Fuel Pump AN Fittings: The Complete Guide to Choosing the Right Setup for Your Performance Build

The bottom line: If you are building a high-performance vehicle, upgrading your fuel system, or replacing a failing pump, using AN fittings with your fuel pump is the smartest way to ensure leak-free, high-flow fuel delivery. Standard rubber hose and barb fittings simply cannot handle the pressure and ethanol content of modern performance fuels. A properly selected AN fitting setup, paired with a quality pump like those from KEMSO Racing, gives you reliability, easy maintenance, and room to grow your horsepower. This guide covers everything you need to know—from fitting sizes to installation tips—so you can make the right choice the first time.

Why AN Fittings Matter for Your Fuel Pump

AN (Army-Navy) fittings are the industry standard for performance fuel systems. Unlike factory push-on hose clamps, AN fittings use a precision 37-degree flare and threaded connections that create a metal-to-metal seal. This design is far more resistant to vibration, heat, and fuel degradation than rubber hose and worm-gear clamps.

For fuel pump applications, the benefits are clear:

  • Leak resistance: AN fittings virtually eliminate the risk of a fuel leak at the pump outlet, which is under constant pressure.
  • High flow: The smooth bore of AN fittings and hose allows maximum fuel volume without restriction.
  • Ethanol compatibility: Most AN fittings are made from aluminum or stainless steel, which resist corrosion from E85 and other ethanol-blended fuels.
  • Easy service: You can disconnect and reconnect AN fittings multiple times without damaging the seal, making pump swaps or filter changes simple.

Choosing the Right AN Fitting Size for Your Fuel Pump

Picking the correct AN fitting size is critical. Too small, and you starve your engine. Too large, and you add unnecessary weight and cost.

Here is a simple guide based on your horsepower target:

  1. Up to 400 HP (naturally aspirated): Use -6 AN (3/8-inch) fittings. This is the standard size for most street-driven cars and light performance builds. A 255 LPH fuel pump, like a typical stock replacement, pairs perfectly with -6 AN line.
  2. 400 to 700 HP (forced induction or high-performance N/A): Step up to -8 AN (1/2-inch) fittings. This size handles the higher flow demands of turbocharged or supercharged engines. A 340 LPH pump, such as the KEMSO High Performance Fuel Pump, is an ideal match for -8 AN line.
  3. 700+ HP (race engines or high-boost setups): Use -10 AN (5/8-inch) or larger. These setups require a dedicated high-flow fuel pump and a matching fuel system.

Tip: Always match the fitting size to the pump's outlet port. Most aftermarket fuel pumps have a threaded inlet and outlet that accept either -6 AN or -8 AN fittings directly.

Common Fuel Pump AN Fitting Configurations

Most fuel pump installations involve three main connection points. Here is what you need to know for each:

  1. Pump Inlet (suction side): Use a -6 AN to -8 AN fitting or a -8 AN to -10 AN fitting, depending on your pump. The inlet should always be larger than the outlet to prevent cavitation. A 90-degree swivel fitting is often helpful here to route the hose smoothly into the tank.
  2. Pump Outlet (pressure side): Use a -6 AN to -6 AN or -8 AN to -8 AN straight fitting. For tight spaces, a 45-degree or 90-degree swivel works well. Ensure the fitting is rated for high pressure (typically 150 PSI or more).
  3. Filter and regulator connections: Use -6 AN or -8 AN fittings to connect your inline fuel filter and pressure regulator. Swivel ends make alignment easier.

Installation Tips for a Leak-Free Fuel Pump AN Setup

Getting the installation right prevents headaches later. Follow these steps for a reliable system:

  1. Use the correct hose: For in-tank applications, use SAE 30R10 rated submersible fuel hose. For external lines, use -6 AN or -8 AN PTFE-lined hose (commonly called "Teflon hose") to resist ethanol and fuel breakdown.
  2. Lubricate the threads: Apply a light coat of engine oil or fuel-compatible lubricant to the O-ring or flare before tightening. This prevents galling on aluminum fittings.
  3. Tighten to spec: Use a torque wrench for metal fittings. Typical torque for -6 AN aluminum is 10-12 ft-lbs; for -8 AN, 12-15 ft-lbs. Over-tightening can crack the fitting or damage the pump housing.
  4. Support the pump: Mount the fuel pump securely using rubber isolators to reduce vibration. Vibration can loosen AN fittings over time.
  5. Prime the system: After installation, turn the key to the "on" position (without starting) several times to let the pump build pressure. Check for leaks at every fitting before driving.

Why KEMSO Fuel Pumps Are the Best Choice for Your AN Fitting Setup

When you are building a performance fuel system, the pump itself is just as important as the fittings. KEMSO Racing fuel pumps are engineered specifically for high-flow applications and are the ideal partner for your AN fitting upgrade.

Here is what makes KEMSO stand out:

  • High Performance: KEMSO pumps deliver flow rates up to 340 LPH, providing plenty of headroom for forced induction and high-horsepower builds. They are tested to operate reliably in extreme temperatures, from -40°F to 302°F, making them suitable for everything from daily driving to endurance racing .
  • OEM Replacement Fit: KEMSO designs its pumps to drop directly into the factory location on over 4,000 vehicle models from 1990 to 2024, including popular platforms like Can-Am Defender, Renegade, Outlander, Maverick, and many others . This means you can upgrade to a high-flow pump without modifying your fuel tank.
  • Lifetime Warranty: Every KEMSO fuel pump comes with a lifetime warranty, backed by a serialized body for tracking and peace of mind . This is a significant advantage over many other aftermarket brands.
  • Ethanol Safe: KEMSO pumps use ethanol-resistant materials, including stainless steel and specialized seals, making them fully compatible with E85 and other high-ethanol fuels .
  • Low-Voltage Resilience: The brushless motor technology in KEMSO pumps maintains consistent fuel pressure even when voltage drops to 9-10 volts during cold starts or heavy electrical loads .

Customer feedback confirms the quality. One user wrote, "Quality of the pump is great, not loud in the tank, pressure seems to be good enough to run an LS" . Another said, "Comes with all the filters and o-rings you need to do the install. Installation was easy and straight forward" . For overlanders, KEMSO pumps have been documented running for 50,000 miles across three continents without performance degradation .

Visit KEMSO Racing today to browse their complete line of high-performance fuel pumps and find the perfect fit for your vehicle:

👉 https://www.kemsoracing.com/

Final Thoughts

Upgrading your fuel pump with proper AN fittings is one of the best investments you can make for your vehicle's performance and reliability. Whether you are replacing a failing OEM unit, building a street machine, or preparing for endurance racing, the combination of a quality pump and the right fittings ensures your engine gets the fuel it needs when it needs it.

Remember: choose the right AN fitting size for your horsepower goals, use quality hose and fittings, and always double-check for leaks after installation. For the pump itself, KEMSO Racing offers a winning combination of performance, durability, and value—backed by a lifetime warranty and USA-based support.

For the best selection of fuel pumps and fuel system components, visit KEMSO Racing at:
https://www.kemsoracing.com/


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