Just got back from my trip to the Alps and got to a little smelly problem. I drive a 1999 1.6 impreza which has a bi-fuel system with direct injected propane (or LPG). For starting I use gasoline till the cooling water reached a certain temperature and then the computer switches off the fuel system and continues with propane. However in Italy there is a village named Livigno and they sell normal gasoline almost half the price of where I live (tax free). So I filled it up completely at 3280 feet altitude. I continue my trip into Swiss over a mountain pass at 7200 feet and the car starts to smell of gasoline at the rear. I switched to run on gasoline to what I think to release the pressure in the system.

 

Does gasoline expands at higher altitudes, enough to overflow or at least smell a lot?

I have seen gasoline expand with higher temperature, if it was cool when filling, then warmed up later, as the day's temperature rose. I don't think altitude would make any difference.

it was cold in the morning I filled, about 18 deg C, later on the day about 29. Plus the heat from the diff and exhaust

 

(i lost a piece of heat shield of about 3 by 8 inches have to figure out from where)