Sprinkler pump prime

[JBH46]

After replacing a broken fitting just at the water line on a lake fed sprinkler system and then replacing the pump I have not been able to get the pump to maintain its prime. The system has about 50' of pipe from the pump to the lake and another 30' of pipe underwater to an intake screen. Not knowing where the old check valve was located underground, we installed a new check valve within a couple of feet of the intake screen underwater. Now the pump will not stay primed. It loses almost exactly 1/2 gallon of water within an hour or so after running and always this same amount even after a few days so will not re-prime itself. Does the consistent amount of water loss to re-prime give me a clue that a leak is likely in the system near the pump?

 

[Reach4]

If you tied a loose plastic bag around the screen, and that bag filled with water , then you would know that the new check valve was leaking.

I don't think the constant leak rate gives you a clue.

Any chance you could switch to an underwater submersible pump? Those require wires, but there is no priming required. Bonus is they are more power-efficient, so less HP is needed for a given water flow. Some worry about electrical shock issues. I think that could be dealt with. I am not a pro.