There's no liner to worry about, but sand the tank in the area first to remove the shiny surface so the patch material will stick.
My mother hit a huge piece of metal on the highway with her Grand Caravan. It tore off the rear heater hoses and punched a hole in the tank making a 3" x 1" cut two sides of a rectangle. It was up high enough that she only lost 3/4 tank of fuel. By leep-frogging it with my car, I nursed it home 7 miles with no coolant. Half way home, I crawled underneath, sanded the tank in the area, (metal tank), and built up a temporary patch with Mopar RTV gasket sealer, (the harder, better-sealing gray stuff). Never smelled any fumes from that point on.
While repairing the heater hoses at home, I decided the "temporary" patch was vulnerable to rocks, so I added a thin piece of tin over it. Decided the tin was vulnerable to corrosion so I added another layer of gasket sealer. That was 20 years ago! It's still my dailer driver and has never had a sign of leaking. I always overfill the tank. I've even given up watching for a good used tank. The hole is WAY bigger than 1/8".
You might consider using RTV, (room temperature vulcanizing) gasket sealer, and for good measure, run a self-tapping bolt with a washer into the hole with it.
Not sure what rare elements your tank is made of, but for $700.00, you can get a half dozen good tanks from the salvage yards.
Monday, March 15th, 2010 AT 2:48 PM