Merc 2 Stroke Won't Stay on Plane

[CTsalt12]

Hi All,

My '97 Merc 115 doesn't seem to want to stay on plane.  I take off and it gets up fine, plenty of power.  Run for a few minutes and then it bogs down.  I can hear it hesitating like it is getting power then losing it, fluctuates.  I replaced all fuel lines which I definitely had issues with before.  Clogged vent line etc.  The gas is good.  I did have issues with water in gas end of last season.  I drained it and it rain fine with new gas at the end of last year. 

So it won't stay fully powered.  The fuel bulb is NOT being sucked flat flat.  When I use the choke it can help me stay powered. 

Based on some research it seems this can be a carb issue, the carbs may need to be drained or cleaned.  Or it can be a stator issue.  Or my engine is ready to be trashed?  But I used it reliably all last season with the exception of my fuel issue at the end.  Like I put a lot of hours on it.  I fish 2-3 days a week May-October running all over the  place.  So I don't think it's ready to be trashed just yet...Carbs haven't been cleaned in three years.

What do you all think?

[Woodeneye]

Strip down the carbs and clean them. Sounds exactly like my problem at the end of last season. Cleaning sorted it. BTW if you aren't proficient at it or lack the patience, like me, get them professionally done.

[wingtime]

Do a compression test.

Then clean the carbs. Do you use ethanol fuel?

[CTsalt12]

Do a compression test.

Then clean the carbs. Do you use ethanol fuel?

Yes, unfortunately.  My ignition key is ancient and doesn't seem to have a killswitch which makes the comp test a lot harder as I have to involve someone else's boat and 3 jumper cables..  Unless there is a better way to do this.  It seems this is the recommended method in Seloc books.

[Xjbob99]

sounds like a fuel delivery issue. Im not familiar with the mercs but my evinrude was having issues similar to yours. mine ended up being the fuel pump.

[love2fish]

if your fuel hoses were bad enough that they needed to be replaced- your carbs will most certainly need attention. get those cleaned and then do a comp test. easy/obvious stuff first before you start replacing stators and trashing motors

[CTsalt12]

This is ancient but figured I'd let you know the result.  Carbs did need to be cleaned.  Mechanic mentioned that as a result of fuel vent issues I mentioned, top cylinder/carb wasn't getting fuel through it and got gunked up.  It's been running great since then.  I also don't need to choke it when I start it anymore, which is nice.   

[wingtime]

Good news.  That clogged up carb could have wasted the cylinder in no time due to lack of lubrication.

[RickK]

Good news.  That clogged up carb could have wasted the cylinder in no time due to lack of lubrication.

That's good to know!