Fuel pump control circuit Description: When the ignition switch is turned on, the engine control module to the fuel pump relay to provide 12V supply voltage, the fuel pump to work. If the pump does not receive an ignition reference pulse from the ECM, the engine control module will shut off the power to the fuel pump relay and the fuel pump will stop working.
Fuel pump control circuit check the following steps:
1, confirm the fuel pump circuit is faulty
â‘ ignition switch to turn off 10s.
â‘¡ Ignition switch to turn on, but the engine does not run.
â‘¢ listen to the action of the fuel pump.
Fuel pump should be able to work 2s, if you can hear the fuel pump work 2s, said the fuel pump control circuit is normal. If you can not hear the fuel pump work, you should proceed to the next inspection.
2, check the fuel pump relay terminal 30 (harness side) to 30 lines between the circuit is faulty
â‘ Turn off the ignition switch.
â‘¡ disassemble the fuel pump relay.
â‘¢ Connect the other end of the well-grounded test lamp to the fuel pump relay terminal 30 (harness side).
If the test light does not turn on, repair the circuit. If the test light turns on normally, the next step should be checked.
3, check the fuel pump relay terminal 85 and ECM terminal K54 circuit is faulty
â‘ Turn off the ignition switch.
â‘¡ disconnect the fuel pump relay.
â‘¢ Connect the other end of the well-grounded test lamp to the fuel pump relay 85 (harness side)
If the test light does not turn on, disconnect the ECM harness and check if the circuit between the fuel pump relay terminal 85 and the ECM terminal K54 is open. If the circuit is open, repair the circuit. If there is no open circuit, replace the ECM. If the test light to normal light 2, the next step should be checked.
4, check the fuel pump relay 86 and ground circuit is faulty
â‘ disassemble the fuel pump relay.
â‘¡ Connect the other end of the test lamp that is connected to the positive terminal of the battery to the fuel pump relay terminal 86 (harness side).
If the test light does not turn on, repair the circuit. If the test light turns on normally, the next step should be checked.
5, check the fuel pump relay is faulty
â‘ Replace the fuel pump relay.
â‘¡ One end of a good test light grounded fuse Efi8.
â‘¢ Connect the ECM harness.
Turn the ignition switch to ON.
If the test light does not light, should check the fuel pump and fuse Efi8 circuit. If necessary, carry out repairs. Fuel pump relay and fuse Efi8 between the circuit if normal, you should replace the fuel pump relay.
If the test light turns on normally for 2s, the next step should be checked.
6 Check if the fuel pump is defective
â‘ Disconnect the fuel pump harness.
â‘¡ Span the test lamp between fuel pumps 2 and 3 (harness side).
Turn the ignition switch to ON.
If the test light does not turn on, maintain the ground connection of the fuel pump or the Efi8 circuit between the fuel pump and the fuses. If the test light can be turned on normally 2s, should replace the fuel pump.