Checking Fuel Pump Operation Using Scan Tool (Non-Turbo)
- Connect scan tool to data link connector No. 3. See Fig 1. Turn ignition on. DO NOT start engine.
- Turn scan tool on. Select ACTIVE TEST MODE on scan tool. Using scan tool manufacturer's instructions, activate fuel pump.
- Listen for operating sound at fuel pump and check that screw at center of fuel pressure pulsation damper moves upward due to the fuel pressure. See Fig 2. Fuel pressure pulsation damper is located at driver's side rear corner of fuel rail, near valve cover.
- Turn ignition off. Remove scan tool. If fuel pump operates, check fuel pressure. See FUEL PRESSURE (FUEL SYSTEM) . If fuel pump does not operate, go to next step.NOTE: If fuel pump operates with scan tool, but will not operate otherwise, go to step 11).
- Remove carpet and necessary panels for access to fuel pump Electronic Control Unit (ECU). See Fig 3. Disconnect Black 5-pin connector at fuel pump ECU.
- Turn ignition on. Using voltmeter, check voltage between ground and terminal No. 4 (Black/Red wire) at fuel pump ECU wiring harness connector. Voltage should be 9-14 volts.
- If voltage is within specification, go to next step. If voltage is not within specification, check for open or short in wiring harness between EFI main relay and fuel pump ECU. See appropriate wiring diagram in WIRING DIAGRAMS article. EFI main relay is located in fuse/relay box at driver's side front corner of engine compartment, near the battery. For explanation of EFI main relay operation, see FUEL PUMP CONTROL CIRCUIT under FUEL SYSTEM. Repair wiring as necessary. If necessary to check EFI main relay, see SYSTEM/COMPONENT TESTS article.
- Using voltmeter, check voltage between terminals No. 1 (White/Black wire) and No. 3 (Violet/White wire) on fuel pump ECU wiring harness connector. Voltage should be 4.5-5.5 volts. If voltage is within specification, go to next step. If voltage is not within specification, go to step 10).
- Check for defective fuel pump. See CHECKING FUEL PUMP OPERATION BY APPLYING BATTERY VOLTAGE TO FUEL PUMP under FUEL SYSTEM. Replace fuel pump if defective. If fuel pump is okay, check for open or short in wiring harness between terminal No. 5 (Blue/Red wire) at fuel pump ECU, fuel pump (Blue wire) and ground (White/Black wire). See appropriate wiring diagram in WIRING DIAGRAMS article. Repair wiring as necessary. If wiring is okay, replace fuel pump ECU. See REMOVE/INSTALL/OVERHAUL article.
- Check for open or short in Violet/White wire between terminal No. 3 at fuel pump ECU and Engine Control Module (ECM). ECM is located below passenger's side of instrument panel, underneath the carpet on the floor, below glove box. Also check for open in White/Black wire between terminal No. 1 at fuel pump ECU and ground. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair wiring if necessary. If wiring is okay, replace ECM. See REMOVE/INSTALL/OVERHAUL article.
- Remove carpet and necessary panel for access to Fuel Pump Electronic Control Unit (ECU). See Fig 3. Disconnect Black 5-pin connector at fuel pump ECU.
- Check for open or short in Green wire between terminal No. 2 at fuel pump ECU and Engine Control Module (ECM). ECM is located below passenger's side of instrument panel, underneath the carpet on the floor, below glove box. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair wiring if necessary. If wiring is okay, replace ECM. See REMOVE/INSTALL/OVERHAUL article.