yamaha outboard dogging at full throttle.

[robert_leisure]

I have a 85 115 yamaha which has been a awesome motor till this spring. Starts fine, idles fine, and runs good to half throttle. Now when i punch it, it doggs down to a crawl. Fuel bulb stays hard all the time. Recently changed plugs. I cleaned fuel lines out, fuel filter, and replaced the fuel pump today. Diaphram on old pump looked fine. Recently in the shop before this problem and mechanic said everything a ok, including compression. My next guess would be clogged jets. Can i access the jets without tearing the carbuerators apart? Or any other suggestions out there? Thanks.
1985 16 1/2 skeeter with 115 yami, jackplate, stainless steel prop. top speed 65mph. Now thats mowing in a 16ft'er.

[1st grady]

A simple solution may be to spray some power tune or whatever 2 cycle carb cleaner is available to you and let them sit for about 1/2 hour or so then run the crap out of it. You may need to do this several times, this worked on my snowblower, neighbors lawnmower (saturday) and my dad's snowblower. I am no mechanic but when I detect a fuel delivery problem this is my first step before tearing anything apart. (after trying fresh fuel of course)

[Ken]

robert,
Go back thru the previous posts and find where "Hamfisted" talks about cleaning the jets.
I believe you can remove the low and high speed jets and clean them without overhauling the carbs.
Good luck,
Ken K

[robert_leisure]

Thanks for ur replys. much appreciated.

[robert_leisure]

what about float bowl levels. If their off the engine could be starving for fuel wide open. Correct?

[Ken]

robert,
I would not suspect float bowl levels since your motor is running fine up to half throttle - if they were stuck in the up (cutoff) position, then I think you would be having problems before half throttle.
Clean the jets - and if that doesn't fix it, maybe do a carb tear-down and cleaning (new gaskets, etc.). If that doesn't fix it, I would suspect ignition timing problem. In any case, get yourself a Yamaha shop manual. Go to yamahapubs.com or boats.net(sponser of this message board).
Good luck,
Ken K

[Hamfisted]

Robert pull the main jets out of the carb bowls and inspect them for any debri clogging the orifices. Get some Berryman's Chemtool spray (Walmart) and spray everything out. Spray up into the carb bowls to flush everything out too. Also inspect the orange O-ring seals on each main jet for any distortion, tears or cracks. Replace any that don't look good. They're about $5 apiece at the dealer (only). Use Sea Foam in you fuel tank to condition the fuel and fight carbon buildup. Good luck.


Mike ....... Miami, FL