This is a little off the subject as it concerns a stainless steel
potable water tank. Mine started leaking almost as fast as I filled it. I got it out and the welded seams were rusting and leaking. After many conversations and replacement prices with folks here in the NW I finally got the idea for Rino Hide. The same stuff they put in the back of pickups. I took it to a local installer and he fixed me up Rino Hide all over the tank for about $125. It was only a 30 gal tank but a lot of slants and seams. Now they also told me their product works on fuel tanks. It seals
everything. Just be sure you have the intake and air escape elbows in the correct direction I did not and that stuff is unforgiving. Meaning it will not bend or break. I had to add a couple elbows to get the correct directions again. I don't drink water out of the tank anyway so not worried about any contamination. I only use it for washing
up as I don't like the taste of the tank water even before the Hide treatment. I just drink bottled water. You won't have that problem with a fuel tank. The folks said they repair fuel tanks on the fishing
boats here so it may be a less expensive solution. Just a thought.