Crank it up, let it die as you say, and then pull the spark plug. If it is wet with gas then its probably the carb float sticking and flooding..... very common with the junk gas we now have to use. In this case pull the carb and do a good cleaning.
If the plug is whitish and dry, then suspect the fuel supply. Start by checking the fuel filter. If it has a good flow out of the filter, check the fuel pump to see if it is squirting gas to the carb.
If all is good there, then pull the carb off and do a good cleaning and use some carb/choke cleaner to help get any build-up out of the jets.
