LS Swap Fuel System Guide for 1988–1998 Chevy & GMC OBS Trucks (K1500/C1500)
Looking to upgrade your 1988 to 1998 Chevy or GMC K1500/C1500 with an LS engine? This LS fuel system swap guide for OBS (Old Body Style) trucks covers everything you need to complete your fuel system setup with confidence. Whether you’re doing a return-style or return-less LS swap, we break down all the essential parts, tips, and product links to make your build easier.
Why LS Swap Your OBS 1988–1998 Chevy/GMC Truck?
As C10 trucks become increasingly rare, OBS pickups—especially the 1988–1998 K1500 and C1500—have grown in popularity for performance builds. These trucks make excellent LS swap candidates due to their factory EFI compatibility via the original TBI (Throttle Body Injection) setup. This means you can often reuse the factory fuel tank and sending unit, simplifying the LS swap process and saving you money.
OBS LS Swap Fuel System Advantages
- Factory EFI compatibility – No need to replace your gas tank.
- Easy AN adapter integration – Convert factory fittings to AN6 with simple adapters.
- Cost-effective upgrade path – Use in-tank pumps with higher flow ratings.
- Clean installation – With our AN PTFE hose kits, you get performance and style.
Return-Less LS Swap Fuel System Parts List
If you're using an LS engine with a built-in return-less fuel rail (like many Gen III and IV engines), here's what you'll need:
Fuel Pumps for Return-Less Setup
- Spectra Premium 190LPH Fuel Pump – Supports up to 450HP
- Walbro 255LPH Fuel Pump – Supports up to 550HP
- Aeromotive Stealth 340LPH Pump – For high-horsepower builds
Adapter Fittings
Return-Less LS Swap Kit
- Hot Rod AN Return-Less LS Swap Kit – Includes 20ft braided PTFE hose, AN fittings, optional color choices.
Return-Style LS Swap Fuel System Parts List
For LS engines with a return-style fuel system (dual-line rails), use this configuration:
Fuel Pumps for Return-Style Setup
- Walbro 255LPH Fuel Pump – Drop-in compatible with OBS sending unit
- Aeromotive 340LPH Stealth Pump – For higher-flow applications
Adapter Fittings
Fuel Filters
- Factory-style Filter with AN Adapters
- Aeromotive 10-Micron Filter – Requires 10 ORB to AN fittings
- Holley 10-Micron Filter – Requires 8 ORB to AN fittings
Return-Style LS Swap Kit
- Hot Rod AN Return-Style LS Swap Kit – Includes 30ft of PTFE hose for both feed and return lines.
Frequently Asked Questions (FAQs)
Do I need to replace my fuel tank for an LS swap?
No, the 1988–1998 OBS GM trucks were originally designed for EFI, making them compatible with modern high-pressure pumps using the factory sending unit.
Should I use a return or return-less fuel system?
Use return-less for engines with integrated fuel pressure regulation. Choose return-style setups for dual-line fuel rails and external regulation, especially in higher horsepower applications.
Need Help With Your LS Swap?
If you have questions or need help selecting the right parts, contact us here. Our expert team is ready to assist.
Shop OBS LS Swap Parts
Build Your Fuel System the Right Way
Hot Rod AN LLC makes it easy to get the parts you need for your OBS LS swap. Quality fittings, hose, and support—all in one place.
Shop LS Swap Kits Now
0 comments