1. Relieve the pressure in 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 supply nipple of the central injection unit and connect a pressure gauge through a tee between the nipple and the fuel line.
3. Turn the ignition key to the "Ignition" position, 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 "Ignition" position (the operation of the pump and the clicks of its relay can be heard while inside the car).
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 switch off, since when the engine is not running, the electronic control unit does not receive reference signals from the crankshaft position. To switch the pump on again, you must switch off the ignition for ten seconds and switch it on again.
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6. After the electric fuel pump stops, the pressure may decrease slightly and stabilize, or, on the contrary, increase if the engine is warm. 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 the pressure does not drop, check the tightness of the fuel lines from the tank to the central injection unit, as well as the fine fuel filter, then repeat the pressure check in the fuel supply system.
8. Low blood pressure (below 190 kPa) may be caused by a faulty fuel pressure regulator or a restriction in the fuel supply system.
9. The fuel consumption for draining can be used to determine the capacity of the fuel supply system. If necessary, replace the fine fuel filter with a new one.
10. The operation of the pressure regulator can be checked using the pressure gauge readings. To do this, 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 that the pump can create using the pressure gauge. Release the hose. The pressure gauge will show the pressure at which the regulator valve operates. Replace the pressure regulator if necessary.
11. Increased pressure in the fuel supply system (over 210 kPa) may be caused by a faulty 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 using the pressure gauge readings.
12. If the pressure is higher than normal, replace the fuel pressure regulator. If this does not help, then find and eliminate the cause of increased resistance to fuel drain.