2005 Subaru WRX Fuel Pump: The Complete Guide to Replacement, Upgrades, and Costs

The bottom line: The 2005 Subaru WRX fuel pump is a critical component that delivers fuel from the tank to the engine, and when it fails, you will experience hard starting, loss of power, or a complete no-start condition. The OEM pump flows approximately 130 liters per hour (lph), which is sufficient for stock power levels, but if you are planning any performance upgrades, you will need a higher-flow aftermarket unit. Replacement costs range from $80 for a basic aftermarket pump to over $600 for a complete OEM assembly, and the job can be done at home in about one hour with basic tools.

Understanding the 2005 Subaru WRX Fuel Pump

The fuel pump in your 2005 Subaru WRX is an electric, in-tank unit. It sits inside the fuel tank and pushes gasoline to the engine at a controlled pressure. The system uses sequential multi-port fuel injection, and the stock pump is designed to maintain proper fuel pressure under all driving conditions.

OEM Specifications

The factory fuel pump for the 2005 WRX has a flow rate of about 130 lph. This is enough for the stock 2.0L turbocharged engine producing around 227 horsepower. The OEM part number for the pump assembly is 42022FE003, which includes the pump and strainer set. The replacement pump part number is 42022FE001. These parts are available through Subaru dealers and online parts retailers.

The fuel tank capacity is 15.9 gallons (60.2 liters), and the system requires premium unleaded gasoline with an octane rating of 91 or higher.

Signs of a Failing Fuel Pump

Knowing the symptoms of a bad fuel pump can save you from being stranded. Here are the most common warning signs:

1. Engine cranks but won't start. This is the most obvious symptom. If you turn the key and the engine turns over but never fires, the fuel pump may have failed. You can check by listening for a faint whirring sound from the rear of the car when you turn the key to the "on" position. If you hear nothing, the pump is likely dead.

2. Loss of power under load. A weak pump cannot deliver enough fuel when you step on the gas. The car may hesitate, stumble, or feel like it is running out of gas, even with a full tank. This is especially noticeable during hard acceleration or when climbing hills.

3. Sputtering at high speeds. If the pump is failing, it may not maintain consistent pressure at higher RPMs. The engine may sputter or surge when you are cruising on the highway.

4. Whining noise from the fuel tank. A healthy fuel pump makes a quiet, steady hum. If you hear a loud whining or droning sound coming from the rear of the car, the pump bearings are wearing out and replacement is imminent.

5. Check engine light. A failing fuel pump can trigger diagnostic trouble codes related to fuel pressure or lean air-fuel mixture. Common codes include P0087 (fuel rail pressure too low) or P0171 (system too lean).

OEM vs. Aftermarket Fuel Pump Options

When it comes time to replace the fuel pump in your 2005 Subaru WRX, you have three main choices: OEM, aftermarket performance, and budget aftermarket.

OEM Subaru Fuel Pump

The genuine Subaru pump is the safest choice. It is designed specifically for your car and will last for many years. The OEM pump assembly (part number 42021FE080) retails for around $387, but you can find it for about $320 from discount Subaru parts dealers. The pump-only option (part number 42022FE011) costs around $253. The complete pump assembly with sending unit (part number 42021SA021) costs nearly $494.

Aftermarket Performance Fuel Pumps

If you have modified your WRX with a larger turbo, bigger injectors, or aftermarket engine management, you will likely need a higher-flow pump. Several reputable brands offer drop-in replacements:

  • Walbro 255 lph: This is the most popular upgrade for 2002-2007 WRX and STI models. It flows 255 liters per hour and is a direct fit. It costs around $185 and comes with an installation kit. This pump was even included as part of the Prodrive Performance Pack on STI models.

  • Walbro 450 lph: For high-horsepower builds, this pump delivers 450 lph. It is also a drop-in replacement for 2002-2007 WRX models.

  • AEM 340 lph: This pump supports over 1,000 horsepower and is a direct fit for 2002-2007 WRX and 2004-2007 STI models.

  • DeatschWerks DW100 (165 lph): Designed as an OE replacement with a mild upgrade. It is quieter than the stock pump and compatible with ethanol fuels.

Budget Aftermarket Options

Several brands offer affordable replacements that work well for stock or mildly modified cars. These pumps often cost between $50 and $80. While they may not have the same longevity as OEM or premium aftermarket units, they can be a good temporary fix.

How to Replace the Fuel Pump in a 2005 Subaru WRX

Replacing the fuel pump is a straightforward job that most DIYers can handle in about an hour. Here is a step-by-step guide.

What You Will Need

  • New fuel pump (OEM or aftermarket)
  • Fuel pump installation kit (includes filter, clamps, wiring pigtail)
  • Fuel pump tank seal gasket (part number 42060AA040, about $8)
  • Flathead and Phillips screwdrivers
  • 10mm and 12mm sockets
  • Ratchet and extensions
  • Shop rags
  • Safety glasses and gloves
  • Fire extinguisher (always a good idea when working with fuel)

Step 1: Relieve Fuel System Pressure

Locate the fuel pump fuse in the under-dash fuse box. Remove the fuse. Start the engine and let it run until it stalls. Crank it a few more times to make sure all pressure is gone. Turn the ignition off and reinstall the fuse.

