LS Swap AN Fuel Line Install Kit — Return-Style (PTFE AN-6)

True return-style fueling for Gen III/IV LS with the regulator built into the fuel rail. This kit gives you PTFE AN-6 hose and matched fittings for both feed and return, plus OEM-style quick-connects for the rail. Result: steady ~58 PSI at the rail, clean routing, and E85-safe plumbing.

What’s in the kit

• PTFE AN-6 hose — choose length (20 / 30 / 40 ft) and color.
• PTFE hose-end fittings (8 total) — 4× straight, 2× 45°, 2× 90°.
• EFI quick-connect adapters — 1× 3/8″ ➝ AN-6 (feed) and 1× 5/16″ ➝ AN-6 (return).
• Rubber-cushioned line clamps (10-pack) — tidy, rattle-free mounting.

How it plumbs (return-style with rail regulator)

1. Tank/Pump ➝ 10 µm (or better) EFI filter ➝ Rail feed (use the 3/8″ quick-connect → AN-6).
2. Rail return outlet ➝ Return line (use the 5/16″ quick-connect → AN-6) ➝ back to tank/sending-unit return port.

The fuel rail’s built-in regulator sets pressure (commonly ~58 PSI). No external/bypass regulator is needed for this layout.

Which length should I choose?

• 20 ft — short wheelbase / tight routing.
• 30 ft — most cars & trucks (sweet spot).
• 40 ft — long wheelbase, heat-avoidance detours, service loops.

Return-style uses two lines—feed and return. If unsure, size up one step.

Required items (not included)

• EFI fuel filter ≤10 µm — use our Factory-Style Inline Filter Kit (AN-6) for stock-ish flow, or pick a high-flow option from the Fuel Filters collection.
• Adapter fittings for the tank sending unit — see AN adapter fittings.
• Adapter fittings for an inline pump (if using) — from the same AN adapter fittings collection.

Recommended add-ons

• Transmission adapter fittings → AN male (if plumbing cooler lines now).
• Extra PTFE hose-end fittings for additional angles or service loops.
• Install tools — PTFE cutter, vise jaws, AN wrenches for clean assembly.

Why this kit works

• PTFE throughout for E85 compatibility, low permeation, and heat resistance.
• Matched ends (4 straight, 2×45°, 2×90°) make routing predictable and leak-free.
• OEM-style quick-connects snap to the rail—no guessing at thread adapters.
• Cushioned clamps keep lines neat and quiet along the frame.

Install instructions & Hose 101

• PTFE hose & AN fittings — step-by-step (cutting, olive install, clocking, torque).
• AN Hose 101 — tech library (filter micron, bend radius, sizing, LS specifics).

FAQs