"JohnR66" wrote in message
...
I have a 3.5 hp B&S "classic" engine. While mowing, it started sputtering
and surging like it was about to run out of gas but it has plenty. It does
this in any throttle position. I took off the carb and cleaned the
strainer.
It had some junk, but wasn't very dirty. After I put the carb back on, it
ran fine for 3 minutes then started surging again. One thing I noticed is
that it will run smooth seconds before it runs out of gas. Sounds like a
carb problem, but I'm not sure.

Thanks for any help.
John


Thanks for the replies so far. I failed to mention that I ran it with the
air cleaner off and had the same result. After reading the posts about the
gas cap, I checked and can see that the holes are not plugged. I should
mention that the carburator is the type with the priming bulb. The
carburator appears to be molded out of nylon plastic and bolts to the gas
tank with 5 screws.
John