is priming the answer? . I fitted a short lengh of pipe to in inlet side of the pump to a small tin of fuel and lo and behold it worked ok , I refitted the original pipe and it still works ok !! . I don't have any other answer . Is it just one of those things!!
Regards Phil
Don't know what your problem was, but the SU pump doesn't need priming -unlike some high pressure pumps for fuel injection. It should chatter away pumping air until the fuel finds its way into the pump. Having said that I don't know what height it'll pull fuel in from, I think the only spec is the output pressure. Maybe it'll manage sucking air and then fuel from the tank to the carb but not from a can on the floor up to a garage bench?
Well (!) - no pump will suck more than 1 atmosphere = ~33 ft for water !! But it will only suck if the valves are ok - if they are dry and perhaps a little bit of dirt in there - the priming with fuel may just have lubricated/cleaned them enough.
The valves certainly can fail. My car was fitted with an after-market electronic pump when I got it and I had to replace it due to a split in one of the valve diaphragms. Maybe with an SU pump you can get spares for the valves?
