I'm buying a 16 wahoo 1987 , the boat hasn't been used in a few years and needs some TLC. The big issue is the internal gastank which is mounted under the center bench seat has problems. I'm told that there is a anti siphon or one way valve that is stuck and not letting proper gas flow to the engine. The engine runs fine with an external 6 gallon tank. Anyone know what I'm talking about one marina guy siad I may have to cut part of the fiberglass off to get access to the tank any info would really help.Thanks in advance