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Home >> Mitsubishi >> 2000 >> Montero 4WD V6-3.5L SOHC >> Repair and Diagnosis >> Powertrain Management >> Computers and Control Systems >> Testing and Inspection >> Component Tests and General Diagnostics >> Fuel Pump
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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 supply power 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.

Using Scan Tool:




INSPECTION

HARNESS INSPECTION




STEP 1. Check the fuel pump.
- Apply battery positive voltage to the fuel pump relay and operate the pump.
OK: GO TO STEP 4
NG: GO TO STEP 2




STEP 2. Check the ground circuit of the fuel pump.
- Fuel pump connector: Disconnected
OK: GO TO STEP 3
NG: Repair the harness. (B1 - Ground)




STEP 3. Check for an open-circuit, or a short-circuit to ground, between the fuel pump relay and the fuel pump.
- Fuel pump connector: Disconnected
- Fuel pump relay connector: Disconnected
OK: GO TO STEP 4
NG: Repair the harness. (A1 - B2)




STEP 4. Measure the power supply voltage of the fuel pump relay.
- Fuel pump relay connector: Disconnected
Voltage (V):
0 (ignition switch: OFF)
Battery positive voltage (ignition switch: ON)
OK: GO TO STEP 5
NG: Repair the harness. (A3 - Ignition switch-IG, A4 - Ignition switch-IG) or check the ignition switch.




STEP 5. Check for an open circuit or a short-circuit to ground between the MFI 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)




STEP 6. Measure the power supply voltage of the fuel pump.
- Fuel pump relay connector: Connected
- Engine control module 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.







FUEL PUMP RELAY CHECK
1. Check for continuity between the fuel pump relay terminals.
2. If there is a problem replace the fuel pump relay.

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