I didn't expose the core. It was like that when I went to check it. Apparently at some point in the past someone felt the need to check it. I don't know which is heavier, water or gasoline. Water weighs 8.6 pounds per gallon.I'm assuming that the bared insulation was so that you could test at the switch.
Don't you just love it when the diagram shows two wires, and you see four!?
If you do end up dropping the tank, remember that gas will weigh about 10 lbs per gallon.