My 40/60 3/4hp shallow well jet pump will run continuously and will not build up pressure in the bladder. The bladder will hold pressure though. I have filled it with air and when I turn on the water it loses its pressure and when the pump kicks on it just keeps running without building the pressure back up. The pump will not shut off unless I fill up the bladder with air again. I have no visible leaks and I have tried to lower the pressure on the switch to no avail. Do I need a new pump?

Sounds like the bladder is leaking air.Shut down the system, drain the water from your tank,check the pressure in the tank,should not be much, 2-4 lbs. Turn system back on and wait till pump shuts off,60lbs. If pressure bleeds off, with no water use,Bladder is bad.

Your pump is the problem. When you put more air into the bladder, you are simply increasing the system pressure. When you add enough, the pressure gets high enough to cut off the switch. But once you turn on water, enough water exits the tank to lower the pressure. Your pump, for some reason, is not refilling the tank.

The bladder is not the problem. Even it is leaking, that would not cause the pressure to drop. The only purpose of the bladder is to keep the air charge separate from the water. But the tank would work fine for several months even if the bladder was not there at all.

Will your pump hold prime? If it does, then you are probably looking at getting a new pump. Of course, it's possible that the water table has dropped enough to be causing problems as well.

Is it possible your pump has lost its prime? Have you checked that?