Fuel leak

The line to carb has an elbow that points up toward trunk and the return side has a 5 1/16 nipple straight out toward front of car . I filled the car up with gas 2 days ago and it had a leak around the o ring and I got that tighten and it stopped but then it started coming thru vent hose at a solid run . I blew air into the vent hose and it stopped for a few seconds then started back up I am confused why when I tighten the lock ring that it made fuel come thru vent hose