Blue Man did you happen to notice the fuel primer bulb when this was happening, some of what you are saying are problems I had with diffrent motors over the years and they traced back to one, fuel bulb, even a new one cause they are all crap now, two, fuel pump on the side of the engine.
If not those and the plug pull does not reveal any issues in one or more cylinders time to run an auxilliary tank.
Also a good run like you had last week in some rough water can combine with the ethanol crap in your gas to dislodge a lot of sheeeet in your tank and lines, check your in line filter and the fuel/water seperator, you are likely to find unidentifiable sheeet in one or both of them.

Oh yea one more thing, when was the last time you gave that puppy a decarbing of the cylinders?
Carbed up cylinders cause all kinds of sheeet, over heating, timing issues believe it or not, due to uneven compression and detonation along with reduced flow of the exhaust and intake, the cylinders never carb up evenly.
Thats all I got for now Dawg

Changed plugs, check. Cleaned all filters, check. Ran on auxillary tank, check...none of which fixed the problem. Time to :head::head::head:

This is a bunch of :bsflag:I am supposed to be fishing for the next 2 weekends!!

When I get home I'm going to pull the new plugs and check it out good to see if I can tell if there is a cylinder not firing. If I can't tell I'm going to put the old-new plugs back in and do a decarb session, then put the new-new plugs back in. If that does not fix it I'm going to use my 9.9hp the rest of the year!! Not really, but that is what I feel like doing.

Will update when I know more. Thanks to everyone!

Next step for me would be a carb rebuild. Its not that difficult as long as you have the FACTORY repair manual. I'm betting you have some debris floating around in your carb bowls. I'm not sure about Yamaha but you may have a screw at the bottom of each bowl that you can loosen and let them drain and shoot some carb cleaner through. Its not the right way to do it but it may work.

Thanks Mulv for the advice...but there are 2 things that I don't know jack doo doo about....they are carbs and fiberglass.

Not a good father's day for Blue. Does anybody want to fly in to NC to help me fix this?
:cry:

Blue, the carbs arent like what your thinking. There are no adjustments for air or idle screws or any of that good stuff. If they are like my 2000 Johnson 150 all the jets are fixed no adjustment required. You take each carb off, unscrew the bowl, shoot some carb cleaner through the jets, blow some compressed air through them, replace the gaskets, new needle, seat, and float, re-install. Sounds complicated, but its not.

The only thing that can be tricky is the Lync and Sync but alot of motors you don't have to disturb the linkages to remove the carbs. Trust me I have rebuilt carbs on 4 different motors and I'm no master mechanic, its that easy.

Hmmm....wonder how much round trip air fare from Philly to NC would be? :sun:

Probably cheaper than hiring a mechanic!

Ok, I might just have to dig in to this beast. I don't want to though.

Well BLUE, your YAMAHA uses the old style OMC carbs(the ones they copied off of OMC back when they first started building them). They do have adjustable idle circuits in them, but the mid and high's are fixed. There are 6 bowl drains you can pull out, and I would reccomend you do this before you take it to somebody. You can look up diagrams and parts here.

http://www.yamaha-motor.com/outboard/parts/home.aspx

Ferm, thanks bro!

Here is a little more info. The boat idles and runs great. No funny noises, stalling sputtering or anything like that. The ONLY thing that is wrong is it won't reach full RPM's (off by 500) and you can tell it is sluggish. It will consistently will make 4500 RPMS and 34 mph trimmed up sucking ducks as Reel would say. No variation whatsoever.

I just talked to a local shop and of course he's 2 weeks behind and he says my symptoms do not sound like carbs....said it sounds more ignition based and that I might be dropping a cylinder. If that is the case then what am I looking at here? Stator? Do these mamajamas have powerpacks? What else? When I check the plugs it should be obvious if one is not firing as the plugs I just installed are brand spanking new.

P.S. The shop said a ballpark figure on a carb rebuild is $150 per carb - OUCH!

Thanks!
Blue