Best Fuel Pumps for High HP WRX STI Builds

Alright, fellow Subaru enthusiasts, let’s talk fuel. If you’re anything like me, you’ve spent countless hours under the hood of your WRX STI, chasing that next horsepower goal. Whether you’re upgrading your turbo, running E85, or pushing significant boost, you know that the stock fuel system quickly becomes the weakest link. I’ve been down this road many times, experiencing firsthand the frustration of fuel cuts or lean conditions because my pump just couldn’t keep up. That’s why choosing the best fuel pumps for high HP WRX STI builds isn’t just an upgrade; it’s a necessity for reliability and safety. In this guide, I’ve dug into some popular options, sharing what I’ve learned about their performance, features, and real-world applicability to help you make an informed decision for your power-hungry EJ257. Let’s make sure your high-horsepower beast never starves for fuel again!

IMAGE	PRODUCT NAME	AMAZON LINK
	A-Premium Electric Fuel Pump Module Assembly w/Sending Unit…	View on Amazon
	KEMSO 340LPH High Performance Fuel Pump for Subaru Legacy…	View on Amazon
	QFS-344FT-1008 – Performance 340LPH Fuel Pump Replacement…	View on Amazon
	1 Pcs 8mm Fuel Pump Fuel Line Hand Primer Bulb….	View on Amazon
	KEMSO 340LPH High Performance Fuel Pump for Subaru/Honda…	View on Amazon
	GETOPAUTO 42072AG140 Fuel Pump Filter Compatible With…	View on Amazon
	Subaru NEW 2008-2018 Subaru Fuel Pump Filter Impreza WRX…	View on Amazon

Product Reviews

1. A-Premium Electric Fuel Pump Module Assembly w/Sending Unit

When you’re looking for a direct replacement that maintains OEM functionality while offering solid reliability, this A-Premium assembly often comes up. It’s designed as a complete drop-in unit, which is fantastic for those who want to avoid piecing together components. While it’s primarily an OEM-style replacement for the 2008-2011 WRX STI, it can be a suitable option for mildly upgraded builds or as a dependable stock refresh. You get the fuel pump, the sending unit, and a strainer all in one package, simplifying the installation process considerably. It aims to restore your fuel system to factory specifications, which for some, is exactly what they need before moving to more extreme modifications.

• Vehicle Fitment: Compatible with Subaru Impreza WRX STI 2008-2011, H4 2.5L Gas (Turbocharged, Eng Code: EJ257).
• Reference Number: 42021FG050, FG1915, P76717M, SP4114M.
• Complete Assembly: Includes fuel pump, fuel sending unit, and strainer.
• Warranty: One-year unlimited-mileage guarantee.

Pros:
– Direct drop-in replacement, simplifying installation.
– Comes as a complete module, including the sending unit.
– Cost-effective OEM-style replacement.
– Good for restoring stock fuel system reliability.

Cons:
– May not provide sufficient flow for significantly high HP builds (e.g., 500+ WHP).
– Limited upgrade potential for serious power aspirations.
– Not explicitly designed for E85 compatibility.

Best for: Stock replacements, mild upgrades, or those prioritizing OEM-like reliability and ease of installation over extreme performance for their WRX STI.

User feedback summary: Most users appreciate the ease of installation and the complete package. They find it a reliable OEM alternative that restores fuel pressure effectively. However, several high-HP users note that it’s not a performance pump and quickly becomes a bottleneck beyond stock or minor bolt-on power levels.

2. KEMSO 340LPH High Performance Fuel Pump for Subaru Legacy

Now we’re talking performance! The KEMSO 340LPH pump is a serious contender for high HP WRX STI builds. With a flow rate capable of supporting up to 600 BHP, it’s designed to keep pace with aggressive turbo upgrades and E85 conversions. I appreciate that Kemso builds these pumps with E85 compatibility in mind, which is crucial for many modern high-horsepower builds. The bypass valve set at 125.8psi is also a nice touch, offering higher pressure capability than many standard 255LPH or even some 400LPH pumps. Plus, Kemso offers US-based support and a lifetime warranty, which gives you confidence when investing in such a critical component.

