ORIGINAL: JoeAirPort
Dirtybird is correct. You need a switch and pump combo that doesn't generate an exposed spark or you have designed a spark plug and an engine that fires once. You might get away with it...forever. But it's not good practice....and it happened to his friend. He's on topic and so am I.
Okay, Joe and db - assume for a moment that we agree that you are correct. Please explain how the vapor density gets to a combustible level in open atmosphere, with ambient normal flying field conditions, wind, etc.....and explain how this explosive vapor forms and REMAINS around the switch location, or the stator of the pump motor, without dissipating??? If you can explain the atmospheric physics that contains the vapor alongside my airplane from a "vent line", and I will become a champion of your science.
Really.