Whilst trying to cure a problem on the Sprint a fuel tap rebuild was part of the process

The T3s have a vacuum operated fuel tap...a tube connects the the vacuum take off on the carbs this creates a pulse that operates a diaphragm which sucks the fuel through..there is no OFF position on a vacuum tap there is prime, reserve and on, the diaphragm acts as the off position because if the engine isn't running then there is no vacuum pulse from the carbs..

The taps can cause the odd problems and with aging carbs the possibility of fuel leaking past the tap and then past the carb valves is not a good one, my bike was over fueling and pulling the fuel tap apart was one of the many things I did to try and cure it.

Sprint manufacturing sell a fuel tap rebuild kit, after removing and draining the tank only two bolts hold it in place



It's pretty straight forward pulling it apart





You can see the black diaphragm in this one



You will need to pull the old one thought the hole and gently feed the new one in



Two screws retain the selector



You can then lever out the seal



Now you can see the tap part of your fuel tap...



Replace the parts that are in the kit as you go along...tap in the new seal



One very good tip is to use some Araldite in the recesses on the revers on the fuel tap selector wheel, they nearly always break and this is the cure