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

Pros:
– High flow rate suitable for significant horsepower gains.
– E85 compatible, essential for many high-performance fuels.
– Robust bypass valve for stable pressure.
– Lifetime warranty offers excellent peace of mind.
– US-based support is a huge plus for assistance.

Cons:
– Requires professional installation for optimal performance and setup.
– Might be overkill for stock or lightly modified vehicles.
– Wiring upgrades might be necessary for consistent power delivery at higher flows.

Best for: High HP WRX STI builds running substantial boost, larger turbos, or E85 fuel, aiming for 450-600+ WHP.

User feedback summary: Owners consistently praise its strong flow capabilities and E85 compatibility, stating it’s a reliable upgrade for forced induction setups. Many highlight the lifetime warranty as a significant factor in their purchase, though some mentioned minor modifications needed for a perfect drop-in fit in certain Subaru models.

3. QFS-344FT-1008 – Performance 340LPH Fuel Pump Replacement

The QFS 340LPH pump is another excellent option in the high-performance category, directly competing with other 340LPH units. Like the Kemso, it’s engineered to support up to 600 bhp, making it a serious upgrade for anyone pushing their WRX STI hard. What stands out here is their emphasis on “peak engineering to guarantee reliability and longevity,” which is exactly what you want when your engine’s life depends on consistent fuel delivery. The promise of a quick and easy drop-in installation, coupled with a vehicle-specific kit, aims to reduce the headaches often associated with performance upgrades. And just like Kemso, QFS backs their product with a lifetime warranty and a dedicated US-based customer service team.

• Supports up to 600 bhp in N/A, turbocharged, and supercharged applications.
• Quick & easy drop-in installation with a vehicle-specific kit.
• Engineered for reliability and longevity.
• Lifetime warranty with dedicated in-house customer service in the USA.

Pros:
– High flow rate supports substantial horsepower.
– Designed for straightforward, direct replacement installation.
– Focus on long-term reliability and durability.
– Lifetime warranty provides confidence in your investment.
– US-based customer service for easy support.

Cons:
– Specific E85 compatibility isn’t explicitly stated in the provided features, though 340LPH pumps often are.
– May require additional wiring upgrades for maximum performance.
– Might still require some tuning adjustments after installation.

Best for: Performance-oriented WRX STI owners seeking a high-flow pump with an emphasis on ease of installation and long-term reliability for up to 600 BHP.

User feedback summary: Users report that the installation is indeed very straightforward for many applications, living up to the “drop-in” claim. They appreciate the consistent fuel pressure and flow under demand. The lifetime warranty and responsive US customer service are frequently mentioned positives, reinforcing trust in the brand.

4. 1 Pcs 8mm Fuel Pump Fuel Line Hand Primer Bulb

Let’s be clear upfront: this 8mm hand primer bulb is not a primary fuel pump for a high HP WRX STI build. While it’s a fuel system component, its purpose is to manually prime a fuel line, typically after running out of fuel or performing maintenance on systems with smaller engines like boats, lawnmowers, or some diesel applications. It’s made of rubber and metal and is useful for quickly getting fuel flowing to a carbureted engine or a small fuel system that lacks a self-priming electric pump. It’s a handy tool to have in a garage, but it won’t power your STI.

• Suitable for most cars (as an accessory), boats, motorcycles.
• Made of durable rubber and metal.
• Dimensions: 15.4 inches in length, 1.8 inches in width, 8mm primer pump.
• Often used for outboard or inboard engines.

Pros:
– Excellent for priming small fuel lines manually.
– Simple, durable construction.
– Versatile for various small engine applications.
– Inexpensive.

Cons:
– Not a fuel pump for a Subaru WRX STI.
– Offers no performance benefit for an automotive fuel system.
– Completely irrelevant for a high HP engine’s primary fuel delivery.

Best for: Priming fuel lines in small engines, boats, motorcycles, or as a general-purpose garage tool. Absolutely not for powering a high HP WRX STI.

