[ZV8888]

Are these WUR re-calibration steps correct?

WUR model - Bosch 069 (with vacuum)

Current pressures:
System pressure 5 bar
Cold 3.3 bar @ 15C
Warm with vacuum 4.2 bar
Warm without vacuum 2.2 bar

According to Bentley they should be:
System pressure 5 bar (Something is right!)
Cold 1.7 bar @ 15C
Warm with vacuum 3.4 bar
Warm without vacuum 2.9 bar

My understanding of the issues:
The cold pressure is too high so I need to raise the post that holds the bi-metallic strip / arm
The warm control pressure with vacuum it too high so I need to lower the brass cap that holds the diaphragm in place
The warm control pressure without vacuum is too low so I need to raise the piston in the middle of the diaphragm

On to the plan - with the engine cold ....
(0) Connect fuel pressure tester by replacing the pipe from the fuel distributor to the WUR with the pressure tester ensuring the tap side is connected to the WUR
(1) Tap out the brass cap until nearly flush with case
(2) Tap out the post holding the bi-metallic arm so it is nearly flush with the case
(3) Loosen nut on the bi-metallic arm
(4) Using an allen key, raise the position of the piston in the middle of the diaphragm by turning clockwise .... maybe 2 revolutions (Any comments/advice)?
(5) Re-assemble and install without connecting the vacuum tubes or heater wiring
(6) Run the fuel pump only by shorting the relay (pin 30 to 87A)
(7) Open the valve on the pressure test gauge so that it reads 3.6 bar (Why 3.6 bar? ... Yesterday I did a job on this WUR and I set it to 2.9 bar, but found that it ended up at 2.2 bar when running without vacuum, so when running, it seems to make a difference of (2.9 - 2.2 = 0.7) bar. I'm not convinced I am right with this because the scale may not be linear and I have adjusted the piston in the diaphragm in step (4) - Any comments/advice?)
(8) Tap the brass cap in until I see a pressure increase on my gauge, then open the gauge valve a bit more to reset it back to 2.9 bar.
(9) Repeat (8) until the gauge valve is fully open
(10) Remove WUR, open and then tighten up the bi-metallic arm
(11) Re-assemble and install without connecting the vacuum tubes or heater wiring
(12) Open the valve on the pressure test gauge
(13) Tap in the post holding the bi-metallic arm until the gauge reads 1.7 bar (I did this yesterday too and I can't understand why the cold pressure is so far out of spec ....)
(14) Connect vacuum tubes and heater wiring
(15) Replace fuel relay
(16) Start engine and check cold control pressure is correct
(17) Watch the pressure raise from cold control to warm control pressure with vacuum and check if correct value
(18) Remove the bottom vacuum hose and check if warm control pressure without vacuum is correct

The variable here is step (4). If my guess is off the mark then I will have to repeat most of the steps above with the exception of the cold pressure steps. Some people talk about drilling a hole in the brass cap so that you can adjust the piston in the middle of the diaphragm without dismantling but I reckon this would mess up your vacuum side so I have no intention of doing this. Maybe you can use this trick on WUR's that don't have a vacuum control.

One thing that occurs to me, since I tried to set up the WUR yesterday using much of the above steps .....
(a) Is it coincidental that my cold control = system pressure - the value I set using the above method yesterday ( 3.3 = 5.0 - 1.7) or am I doing something wrong?
(b) Is it coincidental that my warm control without vacuum (nearly) = system pressure - the value I set using the above method yesterday ( 2.2 = 5.0 - 2.9) or am I doing something wrong?

And yes, I have read many of the CIS posts in the forum, but that doesn't mean that I understood them correctly. The above is the my understanding of the issues and my understanding of the solution (others be warned). I appreciate the confirmation / comments / advice on the above steps and maybe it will help others too.