Fuel tank repair

What is your question?

The exhaust pipe got pushed up against the gas tank burning a hole in it because it's plastic. Cut out a piece from another gas tank and melted it into place over the spot that got burned (after cleaning and sanding it and made it so the plastic would fit nicely) then used a JB Weld to seal it. But there is still a spot that leaks a little bit. What would be the best way to stop it?