I can see your picture that you posted. Each tank can usually only leak from a few places. The filler tube, the overfill tube, the fuel line going in, the fuel line going out, or a seam in a metal tank. Also, seeing as how A lot of pumps are made of plastic, it could be leaking from there also. As I stated before there is also a rubber O-ring between the pump and the tank which could also leak. Other than that, that is it, unless there is a hole in the tank. Please be cautious