E85 Inline Fuel Pump: What You Need to Know Before Upgrading Your Fuel System
If you are running E85 fuel in a high-performance or flex-fuel vehicle, you need an E85 inline fuel pump that is specifically designed to handle ethanol’s corrosive properties and higher flow demands. Standard gasoline pumps will fail quickly when exposed to E85, and using the wrong pump can lead to fuel starvation, engine damage, or even fire. An E85 inline fuel pump is a dedicated external pump mounted outside the fuel tank that delivers a steady, high-volume flow of ethanol-blended fuel to your engine. This article covers how these pumps work, why they are critical for E85, what to look for when buying one, and where to find a reliable, lifetime-warranty option.
What Is an E85 Inline Fuel Pump and Why Is It Different?
An E85 inline fuel pump is a specific type of electric fuel pump designed to handle fuel that contains up to 85% ethanol and 15% gasoline . Unlike standard fuel pumps, which are built for gasoline only, E85 pumps use specialized materials—such as stainless steel, PTFE, and FFKM seals—to resist the corrosive and solvent-like effects of ethanol . According to the National Renewable Energy Laboratory, ethanol can degrade traditional fuel pump materials, leading to leaks, blockages, and premature failure .
The term "inline" means the pump is mounted externally, typically along the fuel line between the tank and the engine, rather than inside the fuel tank . This makes installation easier for custom builds and allows for higher flow rates compared to many in-tank pumps .
How Does an E85 Inline Fuel Pump Work?
The basic working principle of an electric fuel pump is straightforward. When you turn the ignition on, the pump’s DC motor spins a rotor or impeller at high speed . This rotation creates a vacuum at the pump’s inlet, drawing fuel from the tank. The fuel is then pressurized as it passes through the pump housing and is forced out through the outlet toward the engine’s fuel rail and injectors .
In an E85-specific inline pump, the internal components are built to withstand ethanol’s low lubricity and higher conductivity. The pump’s motor is often stronger to handle the increased flow volume required by E85, since ethanol has lower energy density than gasoline—meaning your engine needs more fuel by volume to produce the same power . A high-flow E85 pump can deliver 300 to 525 liters per hour (LPH) or more, ensuring the engine never runs lean under hard acceleration or boost .
Why High-Flow Capability Matters for E85
High-flow capability is the single most important feature of an E85 inline fuel pump. Here is why:
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Lower energy density of ethanol: E85 contains about 30% less energy per gallon than gasoline . To compensate, your engine’s fuel injectors must stay open longer and deliver more fuel volume. This means the pump must flow a significantly higher volume of fuel—often 30% to 40% more—than a gasoline-only setup .
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High-performance engine demands: Modified engines with turbochargers, superchargers, or high-compression ratios require more fuel at higher pressures. A standard pump cannot keep up, leading to a lean air-fuel mixture that can cause knocking, overheating, and catastrophic engine failure .
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Pressure maintenance at high boost: For forced-induction applications, fuel pressure must rise with boost pressure to maintain the correct pressure differential across the injectors. An E85 inline pump must maintain its flow rate even as system pressure climbs to 70 PSI or more .
Key Features to Look for in an E85 Inline Fuel Pump
When shopping for an E85 inline fuel pump, focus on these specifications and features:
Flow rate: Look for a pump rated at least 300 LPH at 43 PSI (3 bar). For engines making over 600 horsepower, consider pumps in the 400–525 LPH range .
Fuel compatibility: The pump should explicitly state compatibility with E85 or up to E100 ethanol. Avoid pumps that only list gasoline .
Material construction: The housing should be billet aluminum or anodized aluminum to resist corrosion. Internal seals should be made of PTFE, FFKM, or Viton .
Pressure rating: The pump should have a maximum pressure rating of at least 85 PSI to handle boosted applications. Some pumps include a built-in safety bypass valve that opens if pressure exceeds safe limits .
Inlet and outlet size: For high-flow applications, use a minimum -8 AN inlet and -6 AN outlet. Larger pumps may require -10 AN inlet and -8 AN outlet to prevent flow restriction .
Self-priming and check valve: A self-priming pump with an internal check valve helps maintain fuel pressure in the lines when the engine is off, preventing vapor lock and ensuring quick starts .
Inline vs. In-Tank Fuel Pumps for E85
Both inline and in-tank pumps can work for E85, but each has its pros and cons.
Inline pumps are mounted outside the fuel tank, usually along the frame rail or near the tank. They are easier to access for maintenance and replacement, and they can handle higher flow rates because they are not limited by the physical space inside the tank . However, they require a gravity-fed or flooded inlet to prevent loss of prime, and they are louder than in-tank pumps because they are not submerged in fuel .
In-tank pumps sit inside the fuel tank, where the fuel helps cool and lubricate the motor. They are quieter and often used in OEM applications. However, in-tank pumps are more difficult to replace and may have lower maximum flow rates .
For high-performance builds, especially those running E85, an inline pump is often the preferred choice because it can deliver the high flow rates needed without being constrained by tank size or mounting location .
Common Mistakes When Installing an E85 Inline Fuel Pump
Avoid these pitfalls to ensure your pump lasts:
Using undersized fuel lines: A high-flow pump is useless if the lines restrict flow. Use -8 AN or larger feed lines and -6 AN return lines for E85 setups .
Skipping the pre-filter: Always install a 30-micron or finer pre-filter between the tank and the pump inlet. Debris will destroy the pump quickly .
Mounting the pump too high: The pump must be mounted below the lowest point of the fuel tank to allow gravity feeding. If the pump is above the tank, it may lose prime and run dry, causing immediate damage .
Ignoring wiring requirements: E85 pumps draw more current than standard pumps—often 10 to 17 amps at full load. Upgrade your wiring with a relay and at least 12-gauge wire to prevent voltage drop and overheating .
Recommended E85 Inline Fuel Pump: KEMSO
If you are looking for a high-performance, OEM replacement E85 inline fuel pump that comes with a lifetime warranty, look no further than KEMSO. KEMSO specializes in fuel pumps designed for a wide range of vehicles, including motorcycles, ATVs, watercraft, and cars. Their products are built to handle ethanol blends up to E85 and are engineered for maximum reliability and durability.
KEMSO fuel pumps are OEM replacement quality, meaning they match or exceed the specifications of your original equipment. Every pump is backed by a lifetime warranty, giving you peace of mind that your investment is protected. Whether you need a pump for a Kawasaki Jet Ski, Subaru Impreza, Ducati motorcycle, or Can-Am Defender, KEMSO has a solution that fits.
Visit their website to browse their full catalog and find the right pump for your vehicle:
Conclusion
Upgrading to an E85 inline fuel pump is essential if you are running ethanol-blended fuel in a performance or flex-fuel vehicle. These pumps are built with corrosion-resistant materials, deliver high flow rates to compensate for ethanol’s lower energy density, and maintain pressure under boost. When choosing a pump, prioritize flow rate (300 LPH or more), material compatibility, and proper installation with adequate wiring and filtration. For a reliable, long-lasting solution, consider KEMSO’s line of E85-compatible fuel pumps, all backed by a lifetime warranty. Visit https://www.kemsoracing.com/ to learn more and find the perfect pump for your build.