87 Johnson 50 (3 cylinder) bucking and kicking

[Mooser66]

Hi all, long time boater, first time poster
I've had this engine since new and never had any issues until this season

First day out it worked flawlessly

Second day out, after about 5 minutes on plane it started stumbling and the rpm's dropped, went down to idle and it seems fine, idle up and it was ok, then started to kick again, found it's ok around 1500-2000 but any higher and it would start to "buck" heavily, looking at the motor it's actually kicking. Turning it off and fished a little, then started it and anything just over idle seems to start kicking, started limping home and after a few minutes tried throttle up and it worked ok al the way home.

Today went out and for about a 30 minute run worked fine, then started the same routine, buck and kick when throttling up, first around 3000rpm then kept getting worse until it kicked at 1500 rpm, tried pulling one plug at a time and it would rev up (no power of course) no matter what cylinder was disconnected, with all three buck buck buck. Limped half way home, fished a bit tried having my buddy keep squeezing the bulb (it would go soft) and at first that seemed to help but then didn't matter.
Part way home it seemed to smooth out a bit and I throttled up and it ran all the way back....

Don't even know where to start...
Mooser66

 

[TDmanager]

Re: 87 Johnson 50 (3 cylinder) bucking and kicking

I had that problem at the first of this year. The problem was debris in the bottom carburetor float bowl. It must have been getting against the main jet at times and starving that cylinder of fuel. Other times it would run correctly. Clean the carburetors and be sure to change the fuel lines. The fuel line was deteriorating inside and that was where the debris was coming from. Some say ethanol is causing that problem. I'm not sure if it was the age of the fuel line or ethanol in my case.

Good luck!