I finally figured out how to get my gas cap to stop leaking gas onto the outside of the top cap, but the cap does not vent fumes now. I unscrewed the the little surge valve on the center of the cap and filled it with RTV, so the cap now makes a tight seal and keeps gas in. But the tank does not vent as well now and I noticed that when I pop the gas cap, you can hear the pressure release from the expansion/fumes.
Is the tank only vented through the cap, or is it vented elsewere?