50 hp Johnson Outboard - Engine cuts off after running wide open

DirtMcGirt

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Nov 26, 2012
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50 hp Johnson Outboard - Engine cuts off after running wide open for about 20 seconds. Both carbs have been taken apart and cleaned thoroughly. Idles well and runs good at lower rms. Tried adjusti.ng while on water and it does not seem to make a difference.

Background: Motor was taken froma non running state(sat for a year or two). Now it starts up and sounds like it is running solid... But when you accelerate it eventually just cuts off. It will start again aftr about 5 minutes or so, but then does the same thing over again.

Any ideas??
 

huntingtheworld

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Jun 13, 2010
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Re: 50 hp Johnson Outboard - Engine cuts off after running wide open

Sounds about like my boat.Check to see if the plugs are fouled.
 

DirtMcGirt

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Re: 50 hp Johnson Outboard - Engine cuts off after running wide open

Just to add more notes... I have cleaned carbs(even high speed jet in bottom of bowl as other posts have suggested) and replaced plugs.
 

pn

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Apr 20, 2013
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Re: 50 hp Johnson Outboard - Engine cuts off after running wide open

others have noted that coils tend to loose spark after warming up. i really hope your not running lean you'll kill your motor in 6 secs
 

Solittle

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Re: 50 hp Johnson Outboard - Engine cuts off after running wide open

Could be several things - Start by squeezing the primer bulb as it starts to stumble. If it picks up you have a fuel problem - might be air leak in the fuel line, clogged vent at the tank etc.
 

DirtMcGirt

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Re: 50 hp Johnson Outboard - Engine cuts off after running wide open

Thanks for your responses. I plan to spend some time working on it tomorrow and troubleshooting.

PN: What is the easiest way to check the coils to see if they lose spark? I have a basic inline spark tester, but not sure it will work for that.

Solittle: Ill keep the primer bulb in mind next time in on the water. There is what appears to be a separate line coming off the tank that comes up and out by the transom.... It has a cap on it and it appears to have a screen/filter. Would that be vent and should cap be off of it? I have tried with and without the cap on.

For some reason I want to say its getting flooded bc motor wont start again for about 5 minutes... But not sure... Just seems weird to work so well at lower rpms... But once i run hard for awhile it just dies.

I plan to check and blow out fuel lines tomorrow and check some other basic stuff.

Just curios... If the fuel pump was bad... Would it do something like this?

Thanks again for your thoughts. Im stumped at the moment on this one.
 

DirtMcGirt

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Nov 26, 2012
Messages
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Re: 50 hp Johnson Outboard - Engine cuts off after running wide open

Just did a compreson test. Top cylinder is 100 psi... And the bottom cylinder is at 150 psi. It is a Johnsonn 50 hp two stroke. Would this relate to issue?
 
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