My jeep does the same thing, but not all the time, I think my pump is just crapping out. Like I said it isn't all the time.

Does it make any noise? Does the fluid smell burned?

 

no the fluid is not burnt, its a new pump and new hoses.its fine when you are driving but when you go to parrell park you cannot turn the wheel unless you rev the engine up in park or netral.if you are stop you can not turn the wheel or very little. i bled the system again today. anybody any ideas. this truck is starting to tick me off

 

when the vehicle is in the air and your trying to bled the system, is the vehicle suppose to be running when your turning the wheel back and forth or should it be OFF when your turn the wheel. JUST TRYING TO FIGURE OUT THIS PROBLEM AND TRYING TO ELEMENATE THINGS, THANKS GUYS

 

i find when the power steering is cold it works fine but as soon as it heats up to operating tempetures it becomes hard to turn.what could cause this???????????????????

 

if you have reached thelimits of your mechanical knowledge, pay a dealer to diagnose it. easiest and fastest way to get an answer

 

bad pump, still...

 

Sorry I couldnt get back with you earlier.
Most shops do not bleed the power steering with vehicle in the air.
Try this, may take 2 or 3 times. A little different than the previous link. Sometimes vacuum IS neded to remove air from the fluid.If this does not help, you may want to change manufacturers on the power steering pump.
Refill the reservoir as needed. Cap off while bleding only. If fliud runs low and ANY air gets into system you will have to start over.
1. When the fluid is warm, turn the wheel slowly from lock to lock. very slowly and All the way. This will create higher vacuum and will help push air out of system.
2. Turn off vehicle and check fluid. repeat step 1.
3. Test drive the vehicle. If there is any niose (groan or other), or you are still having problems with full turningair is still in the system. Check for leaks and repeat steps 1 and 2.

As i stated earlier, doing this while vehicle is warm and doing full turning from side to side will create more vacuum.

Kinda like bleeding your brakes, the more pressure you add the more air will come out.

Good luck