[bigeasy1]

I've had a couple fuel problems over the last couple of years.Once being when I was filling up at a gas station.I started pumping in gas and after a couple of seconds,fuel started backing up,and came shooting out of the deck fill,covering me in gasoline.It was a scary experience.
In my case,it turned out to be a spider that made his nest in the fuel vent.The vent did have a screen on it,but that 8 legged critter had his silk embedded into the screen.We cleaned the vent and it was good from then on.

The second was a bad sending unit gasket as mentioned by Denny.I was getting this strong odor of gasoline below the decks every time I filled the tank at the marina.I couldn't figure out where it was coming from,checked all hoses,clamps etc.It wasn't until i looked at the fuel gauge sending unit from a slight angle. I could see a dried up halo like stain around the sending unit.
I ended up replacing the whole unit with a new gasket,and it solved the problem.Looking straight down on the unit didn't show any stain or leak,but it showed up when looked at from an angle.
I only had the issue when I filled the tank,so like you it had to be something like Denny mentioned, either the angle of the boat when filling it or a bad gasket.Denny also recommended the #2 permatex to me,so I did use it,but very sparingly and so far it's good,no more fuel odor.