Six months ago a friend of mine asked me to fix his VN1600 which hadn't been run for 2 years and wouldn't start. It was parked in a shed with a tank full of fuel. Alarmingly, the inside of the tank was quite rusty, I saw, after draining the foul smelling and discoloured fuel. I filled the tank with white vinegar and left it for a few day to eat the rust away. After flushing the tank and replacing the fuel pump, which was seized, I filled it with fresh fuel to find it leaking from the overflow tube under the bike. At the bottom of the tank it's connected to a steel tube that runs inside the tank to the filler cap. OK, I thought, I'll just plug the drain tube. WRONG! After riding it for about 5 minutes fuel began to flow from the filler cap as the fuel expanded, soaking my jeans in a very sensitive area of my anatomy and down my legs. I was tempted to park the bike and call for help - not wanting to go up in flames, but I decided to ride back home and take a chance. I'm here now to say that I didn't go up in flames but it was very scary as the exhaust had been chopped slightly back from the seat at 'peg' height.
Apart from getting another tank, the only way to fix it was to feed a wire down the tube and pull a length of 1/8" heat shrink tubing through, seal it at the top of the tank/tube where it entered the steel tube/tank and under the tank where it exited the tube/tank and then carefully reattach the rubber o/flow tube so as not to damage the silicone sealant I'd used there. Heat shrink tubing is unaffected by fuel. I left about a half inch protruding from the underside so that it went inside the original rubber o/flow tube. This solved the problem and it's been that way since.