Hey sorry D&D I did not realize you would take offense to that. I am sure if you disconnect the hose going to the cylinder and put a pressure gauge on it and operate the valve you would have a pressure reading that could be useful. I guess my point is you could pin prick a garden hose and get tons of pressure but not enough gpm to wash your truck.
Don't worry about it, you can be on the list I'm on.....
I agree. Although, a pressure test on either of the quick couplers would let us know if the pump even has the ability to build pressure.
The amount of flow required to lift the bed is totally dependent on how much speed you want.
When the valve is in the neutral position the pump is creating no pressure. All it's doing is flowing. Pressure is only created when the pump pushes against a closed circuit. If you move the bed lever to the "raise" position and the cylinder extends to it's limit and you continue to hold the lever you will hear the PRV open.
So I agree with your analysis. We haven't completely ruled out pump problems yet. But we are getting closer.
I believe if the valve is disassembled you'll find the valve plunger has no O-rings. It's a simple metal assembly that slides thru the metal hole in the valve body. In this process it directs the pump flow to various ports.
I guess I'd try disassembling the valve and checking the PRV. It might have completely failed and is allowing the fluid to simply return to tank without creating any pressure??
I certainly wouldn't buy an $800 valve without investigating farther. Maybe remove the valve and disassemble it as far as you feel comfortable doing and take it to a hydraulic expert that you trust to look it over??
Going back to the pump, I've experienced a pump destroyed by pushing against a PRV and overheating. As I said earlier, when disassembled all I saw was scoring in the pump case at the ends of the gears. Looked fine. Wouldn't create any pressure.
I'm very interested to see the outcome of this problem.
This is also a very good thread that hopefully reaches a conclusion. It will be valued in the archives of this forum.