A flex-fuel vehicle is designed to run on gasoline or a blend containing up to 85-percent ethanol. While you may convert an engine built to run only on unleaded fuel to run on ethanol, it may be cost prohibitive and extremely difficult.
Start your vehicle conversion by checking with the EPA. You must make sure your car is certified for conversion and that the kit you are using is legal.
Find an E85 conversion kit approved by the EPA that will work with your car. The components that come in a kit can also be purchased separately. Used parts may even save you money.
Run through your car's normal maintenance routine before starting the conversion to flex fuel. The flex-fuel kits work best on cars that are in proper working condition. The number of miles doesn't really matter, but your car should not be hard to start, burn fuel too quickly or have poor compression.
Replace any rubber components with ethanol-quality parts. Most vehicles manufactured after 1990 are rubber-free, but older parts may corrode with ethanol usage. This goes for any ethanol combination, even at low values commonly found in unleaded gasoline.
Examine your fuel pump. If it runs fine at full throttle with regular gasoline, it will probably work with ethanol. However, you may need to modify an older fuel pump to convert you car to flex fuel.
Replace your fuel filters as you initially convert the vehicle. You may see increased sediment buildup the first few months as your engine rids itself of the previous gas traces. Change your fuel filters frequently at first or whenever you run for long periods on high gasoline-content fuel.
Test you oxygen sensor to ensure you can run on high ethanol-content fuel. Older sensors may work fine with combinations up to 50 percent. If your car misfires or has problems at higher combinations, try replacing your sensor.
Follow the directions included with your E85 flex-fuel conversion kit. Deviating form the manufacturer's suggestions may make your car's emission worse than they were before the conversion to flex fuel.
