Mine leaks down to near zero pressure, but holds just enough(maybe 1/2psi) to keep fuel in the lines. How long should a healthy check valve hold fuel pressure? A week, a month; I don't know.[/QUOTE]
From the Manual
7. Pressure should not fall below 2.5 bar (36 psi) after 30 minutes.
8. If pressure falls below 2.5 bar (36 psi) within 30 minutes, it must be determined if a fuel injector, the check valve within the fuel pump, or a fuel tube/line is leaking.[/QUOTE]

Dave, I think you missed my point. I did the tests from the manual, so I know about items #7 & 8. The point is that it shouldn't fall below 36 after 30 minutes, but it does, and still operates fine. Manual doesn't say whether it can fall to zero after 1 hr? 1 day? Is it supposed to hold pressure indefinitely? I doubt it.