Fuel Tanks - Steel Or Polyethylene?

I didn't have my '67's original steel underseat gas tank relined, but on the recommendation of a friend, I bought Bill Hirsch's Auto Gas Tank Sealer Repair Kit ARK-01, which seemed to substitute nicely: https://www.hirschauto.com/AUTOMOTIVE-FUEL-TANK-REPAIR-KIT/productinfo/ARK-01/

Prior to using the cleaner / degreaser, etch, and sealer in the kit, I had my tank media blasted externally, and internally as well to the extent possible. The blasting opened up a couple of very small, previously rust-filled holes in the bottom. After repeatedly rinsing the tank out with water to remove the remaining blast and rust particles inside, I used a heat gun to thoroughly dry it out. I filled the holes using the fuel tank repair putty that came with the kit, then used the remainder of the products as recommended.

That was 4 years ago, and I haven't had any fuel tank problems since.

 

Mine had about 100 pinholes. Sandblast and solder. Some holes I used a (copper) penny as a patch. It worked.

On other vehicles I have used fiberglas cloth and resin. Not sure about the legality of that, although some vintage Brit bikes had fiberglas racing tanks.