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 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 and the fuel pump.
- Fuel pump relay connector: Disconnected
- Fuel pump connector: Disconnected
OK: GO TO STEP 4
NG: Repair the harness. (A1- B3)




Measure the power supply voltage of the fuel pump relay.
- Control relay connector: Disconnected
Voltage (V): 0-1 (Ignition switch: OFF )
Battery positive voltage (Ignition switch: ON)
OK: GO TO STEP 5
NG: Repair the harness. (Ignition switch - A3, A4) or check the ignition switch.




Check for an open-circuit, or a short-circuit, to ground between the fuel pump relay and the engine control module.
- Fuel pump relay connector: Disconnected
- Engine control module connector: Disconnected
OK: GO TO STEP 6
NG: Repair the harness. (A2-20)




Measure the power supply voltage of the fuel pump.
- Fuel pump relay connector: Connected
- Engine control unit connector: Connected
Voltage (V): 8 or higher (Engine cranking)
Battery positive voltage (Engine racing)
OK: STOP
NG: Fuel pump relay or engine control module is defective.

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.