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5th April 2013
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23rd April 2013
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Ethanol Fuel Issues

Dear Customer

G & G Marina has recently received several inquires about the state mandate to add 10% Ethanol alcohol to gasoline sold in Missouri. Ethanol is a highly refined alcohol produced from natural products such as corn, sugar cane and wheat. New technology will allow Ethanol to be made from corn stalks, grain straw, paper, pulp, wood ships, municipal waste, switch grass, and other sources. Ethanol can create operating issues with marine engines. Listed below are some of the problems and recommendations to prevent these problems from interrupting your boating season.


Alcohol attracts and absorbs moisture from the air. Marine fuel tanks are vented to air meaning a more likely chance to having moisture in your fuel system. Alcohol more readily blends with water than gasoline. Phase separation occurs when alcohol in gasoline falls out of suspension and drifts to bottom of fuel tank. Phase separation occurs quicker with the aide of moisture, and we all know how humid Missouri can be in the summer. Phase separation increases the chance of your engine ingesting a blend of alcohol and water during start-up after a prolonged period of storage. This can happen in as little as 2 to 4 weeks. Basic math says that if we have 100 gallons of gasoline with 10% Ethanol in our fuel tank, after phase separation we now have 10 gallons of alcohol and water in the bottom of our fuel tank where the fuel pick-up for the engine is located.

Alcohol can dissolve some solid materials in the fuel system. Alcohol can loosen corrosion and varnish in the fuel system, contaminating the fuel, plugging fuel filters, and damaging fuel injectors and carburetors. Alcohol can dissolve rubber fuel system components, fiberglass fuel tanks, and cause corrosion in aluminum fuel tanks.

Alcohol blended fuels can cause vapor lock issues in marine engines. Vapor lock is the point when liquid fuel turns to vapor. Chances of vapor lock increase with the amount of alcohol in gasoline, engine operating temperature, and ambient air temperature. When engine is shut down temperature in fuel system increases turning liquid gasoline to vapor making it hard for the fuel pump to deliver fuel to the injectors or carburetor.


Ask questions about the amount of Ethanol in the fuel you are purchasing. Gasoline sold by G & G Marina will NOT contain Ethanol. Also our fuel has Valvtect added. Valvtect contains Valvtect Octane Performance Improver, combustion modifier, gasoline detergent, fuel stabilizer, and an anti-wear additive. Valvtect improves combustion, increases octane performance, stabilizes fuel, and extends engine life. It is important for you to know the gasoline you are using and informing us so we can properly maintain and winterize your boat. If you are using an Ethanol blended fuel you should store your boat with an empty fuel tank. If you use non-ethanol blended fuel, store your boat with a full fuel tank.

Replace water separator and fuel filters on a regular basis. G & G Marina replaces water separator filters when we perform a complete winterize. We replace all fuel filters when we perform a complete tune-up. If your boat is not equipped with a water separating fuel filter we recommend having one installed.

Replace water pump impellers on a regular basis. Proper operation of cooling system will help prevent vapor lock. Engine compartments have grown smaller with more sound proofing up through the years. This has led to less air flow in compartment and higher air temperatures. Operating bilge blower while idling and for 5 minutes after shut down will lower this temperature.

In closing, Knowledge is power. The more you know about the gasoline you are using and the maintenance performed on your boat, the better you will be protected. Most fuel tanks and marine engines manufactured in the last 10 years are alcohol resistant, but not alcohol proof. G & G Marina staff will be happy to answer any questions you may have.
Information gathered from service bulletins provided by the following manufacturers:
Honda Marine Mercruiser Volvo Penta Bombardier Valvtect