Best Fuel Pump for Subaru STI from Rally Sport Direct

If you’re like me, constantly chasing that next performance milestone with your Subaru STI, you know every component matters. The fuel pump, often an overlooked hero, is absolutely crucial for delivering the consistent, high-pressure fuel your engine needs, especially when you start adding modifications that push the horsepower limits. I’ve spent my fair share of time under the hood, upgrading everything from turbos to injectors, and I’ve learned firsthand that a weak or unreliable fuel pump can quickly become the bottleneck in your build. That’s why diving deep into options for the best fuel pump for Subaru STI from Rally Sport Direct (or similar trusted sources) is so important. We’re not just looking for a replacement; we’re looking for an upgrade that supports your performance goals, whether you’re daily driving or hitting the track. In this guide, I’ll walk you through several popular fuel pump options, sharing what I’ve learned about their real-world performance, fitment, and who they’re really best for.

IMAGE	PRODUCT NAME	AMAZON LINK
	KEMSO 340LPH High Performance Fuel Pump for Subaru/Honda…	View on Amazon
	KEMSO 340LPH High Performance Fuel Pump for Subaru/Honda…	View on Amazon
	Electric Fuel Pump Assembly FIT Subaru Impreza 2008–2011,…	View on Amazon
	SYKRSS E8651M Eletric Fuel Pump Assembly Compatible with…	View on Amazon
	PHILTOP FG1350 Fuel Pump Assembly for Subaru Outback…	View on Amazon
	GPP Gasoline Automatic Fuel Pump for Subaru B9 Tribeca,…	View on Amazon

Product Reviews

KEMSO 340LPH High Performance Fuel Pump for Subaru/Honda…

This KEMSO 340LPH pump is often a go-to choice for enthusiasts looking to significantly boost their fuel delivery without breaking the bank. From my experience, a 340LPH pump is where you want to start for many modified STIs, especially if you’re running larger injectors and a bigger turbo. It’s a workhorse designed to handle serious power, ensuring your engine gets enough fuel even under heavy load. The fact that it’s designed for gasoline or E85 makes it a versatile option for those considering alternative fuels, which is a big plus for high-power builds. Plus, the USA-based support and lifetime warranty from Kemso really give you peace of mind, which is invaluable when you’re relying on a critical component like a fuel pump.

• Supports up to 600 BHP in N/A, Turbocharged, and Supercharged applications
• USA-based support and technicians
• Designed for gasoline or E85 compatibility
• Bypass valve set at 125.8psi, higher than many common pumps
• Serialized fuel pump body guarantees a lifetime warranty

Pros:
– High flow rate suitable for heavily modified STIs
– E85 compatible, offering flexibility for fuel choice
– Excellent warranty and USA-based support
– Competitive price for its performance output

Cons:
– Installation may require some wiring or minor modifications for certain STI models (not always a direct drop-in for every generation)
– Can be slightly louder than OEM pumps, though often negligible in a performance car

Best for: Modified Subaru STI owners aiming for 400-600 horsepower, running E85, or seeking a reliable, high-flow pump with strong warranty support.

User feedback summary: Many users praise its consistent performance, especially on E85, and appreciate the lifetime warranty. Some note that it might be a bit noisy, but generally consider it a good value for the power it supports.

KEMSO 340LPH High Performance Fuel Pump for Subaru/Honda…

Much like its twin listed above, this KEMSO 340LPH pump stands as a robust contender for anyone needing a significant upgrade to their fuel system. It boasts the same impressive features, making it ideal for high-horsepower Subaru STI builds. The ability to support up to 600 BHP means you’ve got plenty of headroom for future modifications, and its compatibility with both gasoline and E85 ensures you’re ready for whatever fuel you decide to run. For me, knowing a company stands behind their product with a lifetime warranty on a serialized pump body is a huge confidence booster, especially when you’re pushing your car to its limits. This pump truly focuses on delivering consistent fuel pressure and flow, which is paramount for engine health and performance in a high-strung STI.

• Supports up to 600 BHP in N/A, Turbocharged, and Supercharged applications
• USA-based support and technicians
• Designed for gasoline or E85 compatibility
• Bypass valve set at 125.8psi, providing ample pressure
• Serialized fuel pump body guarantees a lifetime warranty

Pros:
– High flow rate is excellent for highly tuned STIs
– Versatile for use with both gasoline and E85
– Backed by a strong lifetime warranty and responsive USA support
– Offers great performance value for modified vehicles

Cons:
– May require minor modification for certain STI bucket assemblies
– Similar to other high-flow pumps, can have a slightly audible hum compared to stock

Best for: Subaru STI owners seeking a robust, future-proof fuel pump for substantial power gains (400-600hp) with E85 flexibility and a commitment to long-term reliability.

