All Street 500/750 Have Defective Fuel Pumps
The manager at my dealership told me it is a problem with a clip that sits at the bottom of the pump. It holds a rubber grommet in place, but it is poorly designed and it sticks out just a little bit, the pump sits off to the side, so they are thinking that if you put the gas pump all the way in it is hitting that clip and bending it, which then damages the grommet; letting air in.
A new pump is supposedly being designed, so they same bad pump model has been put in my bike again.
All owners need to NOT put the gas pump all the way in. I am also concerned with this clip holding up on long rides.