Engine Controls - Basic Testing: Overview

Engine Controls - Basic Testing: Overview Lexus LX J80

FUEL PUMP OPERATION

Note. Electric fuel pump operation may be checked by using scan tester or by applying battery voltage to fuel pump.

Remove cover (if equipped) and install scan tester on data link connector No. 3. (Scheme 1) Turn ignition on. DO NOT start engine.
Using scan tester manufacturer's instructions, activate fuel pump. Listen for fuel pump operating sound and feel for pressure in fuel inlet line near fuel filter. Turn ignition off. Remove scan tester. If fuel pump operates, check fuel pressure. See «FUEL PRESSURE».
If fuel pump does not operate, EFI main relay, circuit opening relay or fuel pump relay (if used) may be defective. For relay application and explanation of relay operation, see «FUEL PUMP CONTROL CIRCUIT».
If relays are okay, check wiring circuit and fuses. If fuel pump does not operate, check for defective fuel pump or defective fuel pump ground circuit. See appropriate wiring diagram in WIRING DIAGRAMS article.

Remove second seat, scuff plate, step plate, floor mats and cover plate on floor panel for access to electrical connector at fuel pump.
Disconnect electrical connector for fuel pump. NOTE: Electrical connector for fuel pump is located near fuel pump. CAUTION: When applying battery voltage to fuel pump, DO NOT apply battery voltage for more than 10 seconds, or fuel pump may be damaged.
Connect battery voltage to specified terminals on fuel pump to activate fuel pump. (Scheme 2) DO NOT apply battery voltage to fuel pump for more than 10 seconds.
Listen for fuel pump operating sound and feel for pressure in fuel line near fuel filter. If fuel pump operates, check fuel pressure. See «FUEL PRESSURE». Disconnect battery voltage from fuel pump.
If fuel pump fails to operate, replace fuel pump. If fuel pump will not operate while trying to start engine, EFI main relay, circuit opening relay or fuel pump relay (if used) may be defective. For explanation of relay operation, see «FUEL PUMP CONTROL CIRCUIT».
If relays are okay, check wiring circuit, fuses and fuel pump ground. See appropriate wiring diagram in WIRING DIAGRAMS article. Reinstall electrical connector and remaining components.