Carb issue??? 1990 20hp Evinrude

My dad bought a boat from a friend. The motor sat up for several years. He soaked the carb in carb cleaner and even boiled it for a couple of hours. He used a new fuel tank with fresh gas.

It will crank for just a second if he sprays starter fluid into it but it stops as soon as it burns it up. There is fuel in the bowl of the carburetor.

Any idea what is wrong or what he can do to test or fix it?