2002 trans am steering issue pls help...

I have replaced my rack and pinion 3 times and my pump 3 times and the car hasn't been able to drive down the road. I do as the manufacture is suggesting and pulling a vacuum on the pump at 20 in hg for 5 minutes and on top of that I have flushed the system changed the lines everything. If I have the front end in the air It has no problem however when I let the tires touch the ground and try to steer the pump locks up and I get a load noise and a loss of steering. When I shut the car off and restart it it will work fine again until I turn the wheels and it locks up. Im stumped I have swapped all the components 3 times unsure of the failure. Any one have any ideas thanks.

Have you inspected your power steering hoses to see if they are collapsing while the engine is running or while you are steering the car?

I have and I replaced them everything is completely new. So today I found my issue and was able to drive the car. The issue was I was using oriellys parts. I found that after removing the pump this morning and taking it apart the shaft that the pully goes on had no snap ring holding it in position and allowed the gears to bind up and stripped the gear on the shaft. I used the 2 failed pumps and built 1 good one. I didn't want to get another pump from any were. Last night I removed the high pressure line and found that the check valve in the rack had come apart so I put the third rack in. I still had the same issue. This morning waking up furiously I removed the pump and rebuilt the pump myself and it now works. I don't understand why it is so hard to get quality parts from the auto parts store anymore.

relieved and thanks for the responce

Ugh. Sounds like a complete nightmare. I have always said that "new parts" do not necessarily mean "good parts". Glad you got it figured out.

Sounds like someone in their Quality Control division is asleep. How someone could half-ass rebuild a pump is beyond me.