Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Checking Fuel Pump Operation (Using Lexus Scan Tool)
1998 Lexus GS 300SECTION Checking Fuel Pump Operation (Using Lexus Scan Tool)
- Connect Lexus scan tool to Data Link Connector (DLC) No. 3. See Fig 1. Turn ignition on. Turn scan tool on. DO NOT start engine.
- Select ACTIVE TEST mode on scan tool. Using Lexus scan tool manufacturer's instructions, activate electric fuel pump. On all models except GS300 and SC300, fuel pump is operating if fuel pump operating sound can be heard or pulsations can be felt in fuel line near fuel filter. On GS300 and SC300, check that fuel pressure pulsation damper screw rises when fuel pump operates. See Fig 2.
- If fuel pump operates, check fuel pressure. See FUEL PRESSURE . If fuel pump does not operate, check for a defective EFI main relay, fuel pump, fusible link, ECM or poor wiring connections. Check for a defective AM2 (30-amp) fuse located in engine compartment fuel relay box, left side of engine compartment. Check for a defective IGN (5-amp) fuse located in instrument panel fuel/relay box, at bottom left of steering column.
- If all components are okay and fuel pump still does not operate, check for defective fuel pump or fuel pump ground. See appropriate wiring diagram in WIRING DIAGRAMS article.
RENDER: 1.0x
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.