Possibly it has water in the tank (from dew/condensation). Perhaps
empty the tank and put in fresh gas.

Richard wrote:
Folks, I have an older Craftsman lawn mower that I can't get to start.
I do get a good spark, so I'm assuming that it means a clogged
carburetor. Is there anything that I can pour into the tank and allow
to sit there that might help dissolve any old varnish? Thanks in
advance for your suggestions!