I am having problems adjusting my pressure switch on my jet pump. I adjust the cut in and cut off just enough to keep the pump running until the demand is off. But sometimes the switch keeps kicking on and off and won't stay shut off. The air bladder is adjusted to 2lbs below 30 pounds kick on pressure. There are no water leaks in the lines. Shouldn't the pump only come on when the pressure drops to 30 lbs. and shut off at 50 lbs. ?

There is only one adjustment screw because it has a fixed differential. A 20 lb differential is standard. I recommend a 40-60 pressure setting which gives you an average water press of 500 psi. With a 40 cut-in, your tank pressure should be set at 38 psi. There is a schrader valve at the top of the tank. Use a tire gauge to set it at 38 psi. Do that first. Now set your press switch by running water and observing at what pressure the pump kicks in at. Don't worry about the cut-out pressure. It's trial and error.
Let the pressure build up above 45 psi and then run water until you hear the pump kick on. Keep doing this until the pump kicks on at 40 psi. It may take a few tries, so I recommend having someone else turning the water on and off for you.

The water pressure is adjusted with the pressure switch, which turns the pump on and off. The pressure switch is typically set for a cut-in and cut-out pressure of 20-40 psi, or 30-50 psi. Usually there are adjustment directions on the inside of the switch cover. But, there are several other factors that may affect the house pressure. If there is a pressure tank that is pre-charged, the tank pressure may need to be reset, or the tank bladder may be ruptured. Have the entire system checked out.

There are two adjusters, one for max pressure, one for the difference between cut in and cut out. If you have fussed with either of them, look on the old switch for an idea of where they belong.
Basically, the one on the big spring is tightened until the pump cuts off at the desired pressure, and the littler one is just tightened up until it is not loose.
Further adjustments have to be made in small increments, with the pump allowed to fully cycle up to the desired pressure. Then the pressure has to be released (let some water out) until the pump comes on.
Balancing between these two adjusters is not easy.
If you have totally messed up, get a new one and don't mess with it. It will be factory set to the settings on the box.
If the pump still won't stop running, you have something wrong with the plumbing, like a check valve that has failed.
The foot valve is the most likely suspect to fail. If there is no foot valve, there should be a check valve on the suction side of the pump.

There are several causes for this to occur.
1. If it is a 20-40 switch right out of the box it may not be set correctly. I have had this happen. If it builds to 30psi and shuts right off without straining to build to 40psi adjust the Cut-Out pressure up to 40psi. There are two different adjustments on a well switch. One for Cut In / Cut Out psi and one for Cut Out psi.
2. Lack of head pressure being built by the pump can be the cause. This can be attributed to the wrong Jetting in the pump. IE: A shallow well jet/venturi on a deep well.
3. The pump may have a bad impeller, but the pump will generally really strain to build pressure and a bad impeller will be loud, like grinding at times.
4. Double check the pre-set pressure in bladder tank also.
RJ

The nut on the larger spring in the pump pressure switch: Usually the larger nut in the pump pressure control switch adjusts the pump cut-on ("cut-in") AND pump cut-off pressures simultaneously. This is the left-hand spring (and nut) in our photo. That means that whatever the gap is between the cut-on pressure and the cut-off pressure, that gap is maintained, but the entire operating range of the pump is raised or lowered. Turning the large nut clockwise RAISES BOTH the cut-on and cut-off pressures. So turning the large nut clockwise shifts the whole operating pressure range of the pump UP to HIGHER pressures.
Conversely, turning the large nut counter-clockwise will lower the whole pump operating range. This is the simplest adjustment to make.
Photo (left) courtesy of a reader.
The nut atop the smaller spring in the pump pressure switch: this nut is used to narrow or widen the gap between the pump cut-on and pump cut-off pressures. This is the right-hand spring (and nut) in our photo).

