Mighty Favog Posted August 23, 2007 Share Posted August 23, 2007 Well, as we're into what feels like our 9th year solid of triple digit weather this thought came to mind as I was thinking about summers gone by. About 30 years ago I was helping out at a newspaper drive at my elementary school loading grocery bags into a large semi-trailor. I looked out into the parking lot and the gas cap to my father's pick-up truck blew it's top and fuel was spraying for yards around. At least until the pressure dropped in the tank enough. So my ponder was with newer cars can the internal pressure get so great with the heat and the expanding fuel that it could flood the emission's evaporative canister. I mean, it seems to be encouraged to fuel up after 6pm and along with that the fuel is actually cooler at that time. hmmmmmm.............................. Quote Link to comment Share on other sites More sharing options...
pauln Posted August 23, 2007 Share Posted August 23, 2007 I think modern cars use a venting system. I think the reason we are advised not to "top off" the tank is that this interferes with the operation of the venting system... Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted August 23, 2007 Share Posted August 23, 2007 The new vehicles have an evaporative emmission system which is designed to be sealed. Monitors in the vehicle check the status of the system when you start and periodicly when you drive. If it senses a leak in the evaporative system (or loose gas cap!!) the "check engine" or "malfunction indicator lamp" (MIL) will illuminate. The government does not want gas fumes from your tank vented into the atmosphere. Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted August 23, 2007 Share Posted August 23, 2007 BTW, there is a vent, but it is used to let air in as the fuel level in the tank drops. There's also a charcoal cannister which can fill with fuel if you overfill your tank. Quote Link to comment Share on other sites More sharing options...
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