Originally Posted by Rax

Is it a metal or plastic tank ? From my own experience for a metal tank that petrol patch stuff will work but you need the tank empty otherwise the stuff will not go off and harden.As said you need to key the surface so it sticks.
If plastic as a temporary measure I once cut a fuel can up and melted the pieces in place with a soldering iron.This was on a motocross tank after trying allsorts,tigerseal,fiberglass and anything else I could get my hands on.
Put a screw in it