Attention! The "DIS" system pressure indicator shows the absolute pressure value taking into account the ambient pressure.
The filler cap overpressure valve should be checked in the following order.
Prepare the equipment "13.3.010", "16.1.171", "16.1.172" and "16.1.173" and install the pressure regulator on the device "16.1.171" (fig. 6.101) until it stops in the "–" position.
Connect the "16.1.171" device using the hose (1) to a source of compressed air 8–10 bar (8–10 kgf/cm²). Connect the pressure gauge sensor (2) of the "DIS" system with a measuring range of 0–3.5 bar (0–3.5 kgf/cm²).
Select one of the devices, "16.1.172" or "16.1.173", that fits the vehicle's filler cap, and install the device "16.1.171" on the quick-release coupling.
Install the filler cap on the selected device. Check the leak tester, for which:
- select the "Measurement System" mode on the "DIS" system;
- set the measurement range according to the pressure sensor to 0–3.5 bar;
- using the pressure regulator on the device "16.1.171" increase the pressure by 0.2 bar;
- using the device "13.3.010" pinch the pipeline from the device "16.1.171" to the filler neck of the fuel tank;
- wait 60 sec;
- read the pressure value and compare it with the initial value.
Conduct an evaluation of the obtained measurements:
- if the pressure drop exceeds 0.012 bar, it means that the testing device is not sealed;
- check the tightness of the connections.
Check the filler cap overpressure valve, for which:
- select the "Measurement System" mode on the "DIS" system;
- set the measurement range according to the pressure sensor to 0–3.5 bar;
- using the pressure regulator on the device "16.1.171" increase the pressure by 0.3 bar;
- using the device "13.3.010" clamp the pipeline from the device "16.1.171" to the filler neck of the fuel tank.
- wait 60 sec;
- read the pressure value and compare it with the initial value.
Conduct an evaluation of the obtained measurements:
- if the pressure drop exceeds 0.012 bar, it means that the overpressure valve of the filler cap is faulty;
- replace the filler cap.
[The original text is available on the website «BMWMAN.ru»]