The hoses from the expansion tanks should be clamped. Check the "Y"
fittings and all hoses to/from them.
I had a similar problem, I could see fuel leaking from one of the hoses
on the right side expansion tank.
Anyway, Tom Hanlon gave you some good advice.  My advice would be to not
cut corners.  Take the time to ensure that every connection is right or
you will do what I did which was to R&R the tank about a dozen times.
When in doubt, clamp!

Good Luck

Bill Kenneke kenneke@clis.com
"85 Wolfsburg GL, "The Cool Camper"