running on one cylinder

[churchboat]

I have a Johnson 48 SPL and unless I am at full throttle it is running only
on the bottom cylinder. It is blowing gas from the top cylinder back into
the cowling. Any ideas what I need to do? Thank you

 

[Benny1963]

Re: running on one cylinder

check spark on top cyl ,check top plug for fuel fouling you may have a carb dumping fuel into top carb killing the plug bad needle and seat impropoer
.float adjustment or bad float ,but spark check that cyl first
may want to comp check both cyls

 

[tashasdaddy]

Re: running on one cylinder

agree check spark and compression. but 99% clogged top carb. also could be a bad reed valve, but that is rare. i would clean and rebuild both carbs.
http://forums.iboats.com/showthread.php?t=299680