I have just installed a new 36gallon pressure tank because my old tank was bad. I also put a new 40/60 pressure switch and gauge in. I put 38psi in the tank and turned the pump on but I am only getting 28psi on my gauge and my pump is running non-stop because I am not getting enough pressure to get to the switch to cut off. What may be the problem?

Is this a submersible pump or a jet pump (above ground)? I am assuming you did not have this problem before you installed the new tank?