Wondering if it is possible for a pressure tank to have too much air in it. I have a water well at our cabin which has an older 1/2 hp sears jet shallow well pump on it. We recently put a new 50 gal pre charged bladder tank on it. Since then, the pump does not want to turn off and looses its pressure very easily. It will raise it pressure within 4 seconds after being primed. But once it gets there it keeps running (not increasing in pressure, just maintaining it) . Even with the shut off valve closed it will continue to run. It has excellent pressure when it is running but looses its pressure with 5 minutes of use. There does not appear to be air in the line after the initial starting it. It just looses its prime after a couple of minutes. The tank it self does not seem to have water in it when tap on it, just wondering if the pressure is to high. The tank does have a pressure gauge but it is broken. How do I measure the pressure on the tank to compare to the pressure switch. If it is the wrong setting, how do I correct it (by letting air out of the tank or by increasing the pressure setting on the switch) would this also cause it to continue running as well. It continues to run but does not increase in pressure, the pressure will stay steady or decrease with use. Could this be a switch problem, if so is that hard to switch out. When I prime it, I remove the cap fill it till it burps, then close it back down tight. Do I need to leave the cap off a see how the water flows? People talk about draining the water out of the tank, how do you do that. Thanks

It would appear that you may have a number of problems. You tank may or may not be properly charged, the ports of the pressure switch and any tubing leading to may be clogged.

I suggest that you first turn off the pump and empty the tank of all water. Check the empty tank air pressure. The pressure should be 2 lbs below the pump cut-in pressure. You really should obtain a new pressure gauge, they are not that expensive. In the mean time you could check the pressure with a tire gauge. If you don't know the cut in pressure, set the air charge to 28 lbs. Remove the pressure switch and make sure that it is clear of debris. Also clear any piping or tubing. You may have to replace.

Turn pump on and let it run until it turns off. Check pressure with tire gauge. Open faucet and let tank drain until pump comes on again. Check pressure. You now know pump cut-in and cut-out pressure settings of pump control switch.

Turn off pump, drain tank and reset air charge of tank to 2 lbs below cut-in pressure if necessary.

With these things out of the way you can now address any pump/well problems you may or may not have.

How do you drain the water from the tank. Would that happen on its own when the pump looses its prime, or is there a valve that I open to drain it. I am going to purchase a new gauge and swap it out. Is it tricky to take the pressure switch off and clean it or is it pretty straight forward. I am guessing that I would do this at the same time that I change out the gauge ( after the pump looses its prime)

To drain tank just turn off pump and open a faucet. The air pressure will push water out of tank. Let air out of tank before removing old gauge. The pump switch and the gauge should just unscrew. The pump switch may be on the tank or the piping. Just unscrew, clean or replace. Use pipe thread compound or Teflon tape on threads and reinstall. These fittings are usually brass and do not require over tightening.

Sounds great, I will try that this weekend. Could this be a problem with the pressure switch being higher that the pressure in the tank which prevents the motor from kicking off.

If the pressure switch or the tubing or pipeing to it are clogged the switch doesn't know what the true pressure of the tank is. Therefore it doesn't know when to switch the pump on or off. The gauge only tell you what the pressure is.

Sounds like a pressure switch problem for sure.What I did at our cottage,we have the same set up as you, I set the tank pressure while the pump was running.Take off the switch cover and you will see a set of contacts,looks like points on an old distrubutor.Prime and start the pump and when it gets to 28lbs turn back the screw on the contacts,the pump should turn off.Youwill now have 28lbs working pressure witch should be suffeciant.Get you wife to turn on a fawcette and watch the pressure ,it will drop and at a set prussure it will kick back on to bring it back up to the 28 lbs working pressure.I can't remember what I set my kick on pressure at but 18 seems to come to mind.If the pressure is set to low the pump mite loose its prime causeing the pump not to climb back up to the set 28lbs.Also make sure your foot valve is in good working order,I remember working on my pump half a day just to find out my foot valve was toast,lol.I sure hop this helps,if I can remember any thing else that mite help ill get back to you, good luck.

Is the foot valve on the very bottom of the pipe going down in the well. I guess I would have to cut that pipe in half and lift it out to check it? Also would it have excellent pressure when it does run, if it had a clogged or blocked foot valve?

The foot valve would be right on the end of the hose that suplies the water to the pump.If the foot valve is leaking you would have a slow or fast loose in pressure,depending on how bad it leaks.Not good to have the foot valve leaking back,it cause's the pump to run more often then need and hence you have premature wear on your most expensive part,the pump.You would have excellent pressure even if the foot valve leaks,the foot valve is only there to prevent the water in the line from draining back into the lake or well hole you have.Pull the line out and you should be able to see if its leaking.Dry it off 1st.
Ill insert a link to show you a pic of a foot valve,haven't gotten around to figureing out how to post a pic yet,lol.
Rittenhouse | Foot Valve - 2" Brass (http://www.rittenhouse.ca/asp/Product.asp?PG=1525)