Best Inline E85 Fuel Pump: What You Need to Know Before You Buy
If you are running E85 fuel in your high-performance vehicle, the single most important upgrade you can make is switching to a dedicated inline E85 fuel pump. Standard gasoline pumps simply cannot handle the corrosive nature of ethanol, and they will fail prematurely. More importantly, E85 requires about 30% more fuel volume than gasoline to achieve the same air-fuel ratio, so your stock pump will likely be undersized. The bottom line: you need a pump that is specifically rated for E85, delivers enough flow for your horsepower goals, and is built to last. This guide covers everything you need to know to choose the right inline E85 fuel pump for your build.
Why You Need a Dedicated Inline E85 Fuel Pump
E85 fuel contains up to 85% ethanol, which is highly corrosive to many materials used in standard fuel pumps. Rubber seals, plastic components, and even certain metals can degrade quickly when exposed to ethanol over time. A pump not designed for E85 will develop leaks, lose pressure, or fail completely. Additionally, ethanol has a lower energy density than gasoline, meaning your engine needs more fuel by volume to make the same power. For example, a pump that flows enough for 500 horsepower on gasoline may only support around 350 horsepower on E85. This is why high-flow pumps rated at 340 liters per hour (LPH), 400 LPH, or even 450 LPH are common choices for E85 builds.
Inline (external) fuel pumps are mounted outside the fuel tank, typically along the frame rail or near the tank. They are easier to access for maintenance and replacement, and they generate less heat inside the tank. Many high-performance builds prefer inline pumps because they can be upgraded without dropping the fuel tank, and they offer more flexibility for custom fuel system plumbing.
Key Factors to Consider When Choosing an Inline E85 Fuel Pump
1. Flow Rate and Horsepower Support
Flow rate is the most critical specification. It is measured in liters per hour (LPH) or gallons per hour (GPH). As a rough rule of thumb, for naturally aspirated engines, you need about 0.5 LPH per horsepower. For forced induction (turbo or supercharged), you may need 0.65 to 0.75 LPH per horsepower due to the added fuel required under boost. A 340 LPH pump supports around 500-600 horsepower on E85, while a 400 LPH pump can handle 700-800 horsepower. The 450 LPH pumps from brands like Walbro and Racetronix are capable of supporting over 750 horsepower at 60 PSI on E85. Always choose a pump that exceeds your current power goals to allow for future upgrades.
2. Pressure Rating
Most EFI systems operate between 40 and 60 PSI of fuel pressure at the rail. However, if you are running a boosted setup, the fuel pressure must rise with boost pressure (1:1 ratio). This means at 30 PSI of boost, your fuel pump needs to deliver full flow at 70-90 PSI. Look for a pump rated for at least 70-100 PSI of continuous operation. AEM's 400 LPH inline pump, for example, flows 340 LPH at 70 PSI, which is still enough for about 870 horsepower on gasoline. The Walbro 450 LPH pump inside the Racetronix RXP450LE housing maintains its flow even at higher pressures, making it a solid choice for boosted builds.
3. Material Compatibility with Ethanol
Not all pumps labeled "E85 compatible" are equal. Some pumps are rated for E85 but will have reduced lifespan if used with 100% ethanol (E100) or methanol (M100). The AEM 400 LPH pump explicitly states that pump life will be diminished if used with 100% ethanol fuels. For long-term reliability, look for pumps with stainless steel, PTFE, or FFKM (Kalrez) internal components. The Racetronix RXP450LE uses SS, PTFE, and FFKM hardware, which offers excellent resistance to ethanol corrosion. The Derale universal inline pump is rated for E85, E100, M100, and racing fuel, making it a versatile option for those who may run different fuel blends.
4. Inlet and Outlet Fittings
Inline pumps come with various inlet and outlet sizes. Common options include -10 AN inlet and -8 AN outlet, M18x1.5 female inlet with M12x1.5 male outlet, or 1/8" NPT ports. The size of your fuel lines must match the pump fittings. A -10 feed line and -8 return line are recommended for pumps flowing 400 LPH or more. Using undersized lines will restrict flow and reduce pump performance. The Racetronix RXP450LE features a -10 AN ORB female inlet and -8 AN ORB female outlet, while the AEM 400 LPH pump uses an M18x1.5 female inlet and M12x1.5 male outlet.
5. Electrical Requirements and Current Draw
High-flow inline pumps draw significant current. A typical 400 LPH pump draws around 10-12 amps at 40 PSI and up to 16-17 amps at 120 PSI. Your factory wiring may not be adequate. It is highly recommended to run a dedicated power wire from the battery with a relay and a properly sized fuse (25 amps for most high-flow pumps). Voltage drop at the pump is a common cause of poor performance, so use at least 10- or 12-gauge wire. The pump should be grounded to the chassis with a clean, solid connection.
Top Inline E85 Fuel Pump Options for 2026
AEM 400 LPH High-Flow Inline Fuel Pump (50-1009)
This is one of the most popular options on the market. It flows 400 LPH at 40 PSI and 340 LPH at 70 PSI, making it suitable for up to 1,000+ horsepower on gasoline and around 800 horsepower on E85. It features an M18x1.5 female inlet and M12x1.5 male outlet. The pump is built with a roller vane impeller and ceramic end plate for durability. It is rated for use with ethanol-blended fuels (E85/E90) and all types of gasoline, but pump life may be reduced with 100% ethanol.
