I have a 1980 ford Bronco body sitting on a 1979 frame.  I have changed the power steering gear box, steering shaft, and pump.  It is 4 wheel drive with a 351m motor, a 3 inch body lift, 35 inch tires, and a locker in the rear axel.  I don't know if that has to do with my problem or not but I don't have any prower steering.  Is there anybody out there that can help me find the problem??   

Have you checked your power steering lines ? Maybe one is pinched or blocked by an obstruction inside the power steering line. Be careful with power steering lines - there's a lot of pressure in these, and it can be very dangerous if you don't watch what your'e doing.

Check your high pressure line going to the steering box and make sure it is not blocked. Then bleed the system of any air. Does the pump make a lot of noise or is it not working at all? If it works intermitantly and the steering wheel kind of hops when you turn it , it is probably air in the sytem.  

I have checked everything.  All my hoses are flowing freely.  I have pressure from the pump but no power .  It doesn't make any noise when trying to turn, it has power once in awhile when I turn to the right but not allways and never to the left.  

I have run 3 quarts of power streeting fluid tru it trying to bleed it.  Still nothing.  

I had the same sort of problem on my 78 Ford Bronco. I changed the power steering pump,gearbox,tie rods,draglink etc etc. It ended up being the steering linkage. The rag joint was shot. Everything was so stiff and hard to turn I was sure it was the pump or gear box.I put in a borgeson shaft with the u-joints on it and haven't had a problem since.

Just a thought, you may have checked this already.

Went thru the same too. My problem wound up to be bad O rings in the orbital valve.  

I am having the same problem,  I am not familiar with the orbital valve.  Is that in the steering box?