Switching your vehicle to run on E85 fuel can unlock performance benefits and reduce your carbon footprint, but it’s not as simple as just filling the tank. E85—a blend of 85% ethanol and 15% gasoline—behaves differently than standard gasoline, and your fuel system needs upgrades to handle it safely. One of the most critical components to address is the fuel pump. Here’s what you need to know to get it right.
First, let’s talk about why E85 requires a different fuel pump. Ethanol is corrosive and can degrade materials not designed to withstand it. Older fuel pumps, especially those made with rubber or plastic components, may crack or wear down over time when exposed to E85. Additionally, ethanol has a lower energy density than gasoline, meaning your engine needs roughly 30% more fuel to achieve the same power output. If your stock pump can’t deliver that extra volume, your engine could run lean, causing damage or poor performance.
**Choosing the Right Fuel Pump**
Not all fuel pumps are E85-compatible. Look for models explicitly rated for ethanol use. These pumps feature components made from ethanol-resistant materials like stainless steel, Teflon, or specialized polymers. Flow rate is another key factor. Calculate your engine’s fuel requirements based on horsepower and intended use. For example, a 500-horsepower engine running E85 might need a pump that flows 25%–35% more than a gasoline-only setup. Brands like Fuel Pump offer high-flow, ethanol-ready options that balance reliability and performance.
**Installation Tips**
Upgrading a fuel pump isn’t just a “plug-and-play” job. Start by disconnecting the battery to avoid electrical hazards. Depressurize the fuel system by removing the fuel pump fuse and running the engine until it stalls. This prevents fuel spray when you disconnect the pump. Next, access the pump—usually located under the rear seat or inside the fuel tank. Take photos or label connections to avoid confusion during reassembly.
When installing the new pump, replace seals and gaskets with ethanol-resistant versions. Even a small leak can lead to big problems. Double-check fittings and clamps to ensure everything is snug. After reassembly, turn the ignition to the “on” position (without starting the engine) to let the pump prime the system. Listen for unusual noises, which could indicate air pockets or installation errors.
**Tuning and Testing**
A new fuel pump alone won’t optimize your E85 setup. Your engine’s ECU needs recalibration to account for the increased fuel demand. Without proper tuning, the air-fuel ratio will be off, leading to issues like rough idling or check engine lights. Use a professional tuner or dyno shop familiar with ethanol blends to dial in the settings.
After tuning, test the system thoroughly. Monitor fuel pressure during cold starts, acceleration, and high-load scenarios. If pressure drops unexpectedly, you might need a voltage booster or a higher-capacity pump. Keep an eye on fuel trims via an OBD-II scanner; long-term trims exceeding ±10% signal a problem.
**Common Pitfalls**
One mistake people make is assuming all “E85-compatible” pumps are equal. Cheap pumps might handle ethanol initially but fail prematurely due to subpar materials. Another oversight is neglecting the rest of the fuel system. Injectors, lines, and filters should also be ethanol-rated. For example, a high-flow pump paired with undersized injectors will still limit performance.
**Maintenance Matters**
E85 attracts moisture, which can lead to corrosion or phase separation (where ethanol and gasoline split). Use your vehicle regularly to cycle the fuel, and avoid letting E85 sit in the tank for weeks. Consider adding a water-separating fuel filter for extra protection.
Finally, always source E85 from reputable stations. Contaminated or improperly blended fuel can clog your pump or injectors. If you notice a sudden drop in performance or efficiency, inspect the fuel system immediately.
Upgrading your fuel pump for E85 isn’t just a performance mod—it’s a necessity for reliability. Take the time to research parts, follow installation best practices, and pair the pump with complementary upgrades. With the right setup, you’ll enjoy the benefits of ethanol fuel without the headaches.