'92 Johnson 120 Possible Carb issue?

[Doug Market]

I have a '92 Johnson 120 which has run very poor since last season. It seemed as though I was losing cylinders and running in the driveway with ears on was producing big blobs of oil. Eventually the boat wouldn't start and a spark test showed no spark from any coil so I replaced the power pack and now have solid spark. I also changed plugs and tried the boat out again but still runs horribly. It smokes heavily (blue and white), dies at idle, and will not show any power unless my wife sits on the front deck where it will slowly gather speed until it fouls out. It sounds very rich but new gas is mixed 50:1 and I mix directly. It seems like my dead power pack wasn't my only issue.

Compression checks 120, 120, 125, 128

What should my next step be?

 

[noelm]

Re: '92 Johnson 120 Possible Carb issue?

you have a reasonably simple and very powerfull motor, how about some very easy things first off, like a complete remote tank, hose and fresh fuel with the correct mixture (if you premix) and a set of new plugs, check to make sure the throttle is actually working the carby butterflies and opening fully, and make sure the choke is fully off, from there it can be determined if a carby rebuild is in order, also a fairly simple job if you take your time and are mechanicaly minded (and have a genuine manual)

 

[noelm]

Re: '92 Johnson 120 Possible Carb issue?

OOOPS I just read you have replaced the plugs, so make sure trhey are the correct ones and gapped right.

 

[Doug Market]

Re: '92 Johnson 120 Possible Carb issue?

Thanks for the reply.

Two weeks ago I did use new fuel mixed 50:1 and had the same issues. My hose looks in perfect shape but I will replace just in case. Carb butterflies are functioning fine but I will check the choke to see if it's sticking.

Thanks again and I'll get back to you with the results although I may not be able to do anything until tomorrow night.

Any further guidance would be appreciated!

Doug

 

[tashasdaddy]

Re: '92 Johnson 120 Possible Carb issue?

is your Vro oil tank still connected? if not

Ethanol and fuel lines
replace all fuel line with Alcohol resistant lines. Ethanol deteriorates, the rubber lines, then they start to sluff off on the inside, going directly to the carbs. Settling to the bottom of the bowl. Contaminating the carbs high speed jets. clean a rebuild carbs, flushing fuel line before connecting to carbs.

 

[Doug Market]

Re: '92 Johnson 120 Possible Carb issue?

Ok that does make sense, thanks again guys.

Is there a good place to get info on rebuilding these carbs?

Doug