Re: 1989 Hunter 40 - A million questions.
Had a boat with 2 fuel tanks...I think yours might have this. It also had 2 fuel selectors, one for the supply line, one for the return line. The "classic" mistake would be to supply from one, and return to the other. If you accidentally did this, you would over time move your fuel from tank A to tank B, and eventually overflow tank B.