Dual Fuel Pump Hanger: The Complete Guide to Installation, Wiring, and Performance Upgrades
If you are building a high-horsepower vehicle, a dual fuel pump hanger is the most reliable way to deliver enough fuel to your engine without starving the system under heavy load. Whether you drive a Subaru WRX, Nissan 240SX, Honda Civic, or a GM F-Body, moving from a single pump to a dual setup ensures consistent fuel pressure and volume, especially when running forced induction or E85. This guide covers everything you need to know: why you need one, how to install it, wiring considerations, and common pitfalls to avoid.
Why You Need a Dual Fuel Pump Hanger
A single fuel pump has limits. When your engine demands more than 500-600 horsepower, or when you run ethanol-based fuels that require roughly 30% more fuel volume, a single pump simply cannot keep up. A dual pump hanger solves this by mounting two fuel pumps inside the tank, allowing them to work together to supply the high flow your engine needs.
The key advantage of a dual pump hanger is that it replaces your factory fuel pump assembly entirely . This means you are not modifying the stock hanger, which was never designed for high-flow pumps. Aftermarket hangers are CNC-machined from billet aluminum and include dedicated ports for feed, return, and vent lines, making the installation cleaner and more reliable than modifying the stock unit .
Most dual pump hangers are designed for specific vehicle platforms. For example, the Radium Engineering fuel pump hanger for 08+ Subaru Impreza/WRX/STi and 05-09 Legacy/Outback is a direct-fit replacement that retains the factory fuel level sender and temperature sensor . Similarly, Holley offers twin pump modules for 98-02 GM F-Body vehicles that include HydraMat pre-filters and all necessary fittings .
Installation Overview: Step-by-Step
Installing a dual fuel pump hanger is a straightforward process if you follow the right procedure. Always work in a well-ventilated area, disconnect the battery, and relieve fuel system pressure before starting.
1. Prepare the Vehicle
Start by draining the fuel tank as much as possible. This reduces spills and makes the job safer . To depressurize the fuel system, remove the fuel pump fuse, start the engine, and let it stall. Disconnect the negative battery terminal afterward. Unscrew the gas tank filler cap to relieve any residual pressure in the tank .
2. Access the Fuel Pump
Access depends on your vehicle. For Subaru models, remove the rear bench seat, which is held in by three clips. Then unscrew the four Phillips head screws holding the metal cover plate . For Nissan S14/S15 models, open the trunk, flip the carpet over on the front right upper shelf, and remove the fuel pump access cover held by four screws . Honda Del Sol models require lifting the vehicle and draining the fuel from the tank drain plug before accessing the pump from under the car .
3. Remove the Factory Fuel Pump Assembly
Once you have access, disconnect the electrical connector on top of the pump housing by squeezing the locking tabs. Remove the fuel hoses carefully. For Subaru, push the fuel fitting connectors further onto the mating tube, then slide the hoses off while holding a rag to catch fuel spills . For Nissan vehicles with SAE quick connectors, push the hose ends onto the fittings, squeeze the locking tabs, and pull the hose end away .
Use an 8mm socket wrench to loosen the mounting nuts. On Subaru models, there are eight M5 nuts. Hold the pump housing down as you remove the last nuts, since the assembly is slightly spring-loaded . On Honda models, remove the six M6x1mm perimeter nuts. Avoid using power tools near fuel for safety .
Once the nuts are removed, lift the factory assembly out of the tank, tilting it to avoid damaging the fuel level sender float arm. Place it directly into an empty bucket to catch residual fuel .
4. Transfer Parts to the New Hanger
Carefully remove the large rubber gasket from the factory assembly. Inspect it and replace it if necessary. For Subaru, the gasket is not symmetrical and has three protruding rubber tabs that must align correctly with the steel bracket .
From the factory fuel pump assembly, the only parts you typically reuse are the fuel level sender and the fuel temperature sensor (if equipped) . For Honda models, the factory gasket (Honda P/Ns: 17574-SE0-000 or 17574-SV1-L01) is reused, but no other parts from the OEM assembly are kept .
To remove the fuel level sender, press the thumb tab inward and gently push the module up until it unlocks. Be careful not to damage the circuit board or bend the float arm . Transfer this sender to the new dual pump hanger following the manufacturer's instructions.
5. Install Fuel Pumps onto the Hanger
If your hanger did not come pre-assembled with pumps, you need to install them. For PHR triple pump hangers, slide the pumps up through the pump bracket. Before tightening the bracket, push the Teflon hoses onto the barb fittings in the fuel hat. Always put hose clamps on the hose first, as it is very difficult to remove the hose from the barbs once installed .