Step 2: Access the Fuel Pump

The fuel pump is located under the rear seat. Remove the rear seat bottom cushion by pulling up on the front edge. You will see a metal access cover on the floor. Remove the screws holding the cover and lift it off.

Step 3: Disconnect the Old Pump

Unplug the electrical connector. Use a fuel line disconnect tool or a flathead screwdriver to release the fuel lines. Have a rag handy to catch any residual fuel. Remove the locking ring by tapping it counterclockwise with a hammer and screwdriver. Lift the pump assembly out of the tank.

Step 4: Swap the Pump

Remove the old pump from the bracket assembly. Transfer the rubber grommet and fuel sock to the new pump. Install the new pump into the bracket. Make sure the wiring is routed correctly and the pump sits securely.

Step 5: Reinstall

Lower the new assembly into the tank. Make sure the float arm is not bent and the gasket is seated properly. Install the locking ring and tighten it clockwise. Reconnect the fuel lines and electrical connector. Replace the access cover and rear seat.

Step 6: Test

Turn the key to the "on" position (do not start) and listen for the pump to prime. It should run for about two seconds and then stop. Check for fuel leaks at the connections. Start the engine and verify proper operation.

Fuel Pump Replacement Cost

The cost to replace the fuel pump on a 2005 Subaru WRX varies widely depending on the parts you choose and whether you do it yourself or hire a shop.

  • DIY with budget aftermarket pump: $50 to $100
  • DIY with Walbro 255 lhp upgrade pump: $160 to $200
  • DIY with OEM pump: $250 to $400
  • Professional installation with OEM parts: $800 to $1,250

According to Fixter, a fuel pump replacement for a Subaru WRX in the UK costs between £798 and £1,254, which is roughly $1,000 to $1,600 USD. A replacement pump assembly from Subaru can cost as much as $637 for the turbo model.

When to Upgrade Instead of Replacing

If your stock 2005 WRX fuel pump has failed, you have the perfect opportunity to upgrade. Here are the scenarios where an upgrade makes sense:

1. You have a larger turbocharger. The stock pump cannot keep up with the fuel demands of a bigger turbo. A Walbro 255 lph pump is the minimum recommended upgrade for stage 2 or stage 3 power levels.

2. You are running E85. Ethanol requires about 30% more fuel flow than gasoline. Even a basic E85 tune will exceed the capacity of the stock pump. A Walbro 450 lph or AEM 340 lph pump is recommended for E85 setups.

3. You plan to upgrade injectors. Larger injectors need a pump that can supply enough volume. The stock pump will be a bottleneck.

4. You want reliability. An aftermarket pump like the Walbro is often more durable than the aging factory unit. Many owners report these pumps lasting well over 100,000 miles without issues.

Common Mistakes to Avoid

Using the wrong fuel sock. Some aftermarket pumps come with a universal filter that does not fit the WRX correctly. You may need to reuse the original Subaru fuel sock, which has a hard plastic skeleton that prevents the pump from ingesting the soft bag filter.

Forgetting to replace the gasket. The fuel pump tank seal (part number 42060AA040) should always be replaced. It costs about $8 and prevents fuel smells and leaks. Many Walbro kits offer an optional genuine Subaru gasket for this reason.

Not checking the fuel pump driver module. The 2005 WRX has a fuel pump control module (part number 22648AA011) that can also fail. If the pump is not getting power, the module may be the problem, not the pump itself.

Overtightening the locking ring. The plastic retaining ring can crack if you use too much force. Hand-tighten it with a screwdriver and hammer, then give it one or two more taps. Do not use an impact tool.

Recommended Maintenance

The fuel system on the 2005 WRX should be inspected every 30,000 miles. This includes checking the fuel filter, inspecting lines for leaks, and testing fuel pressure. At 60,000 miles, consider replacing the fuel pump if it has never been changed. Many owners replace the pump proactively when they do other fuel system work.

Using high-quality fuel and changing the fuel filter regularly will extend the life of your fuel pump. Avoid running the tank below a quarter full, as this can cause the pump to overheat and suck up debris from the bottom of the tank.

Why Choose KEMSO for Your Fuel Pump Replacement

When it comes time to replace the fuel pump in your 2005 Subaru WRX, KEMSO offers an outstanding option that combines performance, reliability, and value.

KEMSO fuel pumps are high-performance, OEM replacement units designed to meet or exceed the specifications of the original equipment. They are engineered as direct-fit replacements, meaning you do not need special tools or adapter kits to install them. The pump fits perfectly into the stock fuel pump hanger assembly, making the swap quick and straightforward.

Each KEMSO fuel pump is backed by a lifetime warranty. This is a rare and valuable benefit in the automotive parts industry. If your KEMSO pump ever fails due to a manufacturing defect, you will receive a replacement at no cost. This warranty covers a wide range of vehicles, including the Subaru Impreza (1998-2023).

KEMSO pumps deliver reliable fuel flow for daily driving and mild performance applications. They are built with quality materials and undergo individual testing to ensure consistent performance. For a 2005 Subaru WRX that sees regular street use, a KEMSO fuel pump is a smart, cost-effective choice.

Visit KEMSO Racing today to see the full selection of fuel pumps for your Subaru and other vehicles. Their website offers complete fitment information, customer reviews, and technical support. Order with confidence and get your WRX back on the road with a pump you can trust.

Visit KEMSO Racing: https://www.kemsoracing.com/


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