Also check the pickup tube and screen. You'll have to separate the gas tank from the carb to do this but I've found many that were clogged or plugged...particularly if they've been sitting for a while and especially if they were the 5hp model. If you put a bit of gas in the spark plug hole, replace the plug and it starts when you crank (or tries to start), it is a good indication you're not getting gas through the carburetor.
