If a small engine has sat for over a month, even before trying to start it, drain the old gasoline from its tank.
Gasoline that has sat for over a month has started to turn into varnish; it has a bad-varnish smell unlike fresh gas.
Varnish-gas will not work well in any engine and may make starting impossible.
Add fresh gas; if it's a 2 cycle engine, follow the directions in the owner's manual to add the appropriate quantity of oil to the gas ~before~ putting it in the engine's gas tank.
