No power steering

[Ricks90billblass]

I'm out with the wife the other day, dropped her 06 Stang at the stealer for warranty work. Off to breakfast (She's buys since she dragged me out of bed to get to the dealer by 7am.) And as I pull in the lot the steering gets REAL hard like I lost the pump. I checked the fluid and it is where it should be, belt is on too. After breakfast its back to normal, next stop Ford recycler yard same deal. Later it gets to the point that even shutting off the motor doesn't help. I'll try in the morning to see if I have P/S again
Any Ideas or Similar experiences?
In 1998 I replaced both the pump and rack to put in the LSC unit. (Mines the Bill Blass.) A couple of years ago I replaced the pump to fix a leak.
Thanks, Rick
UPDATE: Started my car up after over night. No power steerig at all. Pully and pump shaft both spin.

 

[Elessee]

assuming you don't have flat tires.. there's no mechanical damage to suspension or steering components that prevent wheels from turning...

From the '88 LSC Manual,
Steering System diagnoses..

Heavy steering efforts, Poor Assist, Loss of Assist:

Low pump fluid. (warm it up, turn wheels to both stops once or twice. Check level.)
Gear assembly external or internal leakage. (rack and pinion needs diagnosis)
Pump external leakage.
Improper drive belt tension.
Hose or cooler external leakage.
Improper engine idle speed. ( i guess they mean too low to develop enough pressure)
Pully loose or warped.
Pump flow / pressure not to spec (They stick a flow-pressure meter in the line to test them.)
Hose or cooler line restricted. (something prevents fluid flow)
System contamination. (says look for foreign objects, kinked hose.. something's blocking flow.
Plugged valve screen. (a screen inside the pump.. again, fluid flow is blocked.)
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..and each component has it's own diagnostics pages..
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I never had steering problems .. except a whine, but that was from air in the fluid. I got that by turning the steering wheel with engine off several times (while working on the front suspension).
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[edit]
As an after thought, i'm thinking you might loosen a fitting somewhere and see if fluid is flowing (pouring out). Maybe try it at a few different spots.. (Flow should be near 6L per minute. 25 cups.. about 1 cup every 3 seconds if allowed to flow freely.)
Might even hook up a pressure gauge to a line if one's laying around. (pressure is about 1,000 psi)

 

[Ricks90billblass]

Thanks, theres some food for thought.