I've had problems daily for 2 weeks with my water pressure dropping to almost nothing for a few seconds to a minute or two on the outside faucet but not inside the house. I've only had a drop in pressure twice inside the house and only when several things are running at once. Outside it cycles like this several times during garden watering. We have changed the pressure switch. The new switch will turn on but soon kicks off and stays off. The pressure gauge seems not to be working. Will the gauge not working cause this type of activity? I have a.O Smith Aqua Air V250 tank and I'm not sure where to look for a pressure valve to check the air inside the tank(not on top of the tank that I can see). Does anyone know where else it might be? Also any suggestions on my next step? Thanks

The V250 is a large bladder tank. You should have long cycles, meaning periods of water use between the pump cutting off and then back on. If your cycles are short, which you seem to be describing, you would look first at several things.
1. Find the air valve at the top. See the link below to locate it. Press the valve a few seconds. If water comes out, then your tank is bad.
2. When you changed the switch, did you inspect or replace the little pipe leading to the switch? These can become clogged and make the switch sluggish to respond.
3. Could be a leaking checkvalve, but it's hard to say without a working pressure gauge. Replace the gauge, then see if pressure holds when the pump is off and no water is being used.
4. The gauge will not cause your system to malfunction.

OK. Now I'll post the link I forgot to post above.

http://completewatersystems.com/wp-c...04/HPTANK2.pdf