User feedback summary: Users find this effective for its intended purpose of priming small engines or draining fuel lines. They appreciate its simple design and durability for occasional use. However, nobody is reviewing this in the context of a high-performance Subaru.

5. KEMSO 340LPH High Performance Fuel Pump for Subaru/Honda

This is essentially the same high-performance KEMSO 340LPH pump as Product #2, but likely listed for a broader range of vehicle applications, including specific Subaru and Honda models. All the strong points remain: it’s a potent upgrade for high-horsepower setups, designed to deliver the fuel needed for turbocharged and supercharged applications up to 600 BHP. Its E85 compatibility is a major advantage for modern performance builds, and the higher bypass valve pressure ensures stable fuel delivery under demanding conditions. The confidence-inspiring lifetime warranty and US-based technical support are also consistent features that make this a very attractive option for serious builders.

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

Pros:
– High flow capacity ideal for significant power increases.
– Fully compatible with E85 fuel.
– Delivers consistent high fuel pressure.
– Strong warranty and reliable customer support.
– Proven performance in various high-HP applications.

Cons:
– Professional installation is recommended.
– May require additional wiring or fuel system modifications.
– Might be more pump than necessary for milder builds.

Best for: Enthusiasts building high HP WRX STIs (or compatible Honda models) that require robust fuel delivery for aggressive tuning, large turbos, and E85.

User feedback summary: Feedback is virtually identical to the other Kemso 340LPH listing, emphasizing reliable high flow, E85 compatibility, and the peace of mind from the lifetime warranty. Many highlight it as a “must-have” upgrade for high-boost applications.

6. GETOPAUTO 42072AG140 Fuel Pump Filter Compatible With

Just to clarify, this GETOPAUTO product is a fuel pump filter, not a fuel pump itself. It’s an absolutely critical component in your WRX STI’s fuel system, especially for high-horsepower builds where clean fuel delivery is paramount. Its job is to prevent contaminants like rust, dust, and other debris from reaching and damaging your fuel pump, injectors, and engine. While it won’t add horsepower, a clogged or failing filter can quickly lead to fuel starvation, reduced performance, and even catastrophic engine damage. This particular filter fits a wide range of Subaru models, including the WRX and STI, ensuring your expensive performance fuel pump and injectors are protected.

• Function: Filters solid impurities from fuel to protect the fuel pump, nozzle, cylinder liner, and piston ring, preventing wear and clogging.
• Fitment: Compatible With 2009-2013 Subaru Forester Turbo; 2008-2011 Subaru Impreza EJ253 non turbo; 2008-2018 Subaru Impreza WRX; 2008-2018 Subaru STI.
• Replaces parts: 23300-20130, 23300-31110, 42052AG890, 42072AG140, 4560116741830.
• Package includes: 1 x 42072AG140 Fuel Pump Filter.
• Note: Aftermarket replacement part.

Pros:
– Essential for protecting the entire fuel system, including high-performance pumps and injectors.
– Wide compatibility with various Subaru models, including WRX STI.
– Cost-effective maintenance item.
– Helps ensure consistent fuel flow by preventing clogs.

Cons:
– It is not a fuel pump; it’s a filter.
– Aftermarket part, though often reliable.
– Regular replacement is still necessary as part of maintenance.

Best for: Ensuring clean fuel delivery and protecting your primary fuel pump and engine components in any WRX STI build, especially those with high-performance fuel pumps.

User feedback summary: Users generally find this to be a functional and cost-effective replacement for their Subaru fuel filter. Many highlight the importance of replacing this component regularly for proper fuel system health, appreciating its direct fitment.

7. Subaru NEW 2008-2018 Subaru Fuel Pump Filter Impreza WRX

Similar to the GETOPAUTO listing, this item is also a fuel pump filter, a crucial, but separate, component from the fuel pump itself. This particular listing appears to be for an OEM or OEM-equivalent filter, specifically for the 42072AG140 part number. Maintaining a clean fuel supply is absolutely vital, particularly when you’re relying on a high-flow fuel pump to feed your high-horsepower WRX STI. A fresh filter ensures that your expensive performance fuel pump isn’t working overtime trying to push through clogged mesh, and your delicate fuel injectors don’t get fouled by debris. This is a maintenance item that should not be overlooked, especially when dealing with the increased demands of a modified engine.

