Truck Forums - Power steering issue!

The power steering pump went out on my 2000 Seirra 1500. The shaft and pulley was sheared from the pump. I have replaced the pump but still don't have power steering. I have confirmed that it is pumping thru the system. I followed the basic procedure for bleeding the system, but it shows no improvement.What else could be going on? The truck has been driven for a few days before I replaced the system. Is that an issue? Does weather play a factor? It's very cold where I am right now. I am at a stand still. Help please!