I have a Gould jet pump that I have been using several years to pump water out of a river for irrigation and adding water to my pool. Now I cannot get much pressure. If I run the water straight through the hose, I can maintain about 20 psi. I used to run about 40 psi. It does not use a pressure tank. If I hook it up to a sprinkler, giving resistance to the line, the pump will lose prime in about 10 minutes. I installed new piping and a new foot valve. Could this be a problem with the pumps diaphram? I took the pump apart and the diaphram seems okay but is not very pliable. Like an idiot the pump sat outside all winter in New England and I wonder if the cold affected it. Anybody have some ideas...I need to water my maters.