long cranking times after sitting 2 weeks or more

Is this because of the gas evaporating out of the carburetor? OR do I have an issue with the carb float, or a check valve in the fuel pump that is allowing fuel to drain back to the tank?

Any suggestions and or remedies? One thing I enjoy most about non FI engines is that they start at the turn of the key... and I want that to be true even if the car sits a month or two...