Reginald P Smithers III, Esq. wrote:
Mike Slater wrote:

"Eisboch" wrote in message
...

"Mike Slater" wrote in message
news:knfZl.742458$yE1.158636@attbi_s21...
I was cruising along in my 24ft pontoon boat when I got a real
surprise. Somebody please tell me how and why I could be running
wide open throttle at my normal 5500 rpm and then suddenly the boat
took off like a bat out of hell running at 8000 rpms and 25mph??? I
never touched the throttle. It has never run that fast ever. After
about 2 minutes it went back down to 5500 and never did 8000 again.
Its a 60hp mercury Bigfoot outboard. It has never done this before
and I don't even know how it could rev that high and go 25mph.
Normal is 5500 and 17mph. What happened??

Mike


Is it a two stroke? I've often noticed on 2 stroke weed wackers or
chain saws that just as you are about to run out of fuel they speed
up. I think they start running lean due to air in the fuel line.
Is it possible you had a temporary air leak in a line and a similar
thing is happening?

Eisboch


Yep. Its a two-stroke. It really caught me by surprise. Next time I
will look at the clear inline gas filter down near the primer bulb to
see if its empty if and when it happens. It was only my second outing
this year so who knows what going on and was too shocked to think
about looking at the fuel situation. You know, it sounded great at
8000 revs.

Mike,
You may want to consider dropping back to a "cruising" rpm, instead of
running it WOT. Running the boat at WOT will shorten the life of the
engine considerably and use about 3 times the gas. For most boats, the
best gph or mpg is about 3400-3600 rpm. You shouldn't pick up much
incremental speed at WOT.

Excellent advice especially if it is an older motor drawing it's last
breaths.