I need help identifying the three fuel lines on my 2003 Ninja 250?

I have a 2003 Ninja 250. When i take off the seat, there are 3 fuel lines, and the one on the left is cracked. I can%26#039;t figure out what that line is for. A small amount of fuel vapors come out when i%26#039;m running it, but no fuel pours out when i%26#039;m running with the tap in any position. What is this line for, and how urgent is it that i get it fixed? Thanks|||It%26#039;s probably a vent line and the three being supply, return, and vent.