Honda engines are designed and certified to run on regular unleaded gasoline.
Gasoline is allowed, by regulation, to contain a variety of additives. The same
regulation limits how much of some additives, such as alcohol, can be included in
the fuel and still be sold as gasoline. If you look in a Honda product
owner’s manual, you will see that a maximum of 10% ethanol is allowed
in gasoline (other oxygenates are also listed). Honda engines are designed for good
performance and efficient operation using gasoline containing from 0 to 10% ethanol.
E85, a mixture of 85% ethanol and 15% gasoline, has been in the news recently. E85 is an alternative fuel; it is not gasoline. Honda Marine engines are not currently designed or certified to run on E85 or any other alternative fuel.
Always refer to your Honda owner’s manual for a list of recommended fuel and the current approved additives.
The length of time that gasoline can be left in your fuel tank and carburetor without causing functional problems will vary depending on a variety of factors.
Other factors include:
Instructions regarding the maintenance and storage of your specific outboard model are contained in the STORAGE section of your Honda owner's manual. This section covers all aspects of storage such as adding fuel stabilizer and draining the fuel tank and carburetor, as well as storage precautions and removal from storage.
In storage, gasoline immediately starts to oxidize and deteriorate. The older it gets the more it deteriorates and the more likely it will cause hard starting, performance issues and gum deposits that clog the fuel system.
If the gasoline in your fuel tank and carburetor has significantly deteriorated during storage, you may need to have the carburetor and other fuel system components serviced or replaced.
The Distributor's Limited Warranty does not cover fuel system damage or engine performance problems resulting from deteriorated fuel.
E85 contains 85% ethanol and must not be used in Honda Marine outboards.
Using fuels with percentages of ethanol or methanol higher than 10% may cause starting and/or performance problems. Such use may also damage metal, rubber, and plastic fuel system components.
Using a fuel with percentages of ethanol or methanol greater than 10% may cause engine damage or performance problems that are not covered under the Distributor’s Limited Warranty.
A gasoline/alcohol tester, tool number 07APJ-001A200, is available to determine the percentage of ethanol in a fuel sample. The tester can be ordered from American Honda Parts Department through your local Honda Marine dealer.