fresh water pump runs but won't prime and push water

My older trailer has the winterizing hose with a valve right next to the water pump. I did not have that valve closed enough one time causing the water pump to suck in air instead of prime water from the fresh water tank.

Kinda like this pictorial...

Google Image

I have used this winterizing tube a few times to check out pump by sticking it down a bucket of fresh water for testing... Works good me me doing this...

When I have problems like this I always think back what I did last haha... Most of the time it was self inflicted hehe...

Roy Ken