Various vehicles, particularly boats, use plastic fuel tanks because they are lightweight and durable. They are considered better than using metal tanks because the metal can leak, fracture and corrode. The plastic fuel tank is considered less costly and convenient because it is easy to put in. When the tank needs repairing, many choose to have it repaired rather than buy a new one.
Empty out the tank. There cannot be any fluid in the plastic fuel tank while trying to repair it.
Cut a few pieces of plastic for the fuel tank using wire cutters. How big the damaged area is will determine on how many pieces of plastic you will need. For a small hole, cut out about two pieces about 1-inch long and wide. Lay the pieces of plastic on a metal surface. Use a heat gun to heat the plastics until they are transparent and tacky.
Use the heat gun to heat up the edges where the fuel tank needs repair. Begin with one piece at a time. Only heat up a part of the area that you will begin with. Once the edge is softened then stick the loose transparent plastic on. Use tweezers to hold the loose plastics and to stick them onto the tank.
Get the hot knife and smooth out the softened plastic. Run the knife from the top of the area that you stuck the piece of softened plastic on and take it to the bottom of the fuel tank.
Repeat Steps 2 and 3 for the remaining pieces of plastic until the area that needs repair is covered. You can also use a spoon to smooth and spread out the molten plastic if the damaged area is bigger than a puncture.
If the plastic pieces turn brown then they are no longer any good.