partners suburban is down again the fuel tank selector assembly cracked so she had it bypassed. now there's lots of air getting into the system somewhere. I suspect that the person who did it used fuel line that is too darn large and it isn't sealing properly. so, what diameter is the metal line that the rubber ones go over and clamp down? or... what inner diameter do I need to get since I think I'm just going to replace the rubber with tygon?