Skipping/dead cylinder...why the fouled plugs?

Joined
Jul 15, 2008
Messages
24
I have an 81 Mariner 2 cylinder 15hp 2 stroke outboard. I recently rebuilt the carb and replaced the spark plugs. It has run fine for about 2 weeks and suddenly it runs really sluggish...so of course, I docked it and pulled one wire at a time...the top cylinder wire when pulled still runs, but when the bottom only is pulled, she wont start. (Both cylinders have spark for sure - bzz bzz bzzz :D) I also noticed very small whitish chunks that spewed out of the exhaust that dissolved in the water. (ash?)
When I take it out and run it, at wide open throttle it runs at 1/2 power and 'pops' a little surge of power from time to time. Am I running the carb too lean? Anyone else hear of this?

(If this helps with the carb issue, I rarely need to pull the choke to start it)
 

JB

Honorary Moderator Emeritus
Joined
Mar 25, 2001
Messages
45,907
Re: Skipping/dead cylinder spits white chunkies...what cause?

Re: Skipping/dead cylinder spits white chunkies...what cause?

Not likely a carb problem, WSG. Both cylinders use the same carb.

What the two cylinders don't share is ignition, reeds, bypass covers, head gasket surfaces and the mechanical parts.

Spitting out chunks could mean that it swallowed a reed or part of a gasket. I would start with a compression test and go from there.

Let us know what you find.
 
Joined
Jul 15, 2008
Messages
24
Re: Skipping/dead cylinder spits white chunkies...what cause?

Re: Skipping/dead cylinder spits white chunkies...what cause?

To clarify, the chunkies arent solid material, but looks like ash...going to go clean and gap the plug today..
 
Joined
Jul 15, 2008
Messages
24
Re: Skipping/dead cylinder spits white chunkies...what cause?

Re: Skipping/dead cylinder spits white chunkies...what cause?

Ok...I have good compression..110 on each cylinder...I think it's just a fouled plug...I found one spark plug would run whichever cylinder it was on, while the other would not (did this by disabling the other cylinder, so I could test one plug at a time.) So, I know the plug will have oil on it, cuz its a 2 stroke, but im guessing its either fouled or just a bad plug. ....update....so I replaced the plugs and it runs fine...now...back to the cause of the plugs...could it be a bad carb adjust?
 
Top