Fuel pushing out filler tube

So you dont think fuel moving out of the tank and returning would create pressure from the fumes alone?? Do you think its just the temps that allow for expansion. One problem that relates to this would be the fuel fills right up to the filler area before it kicks off as full.
Saturday (or anytime I put fuel in it) when I filled it up the nozzle wont shut off before it's right to the top of neck. I even turn the nozzle upside down and very slowly fill. This way is does not splash out while filling. But once its full it always spits gas back at you.
As for put a vent in it I can do that but wouldnt or shouldnt it vent thru the vent already in the filler neck? Where do you suggest a 2nd vent in the tank should go?
The filler tube is the stock filler and no locating has changed with the tank or neck.
I remember as a kid these were always hard to get gas into without them kicking back at you. Believe me I've had plenty of gas baths from the older cars as my dad had a gas station and I was fortunate to have to pump gas everyday for over 10 yrs of my early life!
Thanks for everyone's help and ideas
Rod