"Ashton Crusher" wrote in message
...
On Sun, 3 May 2009 11:21:26 -0500, "Nelly Wensdow"
wrote:

I have a 15-year-old Sears 4hp mower that I change the air filter, plug &
oil each spring. It started & ran fine last week for the first mowing,
but
now it acts like it's running out of gas. Runs full fast then slows way
down, back up again, etc. What could be causing this? TIA


Does it have the carb with the round fuel bowl that is held on with a
single bolt at the bottom? I had a sears with that carb that did
exactly what you described and it turned out to be a bunch of water in
the fuel bowl. Took the bowl off, emptied it and let some gas run out
and put it back together. It ran fine and then started doing it again
and I repeated the draining and it's been fine ever since. The first
time I drained it you could see the water 'bubbles' in the gas in the
fuel bowl.

And if the float is OK a couple other things to check--is the choke staying
on? Sometimes the cable will become loose and slip a little, the choke will
stay on, and it will run until it warms up. Also check the tension on the
governer spring. They can also become loose (stretched) over the years.
There should be just the slightest tension on the spring with the engine off
(assuming it's the type that I'm guessing OP has).