[Schulisco]

Originally Posted by leonardo911sc

What i dont understand is that when i disconnect the WUR to FD line after 1 day there will be not even a single drop of fuel although residual pressure is within spec.

That's weird! Never seen before. I always had fuel there. Of course more with reisdual pressure and less. if the RP is already gone. That's would explain why it took that much time to get a control pressure being measured...!
Did you checked the fuel lines being correct connected? The middle output/input of the FD supplies the WUR. And the WUR is being connected to the fuel return lines. I don't expect that it qould make a difference if the WUR is in wrong direction, but who knows? Of the FD has a problem that it won't supply the WUR with enough fuel...

Here's a good fuel flow diagram: https://jimsbasementworkshop.com/CIS/pages/fuel_flow.html

Remember: I have a new original Bosch fuel pump with a new check valve mounted. The check valve is far more important than most people expect...it works very closely together with the fuel pressure accumulator.

Thomas