I have a drilled well that is 80 feet deep, and a two stage jet pump, my pressure seems to be good, but it doesn't maintain the pressure for more than a minute. I have pulled up the line and changed the foot valve, and my bladder has 18psi when dry. What could be the problem I am not seeing? There seems to be no leaks that I can see could you also tell me what the valve screw at the top of the pump should be correctly set at? Any answers would be of great assistance. Thanks!

You have a leak some place. Since you don't complain about losing prime I assune it's on the pressure side. Either in the house supply on in the house itself. What do you think? Tom