Run water until the pump starts and note the pressure. Shut off that water and note the pressure when the pump shuts off. The readings should be something like 30/50 and that's your pressure range. Then you need to drain the pressure tank and check the captive air pressure in the tank. Shut off the power to the pump and the water to the house before draining. Then adjust the air pressure to 1-2 lbs less than the lower number. I.E. 30/50 gets 29-28 psi air pressure with no water in the tank.
If you get water vapor or water out of the tank when you check the air pressure, the tank needs to be replaced because that indicates a broken bladder.
Quality Water Associates