because that is just a guess).

I am mechanically inclined and do most of my own work but another mechanic friend said it might be easier to pay to have the stator replaced. Has any one replaced their stator would you recommend doing it yourself again or paying to have it done. Can I check anything else to see if it solves the problem before diving into the stator?

Thank you,
 
If your motor is like my87 150hp then you re not going to get a high voltage reading but you can go to CDI Electronics.com and get instructions on testing your motor. Good luck.
 
Hm this sounds familiar....my old 1975 135hp wouldnt read above 12.5 at any rpm because the voltage regulator was ...get this ...regulating the voltage. Weird huh. Not familiar with your motor but if theres any way to disconnect the voltage regulator only and run it to 2000rpm. Then your voltage should be getting up there where you think it should be. Yours may be a rectifier/regulator in one then you wouldnt be able to do this.
 
Voltage was checked on the barrel so no WOT. When I launched it and ran it at 4.5k it worked its way up to 14 volts after 15 mins of run time at that rpm on the volt gauge that was not confirmed with a meter however. Sorry that may have been important to note in the original post
 
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Any time you change a stator it is recommended to replace the regulator at the same time....CDI says 173-3668 for the stator and 193-5204 for the regulator. I believe you can use that flywheel but it was the V-6 motors that came with the 35 amp system.

I put a new CDI
193-4205
reg on last year, it is rated 10a. So I think I would have to upgrade??? if I were to do the 35a stator upgrade from the stock 9a
 
''When I launched it and ran it at 4.5k it worked its way up to 14 volts after 15 mins of run time at that rpm on the volt gauge''
Was that battery fully charged when you put the boat in the water?Try it with a fully charged battery or better yet try it with another battery that is fully charged..if the battery is sucking up amps then the voltage would read low on some charging systems..especially if you have an additional load on the battery...
 
Are you running your appliances directly off the battery? Is everything fused?

Everything is behind battery switch and is fused except bilge pump is directly wired to battery adding an inline fuse would probably be a best practice for that I will add it to the list this spring.

I don't want to make a mountain out of a mole hill here but I have been aggressively researching the 35a stator conversion I believe I can make it happen for $450 in a new stator and regulator which may be worth it for me if can determine the charging system isn't providing enough power Which is now what I am thinking is the problem. I run an on demand wash down pump and an HDS Gen-2 w/Side scan module. That coupled with my tendency to short drift where I constantly start, run and stop is very demanding. I also have a battery maintainer w/PV cell on the boat when it is moored.

Sometimes I feel like I'm playing darts trying to solve this problem. Sometimes I wish is wasn't such a Fishing NUT!

"Bust Out Another Thousand"
 
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you may need a new flywheel also...not sure about it but i think the magnets you have are not big enough to do the job..if you have an aluminum flywheel you probably will be changing to steel..also expect to lose about 5 hp on the engine due to resistance caused by the magnet/coil increase....
 
The 35 amp alternator kit for your motor is part number 174330. Marine engine says it is no longer available. But you can see the parts required here on marineengine. Look under the 1986 Evinrude accessories listings. You DO have to change the flywheel, an $800+ item.
Also the crankcase head and bearing assembly, another $200 item. Still interested??
 
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You DO have to change the flywheel, an $800+ item.
Still interested??
Now this changes my perspective... Not worth putting $800 into an almost 30 yr old motor. I still don't understand why the current flywheel won't work. Magnets not sufficient?
 
Vro removed the research I have done said to get rid of them in that model year. Low oil alarm was unreliable that is the only way johnson could kill them otherwise it's a workhorse.
 
True on different magnets...i keep getting back to the statement that it puts out 14 volts after its been run for a period of time...something is sucking up current to keep the output that low for more than a couple minutes...and the only thing that would draw less current after running is the battery..it could be low output from the charging system but thats not what i would address first..

i would go with 2 batteries ..get everything off the ignition battery but the bilge pump...if you have a rectifier only system you do not want to run a maintenance free battery on the ignition...get the kind you add water to..a maintenance free battery will take out the rectifier sooner or later..a good ignition battery will give you more starts in a day than you will ever need if the engine is in good shape even without charging...
 
0ne note...if after making a long run(30 min or so) you still see only 14 volts that is a little low from my experience...on a regulator system you should see 14.8 volts..on the rectifier only system the voltage should creep up higher than this...if it dont measure the voltage at the output on the motor...there should be a terminal block there...you may have a bad connection somewhere dropping the voltage...
 
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