The chemical concoctions that create ethanol are a problem for fuel pumps because, over time, this can erode and corrode parts. It hates water as ethanol is hygroscopic. This trait has a tendency to trap water in the fuel system, leading rust and corrosion of metal parts inside of both the pump itself as well as any hard lines. Industry studies show fuel systems that use ethanol-blended fuels like E10 and increasing amounts of the more potent E85 suffer 25% higher corrosion-related problems, especially when vehicles remain parked for long periods.
Ethanol's solvent properties also wreak havoc with fuel pumps, which come packed full of rubber gaskets and other non-metallic parts prevalent throughout the feed system. Fuel pumps that see higher ethanol concentrations have fuel pumps with a greater probability of premature failure on seals/gaskets/fuel lines. For instance, natural rubber seals degrade 40% faster when exposed to E10 fuel than they do with non-ethanol gasoline and may leak the solvent or reduce your gas mileage as a result. Ethanol-compatible fuel pumps use elastomers, such as plasticized polyvinyl chloride or fluorocarbon rubber to withstand the solvent action of ethanol.
The efficiency of the fuel pump is further compromised by high ethanol content. Ethanol contains less energy per gallon than gasoline—roughly 33% less—in turn, requiring fuel pumps to work harder in order to pump enough ethanol-based fuel via the lines and into your engine. In high-performance vehicles, or under spirited driving conditions, this demand can cause overheating and stress. These numbers, supplied to us by fuel system manufacturers are based on performance data showing that fuel pumps working with ethanol-rich blends face as much as 15% more wear due to increased operation load and may have a life expectancy of up to 20%.
The ethanol the adsorbent contains increases both water separation and phase separation risks. If the ethanol-blended fuel absorbs too much water, a layer can form at the bottom of the tank that is made up primarily of water and alcohol. By phase separating, the fuel pump can suck up this water-ethanol mix into the motor causing stalling or underperformance from going lean. Automotive experts warn not to keep ethanol-fortified fuel in the system for too long, which would prevent phase separation and help preserve a healthy pump.
An ethanol-compatible Fuel Pump designed with resistant materials and greater quality of life is one way to solve this. Proper pump selection will help the fuel system last much longer and alleviate maintenance from ethanol-induced wear, allowing for reliable performance of all vehicles using ethanol-blended fuels.