How do you prime a windshield washer pump?

If you have a newer vehicle with a pump motor at the bottom of the reservoir the head pressure of the washer fluid above the pump will prime the pump. If this is not working then you may have a bad pump or some form of debris is blocking the inlet. Some older vehicles had a pump that was mounted above the reservoir fluid level and a stand pipe that would siphon the fluid and these could crack, fall off, get plugged or blocked the same as the above pump inlet. If you can hear the pump motor working (e.g. a whining sound) and the water level is not going down, check the inlet for debris or check the stand pipe (older vehicles). I have seen, only once, where the outlet from the pump was pinched and not allowing fluid to pass. I suspect that the pump was leaking internally though because they are positive displacement pumps and will usually burn out or blow the discharge tube of the end.