I know that the proper thing to do is replace a rusted out metal hose or tank but I have had good luck once with a cheap fix that a mechanic friend told me about when I was very hard up for money. I was driving a Chevy truck and it developed a gas leak in the very bottom of the tank. His advice , and it worked for years afterwards, was to drain all the gas, use a screwdriver CAREFULLY to make sure the metal around the hole is solid clean up the area with some coarse sandpaper and mix up a palmfull of coarse body fill. Take the body fill and scrunch it into the hole. Don't play with it, smooth it or anything else. 24 hrs later I put gas in and drove the truck for years without a problem. Used to occasionally look at the patch but finally stopped because it always looked the same, ugly and dry. Just a thought depending on how tight money is.