This suggestion was meant as a temperary solution until you can replace the tank. I've been a firefighter for 29 years and after responding to numberous MVA's with punctured or leaking fuel tanks, this method worked on even some large punctures. I learned this trick from a seasoned mechanic back in the '70's (By the way, I've yet to see a car blow-up as a result of fuel leaking. LOL... A few have burned to the ground though!)