1. Depressurize the fuel supply system as described above for removing the central injection unit.
2. Connect the electrical wires to the electric fuel pump. Disconnect the fuel line from the inlet fitting of the central injection unit and connect a pressure gauge through the tee between the fitting and the fuel line.
3. Put the ignition key in position "Ignition", check the tightness of the pressure gauge connection and its readings. The pressure should be within 190...210 kPa. If there is no pressure, check by ear whether the electric fuel pump turns on when the ignition key is turned to the position "Ignition" (the operation of the pump and the clicks of the operation of its relay can be heard while in the passenger compartment).
4. If the electric fuel pump does not turn on, it is necessary to check the electrical circuits of the pump.
5. After two seconds of operation, the electric fuel pump should turn off, since when the engine is not running, reference signals for the position of the crankshaft do not enter the electronic control unit. To turn on the pump again, you must turn off the ignition for ten seconds and turn it on again.
6. After stopping the electric fuel pump, the pressure may decrease slightly and stabilize, or vice versa - increase if the engine is warmed up. If the pressure does not stabilize and decreases, turn on the electric fuel pump and immediately after it stops, pinch the fuel supply hose to the central injection unit.
7. If at the same time the pressure does not drop, then check the tightness of the fuel lines from the tank to the central injection unit, as well as the fuel fine filter, then repeat the pressure test in the fuel supply system.
8. Low pressure (below 190 kPa) may be caused by a malfunctioning fuel pressure regulator or a limited capacity of the fuel delivery system.
9. The throughput of the fuel supply system can be determined from the fuel consumption for draining. If necessary, replace the fuel fine filter with a new one.
10. The operation of the pressure regulator can be checked by reading the pressure gauge, for which disconnect the drain hose and lower it into the prepared container. Turn on the electric fuel pump, pinch the drain hose and check the pressure on the pressure gauge that the pump can create. Release the hose. The gauge will show the set pressure of the regulator valve. Replace pressure regulator if necessary.
11. Increased pressure in the fuel supply system (over 210 kPa) may be caused by a malfunctioning fuel pressure regulator or increased resistance to fuel draining into the tank. To check, connect a pressure gauge to the fuel supply system, disconnect the drain hose in the engine compartment and lower it into a container. Turn on the electric fuel pump and check the pressure in the system according to the pressure gauge.
12. If the pressure is too high, replace the fuel pressure regulator. If this does not help, then find and eliminate the cause of increased resistance to fuel drain.