• Fuel Pump Filter: Part number 42072AG140.
• Fitment: 2009-2013 Subaru Forester Turbo, 2008-2011 Subaru Impreza EJ253 non turbo, 2008-2018 Subaru Impreza WRX, 2008-2018 Subaru STI.

Pros:
– Essential for filtering impurities and protecting fuel system components.
– OEM or OEM-equivalent quality for reliable filtration.
– Broad compatibility with various Subaru models.
– Helps maintain optimal fuel flow and pressure.

Cons:
– It is a filter, not a fuel pump for generating flow/pressure.
– Regular replacement adds to maintenance costs.

Best for: Routine maintenance and protection of the fuel system in 2008-2018 WRX and STI models, ensuring longevity of your high-performance fuel pump and injectors.

User feedback summary: Reviews often focus on the ease of replacement and the importance of using a quality filter to maintain fuel system integrity. Users note it’s an exact fit for their specified Subaru models, reinforcing its utility as a maintenance part.

Helpful Comparison Insights

When you’re talking about best fuel pumps for high HP WRX STI builds, it’s crucial to understand that not all “fuel system” components are actual pumps. From the products reviewed, we clearly see three categories: performance fuel pumps, OEM replacement assemblies, and fuel filters/accessories.

For true high HP WRX STI builds, the KEMSO 340LPH and QFS 340LPH pumps are your go-to choices. Both offer a substantial upgrade in fuel flow, supporting up to 600 BHP, and are designed to handle the increased demands of larger turbos and E85 fuel. The Kemso units stand out slightly with their explicit E85 compatibility and higher bypass valve pressure, making them particularly attractive for ethanol-fueled setups. Both brands offer lifetime warranties and US-based support, which provides significant peace of mind. The choice between Kemso and QFS often comes down to brand preference or subtle differences in installation kits, but either will be a substantial improvement over stock. Expect to potentially upgrade your wiring or even your fuel lines to get the most out of these high-flow pumps.

The A-Premium Electric Fuel Pump Module Assembly is a different beast. It’s an excellent OEM-style replacement, perfect for restoring factory performance to a 2008-2011 WRX STI. If your build is only lightly modified (e.g., stage 1 or 2 with basic bolt-ons) and you just need a reliable, easy-to-install pump that includes the sending unit, this is a solid choice. However, for genuinely high HP WRX STI builds pushing beyond 400 WHP, this pump will likely be insufficient and restrict your engine’s potential, leading to lean conditions under heavy load.

Finally, we have the crucial supporting components: the GETOPAUTO and Subaru OEM/Equivalent Fuel Pump Filters, and the 8mm Fuel Line Hand Primer Bulb. The fuel filters (products 6 & 7) are absolutely vital for any build, stock or high HP. They protect your expensive performance fuel pump and injectors from debris. While they don’t provide flow themselves, a clogged filter will starve even the most powerful pump. Always ensure you have a clean, high-quality fuel filter. The hand primer bulb (product 4) is entirely unrelated to a performance WRX STI fuel system; it’s a manual priming tool for smaller, simpler engines and should not be considered for your high-horsepower Subaru build.

In summary, for true high HP, focus on the 340LPH performance pumps. Don’t forget the importance of a clean fuel filter for reliability, and know that not all “fuel pump” listings are what they seem for a performance car!

Final Verdict

When it comes to powering a high HP WRX STI build, your fuel pump isn’t just a part; it’s the heart of your performance system. If you’re serious about pushing big numbers, running E85, or simply ensuring your engine gets every drop of fuel it needs under boost, you must invest in a dedicated high-performance fuel pump.

My top recommendations for best fuel pumps for high HP WRX STI builds are unequivocally the KEMSO 340LPH and QFS 340LPH units. Both offer the necessary flow and pressure for substantial power gains, with the Kemso having a slight edge due to its explicit E85 compatibility and higher bypass valve setting, making it a fantastic choice for ethanol users.

