[Blacky]

"One other thing: there have been a couple times when the vacuum inside the fuel tank was large enough that when I opened the gas cap I got sprayed with fuel from inside the tank as the fuel vapor in the tank vented to atmospheric pressure and dragged some liquid fuel with it as it rushed out of the filler pipe".

My '97 does this all the time. I think it's positive pressure though. I haven't investigated the cause. I open the tank very slowly and let the pressure release. No emission tests here thankfully.