Checked the venting and realized it wasn't venting at all.
The filler neck was originally installed to use the standard LeMans cap with no other cap underneath. When I took it to the track, I had to put a cap on the tank under the LeMans cap, so bought one of those locking caps at the local store. However, the vent line underneath that hadn't been connected.
I thought it was, but then found it was a drain line from the indendented area around the fuel cap to allow overflow to drain off. So, have installed a 3/8" fuel line from the vent outlet on the filler neck to underneath the car. Also tightened up the connections and such as well. Hopefully that will do it.
Track day tomorrow at Road Atlanta - yee haw!
Thanks!