Ethanol

I have a 2005 70 HP Yamaha and was wondering what effects Ethanol may be having. I was at the local dealer yesterday getting a few basic things to service the motor and they said Yamaha is recommending fuel filter/separator replacement every 20 hours now. Another thing I was wondering, wouldn't the amount of fuel going through my standard cartridge filter vary greatly between small and larger outboards? That's a lot of filters, where does the 20-hour rule fit in?

[boats.net]

10% or less Ethanol is ok. Ethanol attracts moisture and thats why the fuel/water filter needs to replaced. Yamaha has 2 different size filters up to 115hp and larger filter for above 115hp.

10% Ethanol

For two years now I have been using, at Yamaha's instruction, a fuel enzyme, in addition to StaBil for my Yammie 60. The enzyme is StarTron, made by StarBrite and available at Boater's World. It requires only a 1/3 oz per 5 gal, so a bottle goes a long way. I store my boat for 3 months in the winter with StaBil and StarTron in the 21 gal tank filled and so far no problems. The Yamaha rep did also advise a fuel/water separator, but I have not put one on yet.
StaBil now has a product made specifically for the 10% ethanol mix.
The StarTron enzym seems to be doing the trick added each time I add gas.

[MrPat]

Stabil, at least the red fluid, is a form of alcohol. Adding alcohol to alcohol won't do much good

[TinBoatTom]

Yamaha 'Ring Free'

I have a F9.9 and was told by the dealer to use Yamaha 'Ring Free' according to the directions on the bottle: 1 oz. per 10 gal.
OK for us small guys, but would be expensive for you high HP guys.

Ring Free Is A Must - Fuel Water Separator is Also

The ethanol not only causes large build ups of water in your fuel tank but it also destroys your fuel system hoses if they are not specifically the type designed to handle ethanol. I have replaced my entire fuel system from the tank to the injectors with ethanol designed fuel hoses. I have also added a 10 micron Yamaha fuel-water separator/filter. The best bet is to avoid using ethanol if you can find the ethanol free fuel. We have only 2 stations in my county that have it. With any Yamaha 4-stroke you must use the ring free or you’re going to pay big buck for repairs. The ring free prevents carbon build up on the piston rings which would cause reduced combustion pressure. Carbon also would build up extremely fast on your valves without it.

[robert graham]

I use the Walmart fuel/water seperator, Ringfree and Stabil Marine all the time. I just unscrew the cartridge, dump it onto a clean rag or clean container to check what's in it, re-install cartridge and pump it back full with primer bulb. I also continue to check fuel filter on motor to be sure nothing sneaks past my fuel/water seperator. Drain carbs several times per year to be certain they're clean and free of contaminates. I do carry a spare cartridge in my boat, but so far there's very little of anything in the system. When I do change the cartridge I'll cut open the old one with a hack saw to see what's in it. The Walmart cartridges are $7 and the Yamaha ones must cost quite a bit for a 20 hour change. All this depends on your boat, motor, size and construction of your fuel tanks, etc. Good Luck!