First thing I'd do Dreno is pull the plug and stick your finger over the hole and hit the starter or pull the rope. The compression should try to blow your finger off the hole. Another thing, is your spark should be a good blue color, if not pull the engine end cover (where the rope starter is) and there will be an ignition coil with .010" clearance to a magnetized portion of the flywheel. Also remove the 2 bolts that hold the coil to the engine block and make sure the ends of the bolt/spacer and side of the coil are clean and not rusted. A lousy ground will give a weak spark. I had this problem last week, lousy spark but I had gas and air wouldn't start. Now I got a blue spark and starts on the first pull. (Fried the starter last week, $225 for a new one, not a chance).