I'm sitt-en here thinking..and ..The I-5 is a Fuel Injeted motor with a high pressure feed line from the tank to the fuel rail at the motor. I would assume that there is a bypass return line back to the tank for unused fuel at the fuel rail.
Wouldn't there be some kind of a pressure relief on the retun side ..in other words ..why would they vent the tank.? It's supposed to be sealed when you replace the gas cap ..other wise you get a Check engine light if there is no pressure in the system.
BWTFDIK.....
..............Take it
F5..