Johnson 90hp Will Not Turn Off

[Miroash]

I have a 1986 90hp Johnson that I just repowered my boat with. i purchased it used from a guy, he started it and it ran ok, and then he turned it off (by the ignition switch). I just put it on my boat and started it just fine, ran good with no problems, except when I went to turn it off, it will not turn off. I disconnected the battery, still runs, so i finally disconnected the fuel line and waited for it run out of fuel. anyone know which wire kills the motor on this engine so I can verify it is connected correctly? I have a manual but it is kind of hard to decipher, it looks like everything is as it should be.

 

[Barnacle_Bill]

Re: Johnson 90hp Will Not Turn Off

Never disconnect the battery while the motor is running. There is a good chance you blew your rectifier and or regulator when you did that. There is a black/yellow wire that runs from the power pack to the ignition switch. This wire is grounded when you turn the motor off.

 

[Miroash]

Re: Johnson 90hp Will Not Turn Off

do you know which pole it should be attached to on the ignition switch?

 

[Zeeter]

Re: Johnson 90hp Will Not Turn Off

Check that big red plug under the hood. You can bet you popped the rectifier.

 

[Miroash]

Re: Johnson 90hp Will Not Turn Off

Check that big red plug under the hood. You can bet you popped the rectifier.

do you mean the red cable/harness plug or a different plug?

 

[Miroash]

Re: Johnson 90hp Will Not Turn Off

Never disconnect the battery while the motor is running. There is a good chance you blew your rectifier and or regulator when you did that.

My parts list shows 2 rectifiers, which one is the one that will most likely be blown, the little silver cylinder shaped one or the big square one? and how do I verify its bad? thanks

 

[bustermin]

Re: Johnson 90hp Will Not Turn Off

do you know which pole it should be attached to on the ignition switch?

I believe there are 2 poles labeled "M", one of them is vertical, and the other is horizontal, depending on the ignition switch you have. The horizontal one is where your ground wire is attached; the vertical one is where the "Kill" wire goes. as far as how to test to see if you blew the rectifier/regulator, I suppose the easiest way would be to check the battery with the motor off, and then again with the motor running. You should have a higher reading with it running. Maybe somebody can verify this or correct me if I am wrong on any of this. If it's bad I feel for you, that is a costly learning experience for you, I think a new rectifier/regulator is like $200+

 

[Miroash]

Re: Johnson 90hp Will Not Turn Off

that is a costly learning experience for you, I think a new rectifier/regulator is like $200+

Yea it sure is, not to mention last night my wife smoked the impelleron our other boat. so now both boats are down. I really hope the rectifier didnt blow, but Im not holding my breath, more than likely it did. Thanks

 

[red10]

Re: Johnson 90hp Will Not Turn Off

what Bustermin said, that is the easiest way to see if its fried, should be around 14V at 1000 rpm. Reg/Rectifier is $240 and it sounds as if one of the power packs kill wire or circuit is bad, had the same problem, just see which bank it is ( assuming this has 2 packs ) and disconnect the wire Black/yellow and see if it shuts off.

 

[Lion hunter]

Re: Johnson 90hp Will Not Turn Off

Actually both things you did were completly wrong and could have severely damaged your motor. Never unhook your battery while running or hook it up backwards, it will fry your rectifier or power pack. Never run a multi carb motor out of fuel. The carbs do not run out at the same time so you are running one cylinder bank without lubrication until it runs out of fuel. If it wont shut off you choke it and let it die. Good luck but it sounds expensive.


if you have spark but no charging you fried the rectifier.

no spark=fried power pack

 

[wilde1j]

Re: Johnson 90hp Will Not Turn Off

Guaranteed the rectifier is toast ...

 

[bustermin]

Re: Johnson 90hp Will Not Turn Off

LOL!! You guys should stop sugar coating this, whats the bad news? lol

 

[Miroash]

Re: Johnson 90hp Will Not Turn Off

Guaranteed the rectifier is toast ...

WOW!!!! Man did I dodge a bullet, got home and checked the voltage. When the motor is off I have 12.7 volt, when it's running I have 14.3 volts!!!

 

[Lion hunter]

Re: Johnson 90hp Will Not Turn Off

Great news! Make sure not to do it again. Can't get that lucky twice.

 

[daselbee]

Re: Johnson 90hp Will Not Turn Off

Never disconnect the battery while the motor is running. There is a good chance you blew your rectifier and or regulator when you did that.

My parts list shows 2 rectifiers, which one is the one that will most likely be blown, the little silver cylinder shaped one or the big square one? and how do I verify its bad? thanks

You only have one, depending on whether your motor has PT&T. But I am glad you did not damage it.

The black/yellow wire is the kill circuit. You will ground it when testing to check for proper operation. Ground it at the terminal strip of the engine. If the engine kills, you have an open in the black/yellow wire from the terminal strip to the key switch somewhere.

 

[Miroash]

Re: Johnson 90hp Will Not Turn Off

The black/yellow wire is the kill circuit. You will ground it when testing to check for proper operation. Ground it at the terminal strip of the engine. If the engine kills, you have an open in the black/yellow wire from the terminal strip to the key switch somewhere.

That is what I did, turns out I had a bad ignition switch. I happen to have a spare from my old boat that I parted out, so problem solved. Thanks for everyones help, and most of all THANK GOD the rectifier is ok!

 

[bustermin]

Re: Johnson 90hp Will Not Turn Off

That is what I did, turns out I had a bad ignition switch. I happen to have a spare from my old boat that I parted out, so problem solved. Thanks for everyones help, and most of all THANK GOD the rectifier is ok!

That's good news! at least now you have one working boat. now all you have to do is repair your wifes impeller and the fleet will be up and running!! good luck!

 

[arnettjs]

Re: Johnson 90hp Will Not Turn Off

"The carbs do not run out at the same time so you are running one cylinder bank without lubrication until it runs out of fuel."

Thank you, that is actually a very good point. I have a '92 Johnson 115 and usually let the carbs run out of fuel. The intent is the obvious, keeping the carbs from getting gummed up. You are 100% accurate in that they don't run out at the same time.....great point!

 

[Miroash]

Re: Johnson 90hp Will Not Turn Off

If it wont shut off you choke it and let it die.

FYI, I can not choke it to get it to shut down. My engine has a primer, not a typical choke. I tried to push in the key to choke it down but all that did was give it more fuel, and rev the motor. that is why I disconnected the fuel line and let it run out, I did not have any other options. i suppose I could have removed the silencer and put a rag or somthing over the carbs, but Im not crazy about taking a running engine apart.

 

[Lion hunter]

Re: Johnson 90hp Will Not Turn Off

Maybe someone else will chime in. Would seem there would be a safe way to kill the motor if you had to.