Contents: Preliminary check ↧ Pressure check ↧ Checking the fuel pump ↧ Checking the fuel pump relay ↧
Preliminary check
1. If the fuel supply is insufficient, 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 for fuel leaks in the fuel lines. Tighten any loose connections. Check the condition of all hoses.
Pressure check
4. Decompress the fuel system.
5. On TBI models, disconnect the fuel pressure hose from the inlet on the TBI module and install a tee with a fuel pressure gauge in its place. On SFI models, screw a fuel pressure gauge into the fuel pressure port.
6. Turn the ignition off, connect a wire from the positive battery terminal to the fuel pump diagnostic lead. On pre-1995 models, this lead is located in the assembly line data link (technological connector) (see photo). On 1996 and later models, the fuel pump diagnostic connector is located under the hood near the fusible links.
7. Read the pressure reading. If the pressure is normal, there is no need for further checking.
8. If the fuel pressure is higher than normal, 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, slowly pinch the fuel return hose, monitoring the pressure. If the pressure rises above normal, replace the pressure regulator.
10. If the pressure is still below the specified value, check the cleanliness of the fuel line, including the fuel filter and pump filter. If there is no blockage, replace the fuel pump.
11. After completing the check, decompress and remove the pressure gauge.
Checking the fuel pump
12. When the ignition is turned on, a characteristic sound from the pump should be heard from the tank side.
13. If the pump does not work, check the pump fuse located in the engine compartment (see photo). Replace the blown fuse.
15. Turn off the ignition and apply 12 V to the fuel pump diagnostic output (see photo above).
16. If the pump works, 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 speed disconnect the fuel pump relay (see photo). If the engine stalls, the oil pressure sensor is faulty.
18. If the engine continues to run, then put the relay back in place and turn off the ignition, connect the test lamp to the diagnostic output of the pump. If the lamp lights up, then the circuit is OK, if not, then the oil pressure sensor is faulty.