User feedback summary: Users report strong, reliable performance, particularly for tuned applications. The lifetime warranty is frequently mentioned as a major selling point, reassuring customers about its durability.

Electric Fuel Pump Assembly FIT Subaru Impreza 2008–2011,…

Now, let’s shift gears a bit. While the title focuses on the “Best Fuel Pump for Subaru STI,” not every pump is built for high-performance STI demands. This Electric Fuel Pump Assembly is a direct OEM-style replacement designed for specific Subaru models like the Impreza (non-STI), Legacy, and Outback with the 2.5L H4 engine. It’s engineered to match the original factory specifications for flow rate and pressure, which is perfect if your stock pump has failed and you just want to get your daily driver back on the road without any performance upgrades. It’s a pre-assembled, drop-in unit, meaning installation is usually straightforward with no cutting or splicing, making it an excellent choice for a hassle-free repair. However, it’s crucial to understand that this pump likely will not provide the increased fuel flow and pressure required by a modified Subaru STI, which typically demands much higher performance from its fuel system.

• Direct fit for 2008-2011 Subaru Impreza (2.5L H4), 2006-2009 Subaru Legacy (2.5L H4), 2006-2009 Subaru Outback (2.5L H4)
• Replaces OE part numbers E8651M, P76427M
• Engineered to match OEM connector, flow rate, and pressure output
• Built with ethanol-resistant components and integrated float sensor
• Pre-assembled for drop-in installation

Pros:
– Easy, direct-fit installation for specified models
– Restores original fuel system pressure and smooth idle
– Cost-effective OEM replacement
– Ethanol-resistant components for modern fuels

Cons:
– Not suitable for performance Subaru STI applications
– Lower flow rate compared to performance pumps
– Does not offer any performance upgrade potential

Best for: Owners of stock 2008-2011 Subaru Impreza (non-STI), 2006-2009 Legacy, or 2006-2009 Outback 2.5L H4 looking for a reliable, direct-replacement fuel pump to restore factory performance.

User feedback summary: Users commend its easy installation and perfect fit for the listed vehicles, reporting that it successfully resolved fuel delivery issues and restored normal operation without any fuss.

SYKRSS E8651M Eletric Fuel Pump Assembly Compatible with…

The SYKRSS E8651M fuel pump assembly is another excellent option for those seeking an OE-standard replacement for specific Subaru models. It directly replaces several OE part numbers, making it a reliable choice when your stock pump gives out. Its primary focus is on restoring optimal fuel pressure and flow to match the original factory specifications, which is essential for maintaining fuel efficiency and consistent power output in a stock engine. While it aims for optimized fuel efficiency, it’s important to clarify that this pump is designed for stock 2.5L H4 Impreza, Legacy, and Outback models, not the high-demand environment of a performance Subaru STI. However, for its intended application, it offers a 1-year unlimited-mileage quality guarantee, which is a nice touch for peace of mind.

• Replaces multiple OE numbers like ‎42021AG110, E8651M, P76427M
• Direct fit for 2008-2011 Subaru Impreza (H4 2.5L), 2006-2009 Subaru Legacy (H4 2.5L), 2006-2009 Subaru Outback (H4 2.5L)
• Designed to meet or exceed OE specifications in quality, fit, and function
• Optimized fuel pressure and flow for stock engine efficiency
• 1-year unlimited-mileage quality guarantee

Pros:
– Reliable OE-standard replacement for specific models
– Helps restore optimal fuel efficiency and power for stock engines
– Good warranty for an OEM-style part
– Quiet operation and durable materials for longevity

Cons:
– Not suitable for performance Subaru STI applications due to insufficient flow for modified engines
– Limited to specific 2.5L H4 Subaru models, not universal
– No performance upgrade over stock

Best for: Owners of 2008-2011 Subaru Impreza (non-STI), 2006-2009 Legacy, or 2006-2009 Outback 2.5L H4 in need of a dependable, quality replacement that matches factory specifications.

User feedback summary: Customers frequently mention its perfect fit and function, stating that it effectively resolves fuel system issues and operates quietly, providing a reliable OE-equivalent solution.

PHILTOP FG1350 Fuel Pump Assembly for Subaru Outback…

Moving to an older generation of Subaru vehicles, the PHILTOP FG1350 Fuel Pump Assembly is specifically designed as a direct replacement for various 2000-2004 Outback, 2000-2003 Legacy, and 2003 Baja models. This unit focuses on offering a high-quality, long-lasting solution for these specific vehicles, ensuring they perform as they did from the factory. One impressive aspect is its focus on low noise operation (as low as 48dB) and a robust 3500-hour life test, indicating a commitment to durability and quiet performance. While these are great qualities for a replacement pump, it’s very important to note its fitment is for older, typically naturally aspirated or mildly tuned Subaru models, making it completely unsuitable for the performance demands of a modern Subaru STI.

