115 hp Engine stalls after it cools

midtvedt

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Sep 26, 2005
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My recently purchased 1998 Johnson 115 has problems starting and idling - particularly in gear at idle speed - after it has been run and then stopped for 5+ minutes. My mechanic is scratching his head - the coils have been changed, the carbs have been soaked... This appears to be a common problem - reference the posting "Hot start problem on 2003 Johnson 150"<br /><br />Have any Johnson Mechanics out there seen service bulletins addressing this problem?<br />Thanks for reading!
 

Marc J.

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Mar 16, 2004
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Re: 115 hp Engine stalls after it cools

Others and myself have had similiar problems with our slightly older v4s. Ask your guy if he's confident that the floats are set correctly? Someone suggested that a too high float setting could be causing flooding. My engines respond to additional fuel so I doubt that is my problem. Try a spark check while holding a hairdryer near the powerpack and coils. Also, look for poor ground connections. Good luck with it.
 

midtvedt

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Re: 115 hp Engine stalls after it cools

73BAJA - Thanks for the suggestion<br /><br />Mike from Charleston (Mt.pleasant) SC
 

Joe Reeves

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Re: 115 hp Engine stalls after it cools

When the engine is running, flywheel spinning, air flowing thru/under the hood etc, there's a certain amount of cooling being vented.<br /><br />However, when the engine is shut down, water's being drained out of the powerhead, all of that heat is now trapped to a certain extent and is flowing upwards towards the flywheel and its related components..... the stator being one of them.<br /><br />The stator generates power to charge the battery via its smaller coils within the stator, but there are two large coils also within the stator that generate approximately 300v AC to energize the powerpack.<br /><br />A failing stator, when cool may generate that needed voltage, but will suffer a voltage drop when hot. Usually if this is the cause of the problem, the stator can be checked visually and will normally have cracks and or be dripping a sticky substance down on the timer base nylon bearing ring and the top of the powerhead.<br /><br />This may not be your problem but it's something that I would look for first.
 

midtvedt

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Re: 115 hp Engine stalls after it cools

Thank you Joe - One day as I was paddling the boat to the trailer, after it stalled on approach, a bystander told me that his friends new 4-stroke would not idle under 2/k and it turned out to be an electrical component in the engine...
 

Solittle

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Re: 115 hp Engine stalls after it cools

Another possibility is missing thermostats. Those motors do not idle especially well unless up to operating temp. A lot of guys will remove the thermostats thinking cooler is better. Not so - - - -
 

midtvedt

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Re: 115 hp Engine stalls after it cools

Thank you sir - I will add that to the trouble shooting list - much appreciated!
 

Marc J.

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Mar 16, 2004
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Re: 115 hp Engine stalls after it cools

Hey Midvet, I moved the primer bulb to right at the motor. It stays in a vertical position and restarts much better now. It sounds kinda basic and it may not be your problem, but I thought I'd pass it along.
 

midtvedt

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Re: 115 hp Engine stalls after it cools

Crossflow Collector? - Interesting AKA... Can you explain that moving the primer bulb move to me again?
 

Marc J.

Petty Officer 1st Class
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Mar 16, 2004
Messages
267
Re: 115 hp Engine stalls after it cools

Moving it may be unnecessary. The primer bulb should be in a near vertical position and the internal check valve needs to hold. It may not be your problem. But, after a thorough decarb and relocating the primer bulb, my 90hp restarts perfectly.
 

Seasport

Chief Petty Officer
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May 2, 2005
Messages
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Re: 115 hp Engine stalls after it cools

Interesting. I've heard this before. I guess the non-return valve needs a bit of help from gravity. Perhaps what is happening is that when the primer bulb is horizontal you get some reverse fuel flow. This combined with a warm engine causes vapour lock in the fuel lines and hence difficult starting from warm.<br /><br />Does this sound plausible?
 

midtvedt

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Sep 26, 2005
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Re: 115 hp Engine stalls after it cools

Thank you very much - That is certainly worth a shot - are you interested in a (boat) working vacation in Charleston...
 
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