I have a 97 Challenger, and I was wondering what the 3 "valves" are that are located under the back deck adjacent to the fuel filler, 2 of them have 2 sets of "gas pump" icons beside each, and the other valve has a cap with a chain connected to it, I have ordered a cd manual for the boat so I could learn what some of these items are, but have not received it yet, I would appreciate any information on the purpose and use of these 3 valves.