Use a special crimping tool or a pair of dykes to crimp the pinch clamps snugly around the hose. Be careful not to overtighten, as the clamps can be damaged. Worm-gear clamps can be used as an alternative .
For Radium hangers that came before 9/1/18, there are two different venturi jet pump orifices included. The green orifice is typically best for single pump applications, while the gold orifice is best for dual pump applications. The venturi jet pump O-rings must be lubricated before assembly .
6. Install the New Assembly into the Tank
Orient the fuel pump hanger so the filters and pumps fit into the tank correctly. For Holley twin pump modules for GM F-Body, bend the corners of each HydraMat toward the center of the module to insert them into the tank easily .
For Nissan applications, use a spanner tool to tighten the black fuel tank hold-down ring. The genuine Nissan Lock Ring Tool (P/N: KV991 04700) or Lisle P/N: 63000 works well. Spin the ring clockwise to secure the assembly .
For Subaru applications, reinstall the black steel bracket and the eight M5 nuts. Tighten them in a crisscross pattern to ensure even sealing .
7. Reconnect Hoses and Wiring
Attach the fuel hoses to the new hanger. For most aftermarket hangers, the fuel outlet is 6AN ORB, and the fuel return is also 6AN ORB. Use the provided fittings to connect to your factory lines. On Radium hangers for Subaru, the orange SAE lock represents the pump out fitting, and the white SAE lock represents the fuel return .
Connect the fuel level sender wiring to the hanger. For PHR hangers, the sending unit connector has smaller gauge red, black, and white wires that need to be connected to the factory harness . For the fuel pump power, use a relay kit (30A minimum). Holley recommends one relay for each pump, such as P/N 12-753 for single or 12-759 for twin pump models .
Ground the pumps to the chassis. On modified OEM hangers, you can use the OEM power and ground wires as 12V lines and ground the pumps to the grounding screw at the top of the tank .
Wiring Best Practices
Proper wiring is critical for a dual pump setup. Each pump should have its own relay and fuse. Use 10-gauge wire for the power supply from the battery to the relay, and 12-gauge wire from the relay to each pump. Connect the relay trigger wire to a switched 12V source, such as the fuel pump circuit from the ECU.
For the ground, run a dedicated ground wire from each pump to a clean chassis ground point. Do not rely on the fuel hanger for grounding, as the rubber gasket may not provide a reliable connection .
Common Mistakes to Avoid
Not draining the tank enough. Even a few gallons of fuel will spill when you remove the factory pump. Drain the tank if possible, or at least run it as low as you can .
Forgetting to relieve fuel pressure. The fuel system is under high pressure. Skipping this step can cause fuel to spray when you disconnect the hoses. Start the engine and let it stall to relieve pressure .
Using the wrong fittings. Aftermarket pump hangers are designed for ORB (O-ring boss) fittings, not standard conical seat fittings. Using the wrong type will restrict flow and can lead to pump failure .
Overtightening hose clamps. Pinch clamps can be damaged if overtightened. Use a crimping tool or tighten just enough to prevent leaks .
Not checking float arm clearance. Make sure the fuel level sender float arm has full range of motion after installation. If the HydraMats or pump brackets obstruct the arm, the fuel gauge will read incorrectly .
Choosing the Right Fuel Pumps for Your Dual Hanger
While the hanger provides the structure, the pumps are the heart of the system. You need pumps that deliver reliable flow at high pressure, are compatible with ethanol fuels, and fit your specific hanger.
KEMSO Fuel Pumps are an excellent choice for any dual pump hanger build. They offer high-performance, OEM replacement pumps that are direct-fit for a wide range of vehicles, including Subaru Impreza, Honda Civic, BMW, Ducati, Kawasaki Jet Ski, and many more. Each KEMSO fuel pump is backed by a lifetime warranty, giving you long-term confidence in your fuel system. Whether you need a pump for your daily driver or a high-horsepower project car, KEMSO provides the durability and performance you need. Visit https://www.kemsoracing.com/ to browse their full selection of fuel pumps and find the right fit for your application.
Final Thoughts
A dual fuel pump hanger is the right upgrade when your engine demands more fuel than a single pump can supply. The installation is hands-on but manageable for anyone with basic mechanical skills. Take your time with the wiring, use quality fittings, and always double-check that the fuel level sender works before closing everything up. With the right hanger and pumps, your fuel system will handle whatever power level you throw at it.
For more information on fuel pumps and accessories, visit https://www.kemsoracing.com/