I am wondering if this could be the result of some interesting/incorrect plumbing of my shallow well jet pump. I will be trying a new pressure switch but I have an interesting pipe that runs from the outlet side of the pump back to the inlet side of the pump before the check valve. There is a valve on that pipe and it has been open since we bought the house 2 years ago. I haven't tried closing it. I figured someone put it in for a reason but I can't figure out what that might be. Any ideas? It's the blue pex pipe in the photos.