• Direct replacement for 2000-2004 Outback, 2000-2003 Legacy, and 2003 Baja models
• Meets OE standard, interchangeable with FG1350 and other OE numbers
• Made with imported high-performance POM raw materials, ethanol resistant
• Generates noise as low as 48dB and made a 3500-hour life test with less than 15% flow decay
• Easy to install, pre-assembled unit

Pros:
– Excellent durability and long life due to quality materials and rigorous testing
– Very quiet operation compared to many aftermarket pumps
– Ethanol-resistant components for modern fuel compatibility
– Hassle-free direct installation for specified older models

Cons:
– Absolutely not compatible or suitable for Subaru STI models
– Flow rate is insufficient for any performance-oriented build
– Limited to specific older Subaru models

Best for: Owners of 2000-2004 Subaru Outback, 2000-2003 Legacy, or 2003 Baja models who need a durable, quiet, and direct-fit OEM-style replacement fuel pump.

User feedback summary: Users appreciate the straightforward installation and the quiet operation of this pump, often noting that it solved their fuel delivery issues for their specific older Subaru models effectively.

GPP Gasoline Automatic Fuel Pump for Subaru B9 Tribeca,…

Finally, we have the GPP Gasoline Automatic Fuel Pump, which caters to an entirely different segment of the Subaru family: the H6-3.0L and H6-3.6L engines found in the Tribeca, Legacy, and Outback. This is another example of a specialized OEM-style replacement designed to meet the factory specifications for these larger, non-turbo, six-cylinder engines. It’s built to restore the original fuel system functionality and reliability. While it serves its purpose well for these models, providing reliable fuel delivery, its design and flow characteristics are tailored for the H6 engine’s needs, which are distinct from the high-pressure, high-flow requirements of a turbocharged Subaru STI. Therefore, this pump is definitely not a suitable option for an STI, particularly not one that’s been modified for performance.

• Fits 2006-2007 Subaru B9 Tribeca H6-3.0L
• Fits 2008-2012 Subaru Tribeca H6-3.6L
• Fits 2008-2009 Subaru Legacy H6-3.0L
• Fits 2006-2009 Subaru Outback H6-3.0L
• Designed for specific H6 Subaru engine applications

Pros:
– Reliable OEM-style replacement for specific H6 Subaru models
– Restores original fuel system performance
– Direct fit for listed vehicles
– Good for maintaining stock performance in larger Subaru engines

Cons:
– Completely incompatible and unsuitable for Subaru STI models
– Flow rate is not sufficient for any performance STI application
– Only fits specific H6 engine configurations

Best for: Owners of Subaru B9 Tribeca, Tribeca, Legacy H6-3.0L, or Outback H6-3.0L/3.6L models who need a direct-fit replacement fuel pump to maintain stock functionality.

User feedback summary: Customers report that this pump fits perfectly and performs as expected for their Tribeca, Legacy, or Outback H6 models, resolving existing fuel delivery issues.

Helpful Comparison Insights

When you’re looking for the best fuel pump for your Subaru STI from Rally Sport Direct, or any performance outlet, it’s crucial to understand the difference between a high-performance upgrade and a standard OEM replacement. As we’ve seen, not all “Subaru fuel pumps” are created equal, especially when it comes to supporting an STI.

The KEMSO 340LPH pumps clearly stand out as the only true performance options in this list. They offer a significantly higher flow rate (340LPH) and are explicitly designed to support up to 600 BHP, making them suitable for heavily modified STIs running larger turbos and injectors, and even E85 fuel. Their lifetime warranty and USA-based support add incredible value and peace of mind. For an STI, especially one that’s been tuned, these KEMSO pumps are the kind of performance upgrade you need to prevent fuel starvation and ensure consistent power delivery.

On the other hand, the Electric Fuel Pump Assembly, SYKRSS E8651M, PHILTOP FG1350, and GPP Gasoline Automatic Fuel Pump are all categorized as OEM-style replacement units. While they are excellent for their intended applications – restoring stock functionality in specific, non-STI Subaru models like the Impreza 2.5L, Legacy, Outback, or Tribeca H6 – they are not designed for, nor capable of, meeting the performance demands of a Subaru STI. Their flow rates and pressure outputs match factory specifications for stock engines, which are far below what a modified STI requires. Installing one of these in a performance STI would likely lead to fuel starvation, engine damage, and a very disappointing driving experience.

