I have three lines going to my gas tank. Two of them dump gas on me and one doesn't (if I disconnect the rubber part). I think the one that doesn't, "C", is the one that used to go to the charcoal cannister. How can I tell between "A" and "B" which is from the tank and which is the return? "B" is larger diameter, but "A" dumps gas on me from the tank side (I didn't notice which side the fuel was coming from with "A"). I'm installing my TBI kit and need to splice the fuel pump into the correct line from the tank. I have a carb right now, but there is a return line from the fuel pump.