Michiel wrote:
Hello,

I have a 3hp Sears Gamefisher aircooled outboard. It's Tanaka 300 with
Sears brand.

It developed a problem:

After running at full throttle with no problems for 10 minutes os so,
it'll start to cut out. The engine speed will drop fast. At first,
it'll keep running and pick up speed again, but it will cut out again
and if I don't close the throttle, it'll get so bad that the engine
dies.

Running it at low rpm for a while eases the problem: I can then get
back to full throttle and it'll take a minute or so before it starts
to cut out again.

Because of the initial time without problem, I'm thinking that the
problem is heat related.

I cleaned out the carb and put in a new spark plug, but no relief. I
also verified that there is good flow through the fuel valve and hose.

Any idea what this could be? Is it more likely an ignition or a fuel
problem? How can I troubleshoot this?

I'd appreciate any advise or pointers.

Thank you,

Michiel

Too much oil in the fuel mix makes the engine run lean and hot. My
old Kawasaki 2 stroke used to get tight and run rough and slow when
it got hot. Not enough gas means some of the carbon monoxide
usually wasted in the exhaust burns, too, producing more carbon
dioxide in the exhaust. Did you ever notice how an engine runs very
strong for a moment as it runs out of gas? It's the reason a car's
catalytic converter gets hot, the monoxide is burned to make
dioxide, producing heat.

That's what I was told.

It destroyed my chain saw- got hot, loosened everything up, shook
every bolt loose and let the chain oil tank rub on the flywheel.

It's an old saw, can't get a tank to fit.

Live and learn. Don't "protect" your 2 stroke by putting in too much
oil.

How come cars don't run lean enough to burn all the monoxide? It
seems like it would improve mileage if it could be managed properly.

YMMV

Terry K