Ethanol Free Gasoline

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Tony B

Guru
Joined
Jul 18, 2011
Messages
1,251
Location
Cruising/Live-Aboard USA
Vessel Name
Serenity
Vessel Make
Mainship 36 Dual Cabin -1986
Is there a difference in older gasoline engines (1986) whether I use ethanol free gas or the regular stuff.
I'm sure this has been covered before but I'll ask it again for the latest info.

Thanks in advance.
 
Most thirty year old fuel systems will suffer the ill effects of E10 or higher due to rubber parts softening up and losing sealing or metering ability. FRP tanks from that era are also prone to deterioration and flaking thus plugging fuel systems. I'm sure there are plenty of true life stories to come forward, I'm lucky in that my gas outboard engine gets fuel in Canada where E fuels are less common.
 
, I'm lucky in that my gas outboard engine gets fuel in Canada where E fuels are less common.

Several of the gas stations in my area (Northern Florida) have a pump for "marine gas" (no ethanol), so I use that for my dinghy outboard and the Yamaha 2000 generator/inverter. Might not be necessary, but can't hurt.
 
I know something about this from my experience with automotive engines.

The issue isn't so much the engine itself, which really doesn't care what fuel it burns as long as the fuel has a burn characteristic that is within the engines design parameters. (Compression ration, maximum cylinder pressure, timing, ignition system, etc.)

The issue arises from the fact that unless the entire fuel system was engineered for alcohol, it will tear it up. Older fiberglass tanks, non-synthetic hoses, gaskets/O-rings/sealants in carburetors and fuel injectors... all subject to being destroyed by alcohol.

I have been given to understand that in applications where your fuel sits in your tank for an extended period of time you could run into issues like phase separation and should therefore use fuel stablizers, but then again, you should be using fuel stabilizers in that situation anyway.

Typically, engines and fuel systems built in the last decade can be reasonably presumed to be able to tolerate up to 10% ethanol content, but personally, I would check the owner's manual first. If that wasn't available I would call the manufacturer.


One last thing...
Alcohol is very fond of water. In a high humidity environment it will suck it right out of the air. For this reason alone I personally like to use marine fuel in my boat, not automotive fuel. And that's coming from someone who actually LIKES alcohol fuel. (E85 can be a hot rodder's best friend.)
 
The real problem is I know of no additive that prevents phase separation...there are claims by manufacturers but have never seen a 3rd party study to say what additives can prevent it.

Those that say they use additives and have no problems rank right up there with.... I don't have skin cancer because I drink beer....and it has worked my whole life of 60 years.

Marine gasoline in much of the Northeast does contain up to 10% ethanol as of several years ago...as long as you burn off your fuel every few months..it has never been a big deal with inboard engines...the biggest problem I saw towing vessels was Yamaha outboards for the first couple years it was used. However...if you get any free water in your fuel beyond normal atmospheric humidity...you stand a good chance of phase separation.
 

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