I had a 57 fastwin fixed up at a reputible marina but didnt have the rite tank, could have bought one from him for $150. My buddy had one i used it but had to keep pressing the primer to keep running. Another guy said the tank wasnt holding pressure and replaced the top seal, however it still does the same thing. Any suggestions. Thanks. Trapper
Nevertheless, the pressure tanks work like this: The motor pumps air into the tank while running. That air pressurizes the tank, and the pressure forces the fuel up through the hose to the carburetor.
So...You have two possible problems.
1. The motor may not be pumping air. Unusual, but it happens.
2. The tank may not be holding the air pressure, due to an air leak. The leak can be one of many places, from the seals in the hose connector, to the assembley on top of the tank, to a loose gas cap. You DO have the gas cap on tight...don't you?