I had a short well pump cycle problem, with the help of here, I have the new pressure water storage tank installed by the plummer 3 weeks ago. However, now I noticed that my pressure control is 40-60psi, so when the pressure dropped to 40psi, the pump didn't start, it will suddenly plummet to 20 psi, and then zero while I have no water of course at this moment. Then a few seconds later, I can hear the pump kicked in and the pressure jump to 40 psi immediately and gradually increase to 60 psi like normal and stopped.

Right after the new water tank installed, it happened that the pressure gauge will plummet to 20 psi from 40 and then back to 40 psi. The plummer think it was clogged/bad pressure control so he replaced that piece two weeks ago. It seemed to fix the problem at least when he was there. After that I didn't go check until we have run out of water for a few seconds last week.

Could some body help me with what could cause this ?

Thanks a lot.

If you shut the pump off at the breaker w3ill the pressure bleed off to zero?
Did the plumber check the little tube that runs from the pump to the control box?
Regards, tom

Good questions from SB. Also, make sure the pressure at the top of the tank is set 2# below the cut in pressure. So, if your cut in pressure is 30#, you will set the tank to 28#. Turn off the system, drain pressure by opening a low-level faucet, set the pressure to 28# (or whatever is needed in your situation), then turn the system back on.

I haven't tried to turn pump off yet. Will try it tomorrow. Will also check the pressure tank.

Just tried to turn off the pump, the symptom is the same. From 40 psi plummet to 20 and slowly to 15psi when I stopped the water. I turned on the pump, nothing happened for half minutes, so I turned on the faucet to allow water pressure drop to close to zero then my pump kicked in. So what that means? Thanks !
BTW, the plummer only checked the pressure control. I am not sure what the little tube is. Is there a name for that?

The little tube refers to a small 5" long or so pipe that screws into the back of the switch. It has a bad habit of clogging and preventing the switch from working properly.

SB wanted you to allow the system to pump up to where the pump cuts off, then see if the system will hold that pressure with all faucets off.

Also, check your tank as I described above, then get back with us.

Oh, that is what you guys mean. The pressure will hold on to 60 psi until I used the water. That little tube looks like being newly screwed to the new controller. So I guess the plummer did clean it before he changed controller. I have called the plummer back. Will ask him to check the pressure. Thanks.

See if this describes your situation. The pump goes to 60# and stops. As you use water, it slowly drops to 40#. At that point, the pump is supposed to kick on. However, the pressure suddenly drops to 20# or so, then quickly recovers to 40 and pumps back up to 60. Then the cycle goes around again. Does that sound right? If so, then your problem is more than likely going to be found in the tank setting described above.