Virtually every service station in the United States has pumps that feature gasoline blended with 5 percent to 10 percent ethyl alcohol (ethanol). Although highly touted as a renewable alternative fuel, ethanol has caused problems with fuel injectors, especially in older vehicles.
Ethanol has gained popularity and widespread use due to its being a renewable, domestically produced, cleaner burning fuel. It is considered renewable because it is derived from the sugars in corn. The problems ethanol causes to fuel injectors is related to its clean burning attributes.
Because ethanol burns cleaner than gasoline, it will have a cleansing effect on an automobile's fuel system. Over time, gasoline that has little or no ethanol will leave deposits and varnish in the system. Once a higher blend of ethanol is used, the deposits will loosen and the fuel injectors and fuel filters can become clogged. Vehicles manufactured prior to 2000 often have numerous issues with the fuel injection system because there is a greater amount of fuel deposits left behind by non-ethanol gasoline.
If a fuel system becomes clogged due to gasoline deposits, the injector will not be able to supply the proper amount of fuel to air ratio, leading to a sluggish, sputtering motor. The car will need the injector cleaned and fuel filter replaced. However, additional deposits may still be present in the fuel system which will inevitably lead to the same problem. Eventually, the deposits will be flushed and you will no longer have issues. Newer model cars will not have this problem as they will have always been operated on ethanol mixed gasoline.
