In understanding your fuel system, there is no need to turn the valve on and off
unless you are working on the carb(s) as the system is a pressureized one that
the Fuel Bafel breath line can breath in or out and regulated by a one-way check
valve after it branches, that opens at 3-5 lbs psi. Opening the gas cap lets any air
pressure escape and that depressurizes the gas tank delivery system. A large expell
when opening the cap also means the out valve that vents under the rub rail is cloged. We recommend replaceing selector valves with a plastic one, or if cleaning
your existing, to dill out the three tubes on valve with a 3/16" drill. Bills86e