Also check for air leaks. These engines are very sensitive to any air leak at all in the fuel system. If your tubing connections aren't completely airtight, it won't pump fuel. I've had problems with fuel tubing being tight at first, and then loosening up and leaking air after being exposed to gasoline for a while. (Especially if the gas has ANY alcohol in it.) I usually use some sort of tie wrap to secure my fuel line fittings. A "wire tie" off a loaf of bread will work in a pinch.

Hope this helps,
AV8TOR