Frank Sargeant writes that boaters should double check the gas pump before filling up the outboard motors tanks.
A proposal to allow 15 percent ethanol mixes in pump gas would be not good for the motors. Actually, the the exact phrase was “poison to current outboards.”
How bad is E-15? Very bad based on tests concluded in 2011 by Mercury Marine for the U.S. Department of Energy. Two of three outboards run on E-15 in Merc’s standard 300-hour, full-throttle endurance test failed to complete the run and showed severe internal damage according to David Hilbert, thermodynamic development engineer for Mercury.
A 300-horse Verado experienced three damaged exhaust valves near the end of the E-15 run, a result which Hilbert says likely came from operating temperatures considerably higher than a similar engine run in the same test on gasoline without any alcohol.
And a 200-horse 2.5 EFI two-stroke in the test had to be shut down after 256 hours due to bearing failure. Hilbert said more testing would be required to determine if the ethanol in the fuel caused a reduction in effective lubrication and brought on the failure, but an identical engine run on standard gasoline had no similar issues throughout the 300-hour WOT run.
So when E-15 arrives at our pumps, we are all going to have to avoid the stuff like ebola-and that can be a bit tricky if the stuff is everywhere, as E-10 is now, and especially if no-ethanol gas and E-10 become hard to find.
And in fact even E-10 is not all that good for marine engines. Where things get a little sticky with E-10, literally, is when old fuel is used, when fuel remains in your boat tanks for months, or when the mix of ethanol exceeds 10 percent, as tests have occasionally shown it does at some service stations.
If an older rig with a fiberglass tank or certain types of rubber or plastic hoses is fueled with E-10, the alcohol may cause damage to some of these components, and alcohol is a great solvent–it literally dissolves the build-up on interior fuel system surfaces, and this stuff can sometimes cause issues with a motor that would not have any problem whatever with the alcohol feeding through a clean, new fuel system.
Honda has advised their dealers that dissolved material can clog the in-line fuel filter and also create deposits on injectors, pumps, pressure regulators, carb jets, valves and other engine parts. While none of this may cause an engine failure, they can all result in degrading performance.
Mercury advises owners that fresh, clean E-10 from a clean fuel system is fine for all motors built in the last 15 years, at minimum. And Yamaha also says E-10 should cause no harm to their motors, though they do advise adding a 10-micron filter to your fuel line to help get rid of sludge or water that may occur in ethanol blend fuels.
Alcohol-blend fuels attract and retain water. If you leave your boat setting outside through most of the winter, the frequent heating and cooling of the air space inside the tank results in condensation, which can build up. It might cause a steel tank to rust, and if the motor starts picking up separated water, it might cause rust problems inside the cylinders, dilution of the oil bathing the rings, and misfiring, among other issues.
What are the hints that your motor may be getting a bad diet? The first warning is an engine that stalls or misses badly when you try to accelerate. Stumbling at idle or trolling speed can also be a hint. Fuel filters that clog frequently are another sign that you have contaminated fuel that could be the result of excess alcohol, or of varnish-like materials dissolved from your fuel tank or hoses by that alcohol.
How do you protect your motor?
1. Buy your fuel at high-volume stations where there’s frequent turn-over; this is likely to avoid build up of condensation in the storage tanks.
2. Avoid storing your boat with a near-empty tank. The less gasoline there is inside, the more space there is for condensation.
3. Avoid running your boat down to near empty; the pickup line is more likely to suck in water or gunk washed off the tank walls when the tank is near empty.
4. Install an extra water-separating fuel filter in your fuel line.