Johnson 120 V4 Shuts Off

sport300zx

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Apr 4, 2007
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12
i have a 1989 johnson 120 V4 Vro.......So im driving across the lake when my engine just shuts off. (no sputtering or anything) SO i try to start it, motor turns but no spark.. SO the next morning i go outside and it starts right up. Found a messed up spark wire that may have arked on egine. so replaced them all. so i go out again and im cruising same thing motor shuts off at half throttle and wont start back up, and again the next day it starts right up...could there be a short tripping the relay or breaker i dont know a lot about this engine, please help:'(
 

stewart

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Mar 20, 2007
Messages
28
Re: Johnson 120 V4 Shuts Off

just a thought...could it be that the engine is shut down by the temperature sensor circuit to prevent over heating? I would check to make sure that it is getting proper cooling.
 

ezeke

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Sep 19, 2003
Messages
12,532
Re: Johnson 120 V4 Shuts Off

The only thing that should shut your looper down that way is a short to ground in the black and yellow kill wire leading from the control's ignition switch and the emergency kill switch to the power pack.

In order of probability: [1] emergency kill switch is loosing tension; [2] bad ignition switch wiring or ignition switch is going bad; [3] internal short in the wiring harness going to the engine.

You have S.L.O.W., so if it were overheating the power pack would drop you down to 3,000 or so, but it would not stop the engine cold.

 

sport300zx

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Apr 4, 2007
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Re: Johnson 120 V4 Shuts Off

So i took it up to the boat shop and they say they fixed it, some loose wiring under the dash, they said it ran fine for them and they couldnt get it to shut off by itself anymore, i guess i wont really know until i take it out on the water again, thanks everyone
 

tashasdaddy

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Nov 11, 2005
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51,019
Re: Johnson 120 V4 Shuts Off

yep, that could do it, loose wire on kill circuit grounding.
 

ezeke

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Sep 19, 2003
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Re: Johnson 120 V4 Shuts Off

Damn! I thought that was what I said. Must be loosing it.:cool:
 

sport300zx

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Joined
Apr 4, 2007
Messages
12
Re: Johnson 120 V4 Shuts Off

i guess they didnt fix it, i went out today and once again when i started to demand more power the motor started to shut off, and it sputtered out, and wouldnt start back up, so i shut off all the power and when i got home the motor cracnked right up.
 
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