Turning the small nut clockwise (tighter) will RAISE the CUT-OFF pressure, and vice versa, loosening or turning the nut counter-clockwise will lower the cut-off pressure. Watch out! If you loosen this nut too much you can set the cut-off pressure below the cut-on pressure and the pump will turn on and run forever (or until it burns up.)
Which nut to turn in the pump pressure switch control, and which direction to turn it, are usually visible on a label inside the pressure switch cover. Above we show photos of a common Square D water pump pressure control switch (Schneider Electric) and the label with pump control adjustment details. [Click to enlarge].
Here are Example Pump Pressure Switch Adjustment Instructions from Square -D Understanding how pump pressure control switches work and which way to turn which of the two nuts in the control can be confusing.
On a Square-D Pumptrol® 9013FSF-2 pump pressure switch, for example, Square D tells us that we

• Turn the Range Nut #1 (the larger spring and nut) clockwise (to the right or "down") to raise [both] cut-on and cut-off pressures. This is "tightening the nut down" against the spring. ("Rightie-tightie, leftie-loosie" as Mara Gieseke says to her kids). Thanks to reader Rise for this clarification.
  
  In other words, adjusting the pressure on this spring shifts the whole operating range of the switch up or down, but keeps the difference between cut-in and cut-out the same, whatever it happens to be (typically it's about 20 psi from the factory.)
  
  If you want the pump to turn ON (cut-in) sooner, that is, at a higher water pressure, turn the nut clockwise or "tighter".
  
  If you want the water pump to turn ON (cut-in) later, that is, at a lower water pressure, turn the nut counterclockwise or "looser".
  
  
• Turn the Differential Nut #2 (the smaller spring and nut) clockwise to raise the cut-out pressure.
  
  If you want the water pump to turn OFF (cut out or cut-off) at a higher water pressure, turn this nut clockwise or "tighter".
  
  If you want the water pump to turn OFF (cut out or cut-off) at a lower water pressure, turn this nut counter clockwise or "looser"
  
  Here is why the small nut is called the "Differential"

Keep reading at LINK

Make sure the foot valve in the well is good and the ejecter is cause I have replaced some with a pin hole in them or a rock get in foot valve and not let it hold pressure right.

Pressure Switch the big screw should be the only one you turn to adjust pressure increase or decrease if you moved the small on eyou can look at your old one to get an Idea of where it was set or get you close.

If the pump cuts off at 30psi the pressure switch needs to be adjusted. Take the cover off and turn the screw clockwise until you get the pressure you want. I like 60psi on mine. If the pump don't cut off, just runs and runs the bladder in your presssure tank could have a hole in it, or you could have an air leak or the bladder needs to be pumped up. There is a valve on the tank like a tire valve and it needs to have air in it. I think it is supposed to be half of the cut out pressure. If it was working ok before I would check this first, that might be all you have to do.

There are tow screw adjustments on the switch. One is the high shut off and the other is 'differential'. This is the one you need to adjust. It gives the 'window' that the system needs 'between' on and off.

If you need further help, I’m available over the phone at https://www.6ya.com/expert/craig_3fa289bf857b1a3c

Hi, W/D here.

To accurately test a switch, it has to be removed from the compressor and tested by raising the pressure and lowering it with air supplied from a known, good regulator. The trip pressures are then noted and adjusted.
The quick and dirty way of "getting close enough" is a little different. Start the compressor, and when it gets to your desired cutoff pressure, pull the plug. Adjust the HP spring untill the contacts trip out. Now, with the compressor still unplugged, drain the pressure off of the tank until you reach your desired cut in pressure, and close the valve. Adjust either the LP cut in or the differential pressure adjustment to set the cut in pressure. The contacts will pull in. If you adjust the cut in pressure with the diff pressure setting, the cut out pressure has to be challenged and set again. Whichever method you follow, you always need to check the upper and lower settings after each adjustment.
Best regards, --W/D--

You have a defective pressure switch.But replacing the switch. Do the following; Open the pressure switch cover, and find the two adjusting nuts. One is for the cut-off pressure (40psi) and the other is for the cut-in pressure (20 psi). Adjust the the nut with a longer stem counter clockwise (loose) with the pump running. Take care not to touch the power line attach
to it. Continue the adjustment until the pump stops,
at 40 psi. Then, observe - Pump must stop once the
pressure is attained. Then, open the valve until it
start (20psi).. Then you can adjust the other nut to
cut in at 20 psi.
To prime the pump; open and fill the priming port full
with water.and replace the priming port plug. Set
the water flow control valve at full close position.
Switch the power on to run the pump and slowly
open the control valve to appropriate setting such
that the pump doesn't lost the suction. Send your e-
mail for further comment. God bless u