So, when making your decision, always prioritize the pump’s flow rate and its stated horsepower support if you own a Subaru STI. Look for pumps that explicitly mention compatibility with high-performance applications or E85 if that’s your goal. The OEM replacements are fantastic for fixing a daily driver’s fuel issue, but they simply don’t belong in a performance STI.

Final Verdict

Choosing the right fuel pump for your Subaru STI is a decision that directly impacts performance, reliability, and the overall health of your engine. After reviewing these options, it’s clear there’s a significant distinction between performance-oriented pumps and direct OEM replacements.

For those of us with a Subaru STI that’s stock or has light modifications, and you’re just looking for a robust, slightly-over-stock replacement without major power goals, a quality 255LPH pump (like a Walbro 255, though not featured here) is often a reliable first step, but the KEMSO 340LPH would provide plenty of headroom.

However, if you own a modified Subaru STI, especially one pushing beyond 350-400 horsepower, running E85, or planning significant future upgrades, the KEMSO 340LPH High Performance Fuel Pumps are undoubtedly the best choice among the options we’ve reviewed for providing the necessary fuel flow. Their robust design, E85 compatibility, high flow rate, and impressive lifetime warranty make them a stellar investment for any serious STI enthusiast. They offer the confidence and capability needed to support substantial power figures, making them a true upgrade.

The other listed fuel pump assemblies (Electric Fuel Pump Assembly, SYKRSS E8651M, PHILTOP FG1350, GPP Gasoline Automatic Fuel Pump) are excellent for their specific, non-STI Subaru applications as OEM replacements. They’ll get your daily driver back on the road reliably and affordably. But for a Subaru STI, particularly one from Rally Sport Direct’s performance-focused customer base, these simply won’t cut it. Don’t compromise on fuel delivery for your STI; it’s the lifeline of your engine.

Comprehensive FAQ Section

Q1: Why is upgrading my fuel pump important for my Subaru STI?
A1: Upgrading your fuel pump for your Subaru STI is crucial because the stock pump often can’t deliver enough fuel to support increased horsepower from modifications like larger turbos, injectors, or E85 fuel. A high-performance pump ensures your engine gets the consistent, high-pressure fuel it needs, preventing fuel starvation, engine damage, and allowing for optimal tuning and power output.

Q2: What flow rate (LPH) should I look for in the best fuel pump for a modified Subaru STI?
A2: For most modified Subaru STIs, especially those aiming for 350-600 horsepower, a fuel pump with a flow rate of 340LPH (Liters Per Hour) or higher is generally recommended. Pumps like the KEMSO 340LPH reviewed here are a great starting point, providing ample flow for significant power gains and E85 compatibility.

Q3: Can I use an OEM-style replacement fuel pump in my modified Subaru STI?
A3: Generally, no. OEM-style replacement fuel pumps (like the SYKRSS or PHILTOP units) are designed to match the factory specifications of stock, non-performance Subaru models. They lack the high flow rate and pressure capabilities required by a modified Subaru STI and can lead to fuel starvation, inconsistent performance, and potential engine damage. Always opt for a pump specifically rated for high-performance applications.

Q4: Is E85 compatibility important for a Subaru STI fuel pump?
A4: Yes, E85 compatibility is very important if you plan to run ethanol-blended fuels. E85 requires significantly more fuel flow than gasoline, and non-E85 compatible pumps can degrade over time due to ethanol exposure. Pumps like the KEMSO 340LPH are designed to withstand E85, offering longevity and consistent performance when using this high-octane fuel in your Subaru STI.

Q5: What are the main differences between the KEMSO 340LPH and the other fuel pumps reviewed?
A5: The KEMSO 340LPH is a high-performance, aftermarket fuel pump designed for upgraded power levels and E85 compatibility, offering a much higher flow rate and pressure than stock. The other pumps reviewed (Electric Fuel Pump Assembly, SYKRSS, PHILTOP, GPP) are OEM-style replacements meant to restore factory functionality to specific stock Subaru models (Impreza non-STI, Legacy, Outback, Tribeca) and are not suitable for performance Subaru STI applications.

Q6: Where can I find the best fuel pump for my Subaru STI and ensure fitment?
A6: You can find the best fuel pump for your Subaru STI at reputable performance parts retailers like Rally Sport Direct, Subimods, or similar specialized online stores. Always double-check the pump’s specifications against your STI’s year, model, and current modification level. Many manufacturers provide detailed fitment guides. For aftermarket performance pumps, be prepared for potential minor modifications to the fuel pump housing or wiring, though many are designed for relatively straightforward installation.