Pump Won't Prime, Issue with Strainer Basket Flapper?

[SallieL]

Our pump won't prime unless we manually add water to the stainer basket. The water level is always low when the we open the basket after the pump shuts off. We wonder if it needs a new flapper valve. This Grainger part might be the replacement, but our current part doesn't appear to have the metal piece (see our pics below), is that what's missing?

DAYTON Flapper Valve Kit for 5PXF4, 5PXF5 - 23AZ72PP26055650907G - Grainger

It's a 20,000 gallon underground pool.

 

[AftonJeeper]

I'm not familiar with that pump/strainer but it looks like the part you need. The hole and the way the material is cut looks like it would fit under the metal bracket with the screw clamping it down.

Could you post a pic of your underground pool? I don't think I've ever seen one.