I just replaced the electrical switch on my water pump. When the pressure gets to 40 psi the switch keeps flickering on and off at a fast rate. Does that mean I have a bad switch and need to replace it again?

We had a situation on this board similar to yours a year or so ago. Found out it was due to something similar to water hammer caused by pumping into two pressure tanks. Is that your case?

When you installed the new switch, did you replace/clean out the little pipe leading to the switch?

What was the problem with the old switch?

Always a good idea to check your pressure tank. Depress the air valve at the top for a few seconds. If water comes out, then the tank is shot. If the tank is good, then turn off power and drain pressure through in outdoors faucet until pressure gets to zero. Set the pressure at the top of the tank to 2# BELOW the cut in pressure.

Just giving you some simple ideas before you replace the switch. It would be frustrating to put on a new one only to have the same problem.

Is 40 lbs the cut off setting? What kind of tank, pressure or bladder?