1991 15HP Johnson Problem

dew2

Senior Chief Petty Officer
Joined
May 6, 2010
Messages
674
The motor starts easily,runs great at idle,Problem is when going full throttle it sometimes just bogs down and only runs 1/2-1/3 power/speed.The carb has been cleaned and kited,The fuel lines from inlet to pump have been replaced with new the fuel line from pump to carb also new.I have tried a fuel line that off another 15 that runs great also tried that fuel tank. When I give it full throttle it may take off BUT It may not.Got me stumped??
 

AlTn

Commander
Joined
Mar 9, 2010
Messages
2,813
Re: 1991 15HP Johnson Problem

are you possibly losing spark to 1 cylinder?...you can check easily with an inductive timing light...the gremlins in that ufi ignition system can cause those types of problems
 

boobie

Supreme Mariner
Joined
Nov 5, 2009
Messages
20,826
Re: 1991 15HP Johnson Problem

Pull one spark plug wire at a time with an insulated pliers when it happens and see if you have a dead cyl.
 

dew2

Senior Chief Petty Officer
Joined
May 6, 2010
Messages
674
Re: 1991 15HP Johnson Problem

Thanks for the replies!! I got held up and will be asking again at a later date.Need a neck surgery sooner than expected.Get er done!
 
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