Preliminary check
1. If the fuel supply is insufficient, then do the following.
2. Check the fuel level in the tank and the fuel filter, replace the filter if necessary.
3. With the engine running, check that there are no fuel leaks in the fuel lines. Tighten loose connections, Check condition of all hoses.
Pressure test
4. Decompress the fuel system.
5. On TBI models, disconnect the fuel pressure hose from the inlet on the TBI module, install a tee with a fuel gauge in place of the hose. On SFI models, screw a fuel gauge into the fuel pressure port.
6. Turn off the ignition, connect the positive pole of the battery with a wire to the diagnostic output of the fuel pump. On pre-1995 models, this pin is located in the assembly line data link (technological connector) (see photo). On models since 1996, the fuel pump diagnostic connector is located under the hood near the fusible links.
7. Read the pressure reading. If the pressure is normal, no further check is necessary.
8. If the fuel pressure is higher than normal, then check the cleanliness of the fuel line. If no blockage is found in the line, replace the fuel pressure regulator.
9. If the pressure is less than normal, then slowly pinch the fuel return hose, watching the pressure. If the pressure rises above normal, replace the pressure regulator.
10. If the pressure is still below the specified value, then check the cleanliness of the fuel line, including the fuel filter and pump filter. If there is no blockage, then replace the fuel pump.
11. At the end of the test, decompress and remove the pressure gauge.
Fuel pump check
12. When the ignition is switched on, a characteristic sound from the pump should be heard from the side of the tank.
13. If the pump does not work, then check the pump fuse located in the engine compartment (see photo). Replace blown fuse.
15. Turn off the ignition and apply 12 V to the diagnostic output of the fuel pump (see photo above).
16. If the pump is running, check the pump relay. Otherwise, check the circuit between the relay and the pump.
Checking the fuel pump relay
17. Warm up the engine and at idle, disconnect the fuel pump relay (see photo). If the engine stalls, then the oil pressure sensor is faulty.
18. If the engine continues to run, then put the relay in place and turn off the ignition, connect a test lamp to the diagnostic output of the pump. If the lamp is lit, then the circuit is working, if not, then the oil pressure sensor is faulty.