Which model Enya is it? If it's the early cast iron piston with the removeable front end then check to see if the top right hand screw is tight. This leads directly into the crankcase and will stop you from priming if it's leaking. From memory these carbs are held in by short screws either side of the carb so check them for leaks too. I think there's also a gasket where the carb seats.

If it's the cast iron piston then I hope you're using lots of castor in the fuel