Execution sequence
1. We prepare the car for work («Preparing the car for maintenance and repair»).
2. Turn off the protective cap of the diagnostic fitting of the fuel rail.
3. We connect the tip of the pressure gauge hose to the diagnostic fitting of the fuel rail.
Advice. If necessary, the pressure in the fuel rail can be measured with a home-made device, made from a pressure gauge from a foot pump. Before connecting such a pressure gauge, the fuel pressure must be relieved. After that, unscrew the spool from the fuel rail fitting. This can be done with a metal cap from the wheel nipple. To connect the pressure gauge to the fuel rail fitting, use a piece of gasoline-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 then operate for a few seconds. After waiting for the pump to stop working, turn off the ignition.
5. To remove air from the pressure gauge, lowering the end of the drain tube into a small container, unscrew the bleed valve of the pressure gauge by 1 / 3-1 / 2 turns and relieve the excess pressure of gasoline from the fuel rail. This will remove air from the pressure gauge hose.
6. We wrap the bleeder fitting until it stops. We start the engine and measure the working pressure in the fuel rail at different crankshaft speeds. For a serviceable engine, it should be in the range of 378-390 kPa (3.8-3.9 bar).
7. Turn off the ignition.
8. Having lowered the end of the tube into the container, open the fitting and relieve 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 operating pressure in the fuel rail is unstable or higher than normal, then the fuel pressure regulator is faulty. Low pressure (less than normal) can also be caused by a faulty regulator. the fuel pump strainer may be clogged, or the fuel pump may not be developing the required pressure. To clean the strainer, you need to remove the fuel module. You can verify that the pressure regulator and fuel pump are faulty by replacing them with known good ones. You can also replace the fuel module assembly.