I was changing a fuel pump in a Buick century for my neighbors sister and it was about 3/4 full and she wanted to see what the inside of the tank looked like after I pulled the pump out. When she leaned over she dropped her cigarette right inside the tank and nothing happened.
It did freak me out and I took a big jump back but all it did was put the cigarette out. But my friend Alex, like a idiot when we were out riding our quads he used his lighter to see how much fuel he had left in the tank and the thing lite up. He had flames shooting out of the tank and we smothered it to put it out.