For those simply looking to replace a failed stock pump or to support very mild upgrades, the A-Premium Electric Fuel Pump Module Assembly provides a convenient, direct-fit solution that restores OEM functionality. However, it’s crucial to understand its limitations for extreme horsepower.

And please, remember the unsung heroes: the fuel pump filters. Products like the GETOPAUTO and Subaru OEM/Equivalent filters are non-negotiable. They protect your investment in high-performance fuel pumps and injectors, ensuring your expensive components run smoothly and your engine stays safe. Neglecting a clean filter is a recipe for disaster.

In short: Go big with a 340LPH pump for high HP, keep your filter clean, and always double-check what you’re buying to ensure it’s actually suitable for your build!

FAQ Section

Q1: Why do I need a “performance” fuel pump for my high HP WRX STI build?
A1: The stock fuel pump in your WRX STI is designed to deliver enough fuel for the factory horsepower levels. Once you start adding performance modifications like larger turbos, increased boost, or E85 fuel, your engine demands significantly more fuel. A “performance” fuel pump provides the higher flow rates and consistent pressure needed to meet these demands, preventing dangerous lean conditions that can lead to engine damage. It’s a critical upgrade for reliability and safety when chasing high horsepower.

Q2: What does LPH mean, and why is 340LPH better than 255LPH for high HP WRX STI builds?
A2: LPH stands for Liters Per Hour and indicates the fuel pump’s flow rate. A higher LPH rating means the pump can move more fuel. For high HP WRX STI builds, 340LPH pumps like the KEMSO or QFS provide a substantial increase in fuel delivery compared to common 255LPH upgrades or stock pumps. This extra capacity is essential for engines producing over 400-500 WHP, especially when using E85, which requires about 30-40% more fuel than gasoline.

Q3: Are all these “Best Fuel Pumps for High HP WRX STI Builds” compatible with E85 fuel?
A3: Not necessarily. While many high-performance pumps like the KEMSO 340LPH are explicitly designed and rated for E85, standard OEM-style pumps (like the A-Premium assembly) are typically not. E85 is more corrosive than gasoline and can degrade internal pump components not designed to handle it, leading to premature pump failure. Always check the product specifications for E85 compatibility if you plan to run ethanol.

Q4: Do I need to upgrade other parts of my fuel system when installing a high-performance fuel pump in my WRX STI?
A4: Often, yes. While a new performance fuel pump is a major step, for serious high HP WRX STI builds, you might also need to consider upgrading:
– Fuel Injectors: To match the pump’s flow and accurately deliver fuel.
– Fuel Pressure Regulator (FPR): To maintain stable fuel pressure with higher flow.
– Fuel Lines: Stock lines can sometimes be a restriction or may not be E85 compatible.
– Fuel Pump Wiring: To ensure the pump receives adequate voltage and amperage, preventing voltage drop.
– Fuel Filter: A clean, high-flow filter is always critical, as discussed in the article.

Q5: What’s the difference between a “fuel pump” and a “fuel pump filter” for my WRX STI?
A5: This is a crucial distinction! A fuel pump (like the Kemso or QFS 340LPH) is the active component that draws fuel from the tank and pushes it under pressure to the engine. It’s what creates the flow. A fuel pump filter (like the GETOPAUTO or Subaru filters) is a passive component designed to remove contaminants from the fuel before it reaches the pump and injectors. While the filter is essential for protecting the entire fuel system and ensuring clean fuel delivery, it does not generate flow or pressure itself. Both are vital, but they perform different functions in a high HP WRX STI build.

Q6: Can I install a high-performance fuel pump myself, or should I get professional help?
A6: While some experienced DIYers can tackle a fuel pump installation, it often involves working with flammable fuel, specialized tools, and potentially modifying wiring. For a high HP WRX STI build, ensuring proper installation is critical for safety and performance. I generally recommend professional installation, especially for the actual best fuel pumps for high HP WRX STI builds to ensure everything is done correctly, securely, and that no leaks or electrical issues arise. Post-installation tuning by a professional is also highly recommended to optimize your engine’s performance and safety with the new pump.