Are foot valves prone to stick shut randomly?

[Carl_NH]

The vacuum from the jet sucks the water thru the valve and when there is constant draw down (vacuum) the lift of the valve is steady.

On the occasion you draw water intermittently turning on/off the hose when the pump is running, the valve will "flutter" without the spring keeping down pressure, and if at that time it is near shut down it wont seat properly and leak down.

Most of the time it will seat without the spring down pressure on the check valve, but not always, depending on the flow at that time.

 

[DFB]

I believe the explanation is he was losing pump prime from water leaking past the footvalve because it wasn't sealing off tight. Then upon startup the pump was just sucking air instead of water.

How to prime the well pump; How to Diagnose & Repair Repeated Loss of Well Pump Prime

I see Carl_NH covered it well lol

The link has a good diagram