20hp '98 Johnson Fouling Plug, maybe primer.

Gamehunter56474

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Aug 2, 2012
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Bought a pontoon with 1998 20 hp Johnson, Started and ran perfect. Had a power surge. Replaced the 20amp fuse in the red inline holder on the side of the motor. Got power back, started right up ran good until I throttled it up than it started missing a little and there was unused gas coming out of the water from the exhaust. Found the top plug only fouled.
Replaced plugs and cleared the cylinder same thing, started instantly ran good till reved than fouled top cylinder. When I push the key in for the choke i hear nothing, I think i used to hear it click. I found out that it may just be a primer instead of an electric choke??? Also the red lever on the primer/choke is pointed toward the throttle body. If the primer is fried would it stay open or closed to cause flooding? Where do i go from here?
 

Daviet

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Sep 24, 2008
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8,958
Re: 20hp '98 Johnson Fouling Plug, maybe primer.

Doesn't your fuel pump mount to the top exhaust cover? Maybe you have a defective fuel pump diaphram allowing fuel into the cylinder at high rpm and flooding it. The primer solenoid should click when the key is pushed in. The red lever should be turned back over the solenoid body. The primer is in the closed position until you push the key in, usually they don't bypass fuel if defective.
 

Gamehunter56474

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Joined
Aug 2, 2012
Messages
3
Re: 20hp '98 Johnson Fouling Plug, maybe primer.

I don't know what the fuel pump looks like. I can follow the fuel line tomorrow and see if it is. Would the fuel pump diaphram be effected by the power surge, because the problems started right after we got power back. Is there another fuse I'm not seeing, in the controls or in the motor.
 

Daviet

Fleet Admiral
Joined
Sep 24, 2008
Messages
8,958
Re: 20hp '98 Johnson Fouling Plug, maybe primer.

Electrical power surge will not affect the fuel pump. Exactly what do you mean by a power surge, did you have a short somewhere that blew the fuse? A fuel pump with a defective diaphram can be affected by engine rpm. The higher the rpm the fasted the diaphram moves.
Here is a picture of your fuel pump.
http://www.ishopmarine.com/ishop/js...CatFilter=BRP&eCatSupFldr=supplier-100-005-EJ
Here is the fuse for your engine.
http://www.ishopmarine.com/ishop/js...nown&isFrPG=false&forItemCode=&pCode=C0072155
 
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