We have a 120' deep well. The bladder tank is good. Just replaced the pressure switch. The house water is okay

but when I turn on the outside water hose, all water drains from the bladder tank and the water runs out.

The pressure switch runs the pump constantly till it gets hot and shuts down... or the pressure switch never comes on and when the bladder is empty, I have to shut off the power and start it again. We have not replaced the check value. Any clues?

If I wanted to be a smart_ss, I would suggest that you simply no longer use the outside spigot, but I imagine you are not in much mood for humor at this point.

Just to be sure, you are saying that you can run water from the house and have no problems, but you cannot turn on the outside spigot without the pump either running constantly to the point of overheating or simply not coming on at all? I am assuming that you then have no water pressure anywhere, house, spigot, or whatever.

First of all, you will not notice a bad check valve until the pump turns off. Then the water in the tank will simply drain back into the well. Doesn't sound like a check valve problem.

When you use water in the house, do the pump and switch seem to work properly? In other words, can the pump pump up to cut off pressure, then pressure in the tank drops as the water is used, pump cuts back on and gets up to cut off pressure, and so forth? If that is the case, then we want to consider why you only have problems with the outside spigot. BTW, what kind of pressure/volume are you getting in the house?

Sounds like you have a well volume problem. Is your pump submersible or surface?

Let say that you system is set up like this;
The cut in pressure is set at 40 lbs and the cut out is 60 lbs. and that the switch is also set up such that if the pressure drops to 20 lbs. it means that the pump is running but not enough water is being pumped to maintain the 40 lbs. cut in pressure. In other words your well is dry. The well is capable of producing enough water for normal use of inside fixtures. These have a reduced volume and shorted duration in normal use. The well is not capable of producing enough water to replace the greater volume of the hose bib, which may be used for a greater length of time.
If you have a surface pump, I do not know whether it has a thermal overload switch but I doubt it. If it did you would have to reset it before the pump would restart if it were shutting down because it got to hot. Turning off the power and immediately turning it back on would not restart the pump if it had over heated. You would have to wait for the pump to cool and that could be anywhere between 10 to 30 minutes. Then reset the thermal overload switch.

So, your well is capable of producing enough water for your normal inside use but less than what can flow out the hose. The pressure switch is shutting down the pump to protect it because it thinks the well is dry.

Open all inside faucets and I'm sure you will see the same thing happen.

Time to go deeper or be more conservative. Not what you wanted to hear I'm sure but...

I think HK is on the right track. Still, the outside faucet should run long enough for the pump to cycle at least a few times before pulling the water level in the well down low enough to have a dry pump. And even at that, if you use water in the house for an extended period, then at some point you would pump the well dry even then. I would suggest this. Turn on that spigot, watch your pressure gauge and switch, and tell us how many times the pump will cycle before you lose pressure and the tank is empty.

It is possible you might be able to put the pump (or foot) farther down in the well, depending on what kind of pump you have.

One more thought. When you replaced the switch, did you happen to check the little pipe that runs to the switch? If it gets clogged, and that does happen, then it can cause all sorts of strange events with controlling the pump.