Fuel Pump

FUEL PUMP

OPERATION
- The fuel pump is driven when the engine is cranking and while the engine is running.
- When the engine is cranking and while the engine is running, the engine control module turns the power transistor ON to the fuel pump relay coil. This causes the fuel pump relay switch to turn ON, and current is supplied from the ignition switch via the fuel pump relay switch to drive the fuel pump.




INSPECTION
Using Scan Tool

HARNESS INSPECTION




Check the fuel pump.
- Apply battery voltage to the fuel pump relay II and operate the pump.
OK: GO TO STEP 4
NG: GO TO STEP 2




Check the ground circuit of the fuel pump.
- Fuel pump connector: Disconnected
OK: GO TO STEP 3
NG: Repair the harness. (B2 - Ground)




Check for an open-circuit, or a short-circuit to ground, between the fuel pump relay II and the fuel pump.
- Fuel pump relay II connector: Disconnected
- Fuel pump connector: Disconnected
OK: GO TO STEP 4
NG: Repair the harness. (B3 - C2)




Check for an open-circuit, or a short-circuit, to ground between the fuel pump relay II and the engine control module.
- Fuel pump relay connector: Disconnected
- Engine control module connector: Disconnected
OK: GO TO STEP 5
NG: Repair the harness. (C1 - 55)




Check for continuity between the fuel pump relay II and the resistor (for fuel pump).
- Fuel pump relay II connector: Disconnected
- Resistor (for fuel pump) connector: Disconnected
OK: GO TO STEP 6
NG: Repair the harness. (C4 - D1)




Check for continuity between the resistor (for fuel pump) and fuel pump.
- Resistor (for fuel pump) connector: Disconnected
- Fuel pump connector: Disconnected
OK: GO TO STEP 7
NG: Repair the harness. (B3 - D2)




Measure the power supply voltage of the MFI relay.
- MFI relay connector: Disconnected
- Voltage (V): 0-1 (Ignition switch: OFF )
Battery positive voltage (Ignition switch: ON)
OK: GO TO STEP 8
NG: Repair the harness. (Ignition switch [IG] - A3, A4)




Check for an open-circuit, or a short-circuit to ground, between the MFI relay and the engine control module.
- MFI relay connector: Disconnected
- Engine control module connector: Disconnected
OK: GO TO STEP 9
NG: Repair the harness. (A2 - 20)




Check for continuity between the MFI relay and the fuel pump relay II.
- MFI relay connector: Disconnected
- Fuel pump relay II connector: Disconnected
OK: STOP
NG: Repair the harness. (A1 - C3) (A1 - C5)

MULTIPORT FUEL INJECTION (MFI) RELAY AND FUEL PUMP RELAY CHECK
1. Remove the relay.







2. Check for continuity between the relay terminals.
3. Use the jumper leads to connect relay terminal 4 to the battery (+) terminal and terminal 2 to the battery (-) terminal.
4. Check the continuity between relay terminals 1 - 3 while connecting and disconnecting the jumper lead at the battery (-) terminal.







5. If there is a defect, replace the relay.

FUEL PUMP RELAY II CHECK




1. Remove fuel pump relay II.







2. Use a jumper wire to connect terminal (3) of fuel pump relay II and the positive terminal of the battery and use another jumper wire to connect terminal (1) and the negative terminal of the battery.
3. With the jumper wire connected to and disconnected from the negative terminal of the battery check the continuity between terminals (2) and (5) of fuel pump relay II and between terminals (4) and (5) of fuel pump relay II.
4. Replace fuel pump relay II if it is faulty.




FUEL PUMP CIRCUIT RESISTOR CHECK
1. Disconnect the connectors for the fuel pump circuit resistor.




2. Measure the resistance between the terminals

Standard value: 0.6 - 0.9 Ohm

3. If the resistance deviates from the standard value, replace the fuel pump circuit resistor.