Originally Posted by JRWooden
I was told that the valve was not supposed to "vent" until a certain threshold value was exceeded on EITHER side of "atmospheric" pressure -- both to the high side (some number of psi above zero-psi-gauge pressure) and to the low side some number of psi/inches of mercury below zero-psi-gauge pressure (i.e. a vacuum).
In other words there is a range of pressures above and below atmospheric at which the check valve does nothing and "holds" whatever pressure (positive or negative) that is sees in the tank.
did you disassembe the thing?
there is a ONE-WAY (including the arrow) valve on a rubber hose under the back edge of a seat... it can only pass air TO the tank.. ale least on my bike (5/2008).
when you hear a hissing sound when opening the tank on gas station -- it's gone.
I have personally second one.. + one repair done by myself with help of air compressor (it was simply stuck).