The wax on floss is there as a lubricant so the floss slides more easily on the tooth surface. It is likely a petroleum or synthetic wax (polymer), both of which will be soluble in gasoline. As the floss loses the wax, its dimensions may shrink, and allow the main jet to draw fuel around the edges rather than through the orifice, thus upsetting mixture. But I could be wrong, so good luck and let us know. Don