GMT400 (1988–1998) Fuel Filter Replacement — OBS Maintenance Guide
Keeping your OBS truck running properly starts with clean fuel flow. A restricted or neglected fuel filter can cause hard starts, poor performance, hesitation, and premature fuel pump failure. This walkthrough covers the correct process for replacing the fuel filter on GMT400 Chevy and GMC trucks and SUVs.
Video guide:
Procedure Overview
1. Remove the fuel pump relay
Prevents pressure buildup before opening the fuel system.
2. Crank the engine
Relieves remaining fuel pressure and clears the lines.
3. Replace the fuel filter
Located under the driver-side frame rail.
• 13/16" wrench for the filter body
• 5/8" wrench for the fuel lines
4. Reinstall relay and start the truck
Check for leaks before driving.
Parts & Practical Tips
• OEM replacement: AC Delco GF652A (fits many GM trucks up to 2002)
• Use stainless steel filters — avoid plastic housings
• Apply penetrating oil if fittings are rusted or seized
• Crowfoot wrenches on an impact help in tight frame areas
• Service interval: every 3rd oil change (~15,000 km)
Real maintenance knowledge keeps these trucks alive.
Add your tips, tricks, or problems you’ve run into with stuck lines or failed filters below so future owners have a reference.