I have a well and pressure tank, when my pump fills my pressure tank I have a loss of water or pressure within 90 seconds and the pump runs again. I have closed the valves on the water heater and the valve at the pressure tank. I still have the same 90 seconds or so cycle. Any suggestions?
Depress the air valve stem. If water comes out, you have a defective tank. Otherwise you shuld be able to repressurize it. In any case pressurizing it with water in the system will get you by until a new tank can be installed.