Quote Originally Posted by bee utey View Post
The VN pump certainly has a check valve. You can see the valve spring inside the pump outlet. It possibly got a sliver of rubber in it.

A reminder also that the fuel pressure regulator can be faulty. It is supposed to hold line pressure after shut down. If you can get a pressure gauge on the fuel rail you can clamp first the inlet hose then the outlet hose after shut down and see where the pressure is going.
I'll take your word for the check valve in the pump - I'm not taking it back out to check.

Although it's possible that the FPR could be faulty it seems a bit odd that the system was holding pressure with the old dying pump but now has the symptoms of holding zero pressure.