The instructions for my outboard specifically recommend using only ethanol-free gasoline. Around here I know where I can get it, but I imagine that when cruising it will not always be readily available.
What do you guys recommend doing? Are there particular additives I can use that reduce or mitigate the risks to my outboard posed by ethanol.
I tend to believe the manufacturer's warnings.... but is this an exageration? Is ethanol really a big deal? I have read anecdotal reports on sailnet of significant problems with ethanol.
Interested to learn more. Thanks!
Let me preface this by saying that some of what I'm about to write is based on speculation.
I have an outboard that pre-dates ethanol gas. I started having problems in the last few years. Every time I went to start it, I would have trouble getting it running and keeping it running. If I backed out the idle jet and put it back, the motor would start and run fine---- until the next time. If I repeated the idle jet exercise, I'd be back in business. I had read about how ethanol dissolves the insides of hoses and the the bit clog something, or re-congeal somewhere downstream. This seemed like a reasonable cause and effect in my scenario, so I replaced the hose from the tank to the motor and the hoses inside the motor with hoses rated for ethanol. This seems to have resolved my problem. I've read that on carbureted engines that you need to run them a little richer on ethanol. I don't know if this is true or not, but I backed out the idle jet a little bit and so far, so good.
I've read that in general, condensation alone can't easily cause phase separation, but those vents to prevent it sure can't hurt. I think the main thing is to keep water out of the tanks. To my knowledge, once water gets in and phase separation occurs, nothing will undo it other than emptying and cleaning and emptying and cleaning. For my power boat, I made little covers to go over top of my fill caps to further reduce the chance of water getting in there. Sadly, that boat has sat idle for the last couple of seasons and I've seen no evidence of phase separation with 1/2 full tanks. I empty them before putting the boat up for the winter. There are two schools of thought on this; one says keep them full, the other says empty them. I've chosen to go the route of emptying them, figuring a small mess is better than a big mess.