Engine Controls - Basic Diagnostic Procedures - V6 & V8: Overview

Engine Controls - Basic Diagnostic Procedures - V6 & V8: Overview Toyota 4Runner III

FUEL PUMP OPERATION

Note. Electric fuel pump is located in the fuel tank. Electric fuel pump operation may be checked by using scan tool or by applying battery voltage to electric fuel pump with electric fuel pump installed in the fuel tank. Manufacturer also lists procedure to check fuel pump operation with fuel pump removed from fuel tank and fuel pump mounting bracket.

Scheme 31

Scheme 31: Checking Fuel Pump Operation Using Scan Tool (Avalon, Camry, Camry Solara, Sienna, Tacoma & 4Runner)

Scheme 32

Scheme 33

Scheme 34

Scheme 35

Scheme 36

Remove cover (if equipped) and connect scan tool to data link connector No. 3. (Scheme 31)- (Scheme 36). 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 fuel pump operating sound and feel for fuel pressure in fuel inlet line at fuel filter. Turn ignition off. Remove scan tool. If fuel pump operates, check fuel pressure. See «FUEL PRESSURE»(ref-91200-S30840421172001030500000).
If fuel pump does not operate, EFI main relay or circuit opening relay may be defective. For relay application and explanation of relay operation, see «FUEL PUMP CONTROL CIRCUIT»(ref-91200-S07056068062001030500000). For testing of EFI main relay or circuit opening relay, see MOTORS & RELAYS in SYSTEM & COMPONENT TESTING - V6 & V8 article.
If relays are okay, check for defective fuses, fusible links or wiring. See appropriate wiring diagram in WIRING DIAGRAMS article. If fuses, fusible links and wiring are okay, check for defective fuel pump. See appropriate «CHECKING FUEL PUMP OPERATION BY APPLYING BATTERY VOLTAGE TO FUEL PUMP»(ref-91200-S15892936712001030500000). If fuel pump operates properly, Engine Control Module (ECM) may be defective.

Checking Fuel Pump Operation Using Scan Tool (Land Cruiser)

Connect scan tool to data link connector No. 3. (Scheme 37) 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. Remove intake manifold cover located on top of engine, above intake manifold. Intake manifold cover must be removed for access to fuel pressure pulsation damper located at firewall end of driver's side fuel rail. (Scheme 38) Fuel pressure pulsation damper may also be referred to as pulsation damper.
Listen for operating sound at in-tank fuel pump and check that screw at center of fuel pressure pulsation damper moves upward due to the fuel pressure. (Scheme 38) If fuel pump operates, check fuel pressure. See «FUEL PRESSURE»(ref-91200-S30840421172001030500000).
If fuel pump does not operate, EFI main relay, fuel pump Electronic Control Unit (ECU) or fuel pump switch may be defective, or fuel pump switch may need to be reset. For explanation of EFI main relay, fuel pump ECU and fuel pump switch operation, or resetting of fuel pump switch, see «FUEL PUMP CONTROL CIRCUIT»(ref-91200-S07056068062001030500000). For testing of EFI main relay, see MOTORS & RELAYS in SYSTEM & COMPONENT TESTING - V6 & V8 article. For testing of fuel pump switch, see FUEL SYSTEM in SYSTEM & COMPONENT TESTING - V6 & V8 article.
If EFI main relay and fuel pump switch are okay, check for defective fuses or wiring. See appropriate wiring diagram in WIRING DIAGRAMS article. If fuses and wiring are okay, check for defective fuel pump. See appropriate «CHECKING FUEL PUMP OPERATION BY APPLYING BATTERY VOLTAGE TO FUEL PUMP»(ref-91200-S15892936712001030500000). If problem exists in fuel pump ECU or control circuit, Diagnostic Trouble Code (DTC) P1200 may be stored in Engine Control Module (ECM). See SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - INTRODUCTION article for retrieving of DTCs.

Scheme 37

Scheme 38

Checking Fuel Pump Operation By Applying Battery Voltage To Fuel Pump (Avalon, Camry, Camry Solara, Land Cruiser, Sienna, Tacoma & 4Runner)

On Avalon, Camry and Camry Solara, remove rear seat and cover plate on floor panel for access to electrical connector for fuel pump.
On Land Cruiser, remove second seats, rear door scuff plates, step plates, second seat lock covers, rear carpet and cover plate on floor panel for access to electrical connector for fuel pump.
On Sienna, manufacturer recommends removing fuel tank for access to fuel pump.
On Tacoma and 4Runner, it may be necessary to lower fuel tank for access to electrical connector for fuel pump.
On all models, disconnect electrical connector for fuel pump. This is electrical connector for fuel pump and fuel gauge sending unit and is located on top of fuel tank, near fuel pump.
Connect battery voltage to specified terminals on fuel pump to activate fuel pump. (Scheme 39)- (Scheme 43). DO NOT apply battery voltage to fuel pump for more than 10 seconds.
Listen for fuel pump operating sound. Disconnect battery voltage from fuel pump. If fuel pump operates, check fuel pressure after reinstalling components. See «FUEL PRESSURE»(ref-91200-S30840421172001030500000).
If fuel pump fails to operate, replace fuel pump and/or lead wire to fuel pump (if equipped). See FUEL SYSTEM in REMOVAL, OVERHAUL & INSTALLATION - V6 & V8 article. If fuel pump will not operate while trying to start engine, see appropriate CHECKING FUEL PUMP OPERATION USING SCAN TOOL under «FUEL PUMP OPERATION»(ref-91200-S10043743052001030500000) for additional testing information.