1. Prepare the car for work (see "Preparing the car for maintenance and repair").
2. Unscrew the protective cap of the diagnostic connector of the fuel rail.
3. Connect the pressure gauge hose tip to the fuel rail fitting. Using an open-end wrench by 14 mm we wrap the tip of the hose.
Tip: If necessary, the pressure in the fuel rail can be measured with a homemade device made from a pressure gauge from a foot pump. Before connecting such a pressure gauge, it is necessary to release the fuel pressure. After that, unscrew the valve from the fuel rail nipple. This can be done with a metal cap of a wheel valve. To connect the pressure gauge to the fuel rail nipple, use a piece of fuel-resistant hose of a suitable diameter. The ends of the hoses must be securely fastened with clamps.
4. Turn on the ignition. The fuel pump will work for a few seconds. Wait until the pump stops working, then turn off the ignition.
5. To remove air from the pressure gauge, lower the end of the drain tube into a small container, unscrew the pressure gauge bleed nipple by 1/3-1/2 turn, and release excess gasoline pressure from the fuel rail. This will remove air from the pressure gauge hose.
6. Tighten the bleed nipple until it stops.
We start the engine and measure the operating pressure in the fuel rail at different crankshaft speeds. In a serviceable engine it should be:
- for engine 2111 within 284-325 kPa (2.8-3.2 bar);
- for engine 11183 within 378-390 kPa (3.8-3.9 bar).
7. Turn off the ignition.
8. After lowering the end of the tube into the container, open the fitting and release the pressure from the fuel line.
9. Disconnect the pressure gauge from the diagnostic fitting of the fuel rail.
10. Screw the protective cap onto the fuel rail fitting.
Recommendation: If the working pressure in the fuel rail is not stable or higher than normal, then the fuel pressure regulator is faulty. Low pressure (below normal), can also be caused by a malfunction of the regulator. Perhaps the fuel pump mesh filter is clogged, or the fuel pump does not develop the required pressure. To clean the mesh filter, you need to remove the fuel module. You can verify the malfunction of the pressure regulator and fuel pump by replacing them with known good ones. You can also replace the fuel module as a whole.