water pump problem

Foot valve should not cause cycling unless the foot valve is leaking, that sounds like a waterlogged pressure tank. There  may be a leak in one of the pipes going down to the foot valve that has gotten worse. Checking for that means pulling the foot valve out of the well. Put the diverter valve back to its original position and try again. The diverter valve controls how much water is sent back down to the foot valve/jet package to bring up more water. A submersible pump eliminates this one variable. A defective pressure switch could cause the pump to cut off at too low a pressure.  It takes looking at the system as a whole to determine what isn’t working properly. 

Normal pressure switch setting is either 30/50 or 40/60 depending upon the size of the pump and age/condition of the plumbing. The air pressure in the tank should be slightly lower than the cut in setting on the pressure switch IIRC. 

if the pump shuts off, then the PRESSURE REGULATOR is doing it... If you get 30 psi and the pump is STILL RUNNING and wont reach 40 psi, then the pump has a problem.

All this discussion of set points, bladders, switches is all well and good but seems to be skipping over the point that you have NO water. Should be able to disconnect the discharge from the pump, manually close the pressure switch if needed and you should be pumping water. You said it’s primed, my guess is that it’s not actually primed. They can be a bugger. If you’ve got the pipes submerged in 40 feet of water as you say, and get the pump primed, you can pump water. That seems priority one. We had a rough time priming one time, seems dad had me pour water into the discharge and he cycled the power to create surges and it worked. “Old Indian trick” he said!