Barry tip is right on,,, mind want start either unless tank is over 1/2 to full,,,,, not sure ONLY A SUGGESTION,, can you take the air cleaner off and start it,, have done this with this car before,,, I normally was once a month on exercising the genie,,, now I go over and try to do it every two weeks three at the most,,,,, a lot of the cheaper brands of gas ( grocery store, Loves, etc) Most of use do not have the detergents in them that keep everything clean and lessens varnishing, that's why they are 20 to 25 cents cheaper a gallon,,, not that it means much, but I also noticed that when it is cooler weather seems to make small engines a little harder to start,,
good luck
sparky