Window washer pump runs but doesn't work

[IIA]

I bought a replacement window washer pump - a universal E6Q9 from ebay. It makes noise like it's working but no water goes in or out. I put my finger over the intake and don't feel any suction. I've tried reversing the wires (there are no + or - markings), confirmed I have the tubes on the correct sides, and checked the tubes for blockages, but nothing seems to matter. Any ideas short of just buying another model?

[jimrr]

prime that thing, pressurize the tank while pump running, get it primed.

[IIA]

prime that thing, pressurize the tank while pump running, get it primed.

Yup. That did it. I filled the tank to the top and it worked. .... feeling stupid.