Gas + air + spark = oughtta run. Badly, perhaps, but it should fire.
My guess is water in the tank. You've got the classic symptoms. Reminds me of this one time my sister left her gas cap at the pump, so "borrowed" the one off my 2nd car. "Oh yeah, I forgot to mention that..." Worse, by the time I got around to figuring out why it wouldn't start, it was winter and the freezing "gas" wiped out my fuel pump. By the time I got around to fixing that, the motor had rusted seized. Perfectly running --- and totally rare --- X-11.....history....eventually..
I've yet to let her live that down. It'll probably be a death bed thing for me.