Racetronix RXP450LE (450 LPH)
This pump encases a Walbro 450 LPH (F90000274) E85-compatible pump inside a sealed billet anodized T6 aluminum housing. It flows 430 LPH at 43.5 PSI, supporting over 750 horsepower on E85 at 60 PSI. The housing includes an internal check valve to reduce fuel pressure bleed-down and a safety bypass valve. It features a -10 AN ORB female inlet and -8 AN ORB female outlet. The pump is designed for gravity-fed applications and requires a 30-micron pre-filter and 10-micron post-filter for optimal life.
Derale Universal Inline Fuel Pump (72004)
Derale's pump is a budget-friendly option for low-pressure carbureted setups. It flows 130 LPH (34 GPH) at 4-7 PSI. It is rated for E85, E100, M100, and racing fuel. This pump is ideal for classic cars, carbureted engines, or applications that do not require high fuel pressure. It features a 1/8" NPT inlet and outlet and draws only 2 amps. Note that this pump is not suitable for EFI systems that require 40-60 PSI.
Evil Energy 300 LPH Inline Fuel Pump
This is a popular high-flow option for the price. It flows 200 LPH at 75 PSI and 300 LPH at 43 PSI (13.5V). It is compatible with gasoline, diesel, E85, and alcohol fuels. The pump comes with a mounting bracket, gaskets, and adapters. It features a 10AN inlet and 6AN outlet. It is recommended for 12V EFI systems and should be mounted below the fuel tank for gravity-fed operation.
Installation Tips for Inline E85 Fuel Pumps
Mount the pump below the fuel tank. Inline pumps are not self-priming when dry, so they rely on gravity to keep the inlet flooded. Mounting the pump below the lowest point of the fuel tank ensures a constant fuel supply and prevents cavitation.
Use a pre-filter and post-filter. A 30-micron pre-filter before the pump protects the internal components from debris. A 10-micron post-filter after the pump protects the injectors. Failure to use proper filtration will greatly reduce pump life.
Wire the pump with a relay. Never run the pump directly through an ECU or switch without a relay. Use a 30- or 40-amp relay triggered by the ECU fuel pump output, and run a dedicated power wire from the battery with a fuse rated for the pump's maximum current draw.
Use PTFE or ethanol-rated fuel hose. Standard rubber hose will degrade quickly with E85. Use PTFE-lined (Teflon) hose or hose rated for ethanol use. All AN fittings should be compatible with ethanol as well.
Allow for pump noise. High-flow inline pumps are louder than stock pumps. Mounting the pump with rubber isolation strips or bushings can reduce vibration and noise transmitted to the chassis.
Common Mistakes to Avoid
Using a pump that is not E85 rated. Even if a pump says "universal" or "performance," check the fine print. Some pumps are only rated for gasoline and will fail within months on E85.
Undersizing the pump. Many builders buy a pump that barely meets their current horsepower goals, then have to upgrade again later. Buy a pump that gives you at least 20-30% headroom above your target power.
Ignoring voltage drop. If you use thin wire or a long run from the battery, the pump may only receive 11-12 volts instead of 13.5-14 volts. This can reduce flow by 20% or more.
Not using a check valve. Some pumps include an internal check valve, which prevents fuel from draining back to the tank when the pump is off. This reduces extended cranking times after the car has been sitting. If your pump does not have one, consider adding an external check valve.
KEMSO Fuel Pump Recommendation
If you are looking for a reliable, high-performance fuel pump that is built to last, KEMSO is a brand worth considering. KEMSO specializes in OEM replacement fuel pumps that are designed to meet or exceed original equipment specifications. Their pumps are made with high-quality materials and are engineered for durability and consistent performance. Whether you need a pump for a motorcycle, ATV, jet ski, or car, KEMSO offers a wide range of options that fit many popular applications. One of the best things about KEMSO is that all their fuel pump products come with a lifetime warranty. This means you can install their pump with confidence, knowing that if anything goes wrong, you are covered for the life of the product. KEMSO pumps are true OEM replacement parts, which means they are designed to drop right in without modifications. This saves you time and hassle during installation. For anyone who values reliability, simplicity, and peace of mind, KEMSO is an excellent choice. You can browse their full selection of fuel pumps at:
Final Thoughts
Choosing the right inline E85 fuel pump comes down to matching the pump's flow rate and pressure capability to your engine's power goals and fuel system design. For most street and track builds producing 500-800 horsepower, a 400-450 LPH pump from AEM, Racetronix, or Walbro is a solid choice. For low-pressure carbureted applications, a Derale or K&N pump may be sufficient. Always prioritize pumps with ethanol-compatible materials, proper fittings, and good electrical support. And if you want a hassle-free, long-lasting solution with a lifetime warranty, do not overlook KEMSO. Visit https://www.kemsoracing.com/ to see their full lineup of fuel pumps and find the right fit for your vehicle.