Never took the hydroboost apart. I knew about the pressure valve, but I have talked to some others that said they used the stock pump IDK! Just trying to work out bugs. The pump appears that it never pumped fluid to the hydroboost, only recirculated it in the reservoir. I first took the return line off the hydroboost and got nothing out with the engine cranking over. I then took the pressure hose off the hydroboost to see if I had an air lock and cranked it over, no fluid came out. I then started the engine and still got no fluid. I surmised the pump is bad!!FYI, the hydroboost power steering pump is different than a regular pump. There's more to it than just having 2 return ports. The pressure relief spring is different, there is an extra spacer on the pressure valve, and the orifice is sized differently for extra flow. And I had a pump years back not pump fluid no matter what I did. I found I had left the magnet out inside the pump, didn't think it would have anything to do with it, but I put the magnet back in, and the pump worked flawlessly afterwards.
As to the hydroboost pulling the pedal down, did you rebuild this hydroboost unit or open it up? The accumulator wouldn't cause any of these issues, it's only there to supply 1 or 2 applications of the pedal with power assist with the engine off. Now if you opened this hydroboost, you may have not gotten the spool valve installed properly, and it's boosting when it shouldn't. There is a fork you have to install in the spool valve correctly, if not, it will boost all the time. I've done a few of these now, and it's a job that requires patience and paying attention to get done right
IIRC WW had bad reman power steering pumps take out the entire system. Dusted it with metal shavings
You will need to check the oil in the system now for debris.Advance. It has a warranty
I run them on both return lines....You will need to check the oil in the system now for debris.
I run a filter on the return line from the PS box. (A filter on the hydro-boost return can be a restriction that keeps the brakes applied.)
Old School I guess...
The 3/8" MAGNEFINE filter extends the filtration spectrum to provide dual filtration that is designed to be completely effective in removing damaging ferrous metal particles from automatic transmissions and power steering systems.www.magnefinefilters.com
IMO There is only 2 ways to get a working PS pump. Virgin NEW or out of a junkyard from a clear wrecked vehicle. A wreck was running at the moment of impact so the odds are better that the PS pump worked at the time.
Repaired, rebuilt... aka repainted broken scrap metal that isn't fixed. You have better odds winning at a casino than getting a rebuilt PS pump that was rebuilt properly.
I had one pump start leaking on the alignment rack because the shaft wasn't touching the seal on one side sudden like. The shaft moved because the bearing let it move and all the bearing metal had to go somewhere. It ran for 30 min total since install. The oil was a glitter globe. I replaced everything, flushed the cooler, and put a filter on the return from the steering box. @ak diesel driver is correct: big job to replace the box, hydro-booster, and blasted PS pump again. I went through 5 PS pumps with one DOA like yours before I figured out the above way to obtain a working PS pump.
Pic on post 12 of bearing clearance you can see...