Author Topic: HOW TO: Set your System and WUR fuel pressure (Stealth Mod)  (Read 10543 times)

Offline Deefadog

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  • Mk2 16V (November 89)
OK, to set your fuel pressure correctly, you will need a fuel pressure gauge with stop taps on it and a 6 mm metal drill bit and drill. - good plce for the gauge is here - http://www.fuelsystem.co.uk/guages.htm

NOTE - This is not as accurate as having it set up by stealth or other professionals as you really need a rolling road to test it against as some cars may need slightly different pressures to find there best, but this is pretty accurate.

Also this the first draft, i will be adding more pics and info when i get them :)

Preparing the WUR

1) - First - disconnect the fuel unions going to the WUR (Warm Up Regulator), put an old towel below the WUR and use a small jug to catch any fuel, about a table spoon comes out!

2) - Then undo the WUR by the two allen key bolts, and remove!

3) - Then shake any excess fuel out of the WUR and leave upside down - fuel inlet and outlets down side on to a cloth to make sure all fuel is out, you can leave this for about half an hour to be sure.

4) - Then put the WUR on to a work bench and secure it, making sure the brass cap (back of the WUR) is facing upward. Then using your 6mm drill bit slowly drill into the centre of the brass cap, do this very slowly as it's not that thick, ideal you do not want to hit the hidden allen key on the other side.

5) - You should now see the allen key screw, make sure you can easily fit an allen key into it, but don't turn it yet! you can mark it with some tipex on the screw and the side of the WUR, as if it all goes wrong you know where it was to begin with.



6) - Re-attach the fuel lines to the WUR, but leave the WUR securing bolts off for now!

Fuel pressure gauge

1) - Connect the fuel pressure gauge up between the metering head supply to the WUR and the WUR line. Make sure all the connection are tight! and the shutoff valves are open.











2) - Now start the car (may take a few turns to get the fuel flowing again) and the pressure should start to rise on the gauge.

3) - Watch the the gauge rise, if your WUR is working it should steadily rise smoothly, no jumps! after about a minute/minute 20 secs it should stop rising - note the pressure.

4) - Now to see the system pressure - turn off the shut off valve closest to the WUR side.  The pressure should rise further, once it has stop and the car is at full temp, this is your system pressure.

5) - Also check the fuel pump is getting the correct healthy supply of battery voltage! this can effect the system pressure!

Ideal system pressure is around 5 bar!

6) - If it is higher or lower you can adjust this by taking the shims out of the valve (see B below), I never needed to adjust mine, and i found it was impossible to get hold of different thickness shims, a scrap-yard would be your best bet.

A 0.5mm shim (depending on the spring condition) should give you .75 bar pressure increase.

A 0.1mm shim should give you about 0.15bar increase.

7) - Now turn off the engine and keep an eye on the gauge, the pressure should not drop below 2 bar after 20 minutes, this indicates that your fuel accumulator is doing it's job and holding pressure.

8) - Once you have set the correct system pressure, re-open the shut off valve on the gauge, and the pressure will drop to give you the control pressure from the WUR, you are ideally looking for 3.4 bar (48psi).

9) - Now set the pressure by turning the allen key screw on the back of the WUR until you reach 3.4 bar.

10) - Now turn engine off and remove the gauge and tighten up all the connections. 

11) - Then re-attach the WUR to the engine.

12) - As the control pressure has been changed, you now need to set the C0 (mixture) as this will be affected, follow the guide on here  - http://www.golfgtiforum.co.uk/index.php?topic=22031.0 or take it to an MOT testing station, chuck em a fiver and ask to put it on there gas machine and set it to 2% (red lead disconnected and breather pipe, air-box end removed and air-box blocked).


Job done :)

Thanks to a lot of people for the information i used here, i can't take all the credit for it, but at least it's all in one place now :)

 :santa:






« Last Edit: 11 September 2006, 14:49 by Mk2GTI2.016v »
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