I have concerns. This is from page 42 of my Optimax Manual:
"We do not recommend the use of gasoline which contains alcohol because of the possible adverse effect they alcohol may have on the fuel system. In general, if only gasoline containing alcohol is availible, it must not contain more than 10% ethanol or 5% methanol, and the addition of a Water Seperating Fuel Filter is recommended.
If gasoline containing alcohol is used or if you suspect the presence of alcohol in your gasoline, increase your inspection of the fuel system, visually check for fuel leaks o abnormalities.
Gasoline containing alcohol may cause the following problems to your outboard and fuel system:
- Corrosion of metal parts
- Deterioration of elastomers and plastic parts
- Wear and damage of internal engine parts
- Starting and operating difficulties
- vapor lock or fuel starvation
Some of these adverse effects are due to the tendency of gasoline containing alcohol to absorb moisture from the air, resulting in a phase of water and alcohol which seperates from the gasoline in the fuel tank.
The adverse effects of alcohol are more severe with methanol and are worse with increasing content of alcohol."
I had heard of these problems as well as the fuel loosing octane if there is any moisture in your fuel system which could cause the motor to shut down. Supposedly the current additive in gasoline causes the gas to float on top of moisture. The ethanol gasoline absorbs moisture.
Called Mercury and spoke to one of the engine techs directly. As long as the engine has the fuel/water seperator installed and filters are replaced regularly, there will be no problem. However, that is up to a mix of 10% of ethanol and 90% of gasoline. If the mixture goes to, say, 15% ethanol 85% gasoline, there could be issues. High concentrations of ethanol could corrode some components. This was demonstrated in the NE last summer with their gasoline mix of 85/15. The rubber and tanks in marine fuel systems were corroding with contaminents going through and clogging the fuel filters and injectors. (Car injectors and fuel system have been designed to run on a mix of 85/15 gas and ethanol). As far as I've been able to find out, Virginia will go to a max mix of 90/10 gas/ethanol this summer, (replacing MTBE), so there should be no problems here. By the way, this has nothing to do with octane rating. You can have 89 octane with a 90/10 mix or a 85/15 mix. Now, with all this talk of 85% ethanol based fuels - all bets are off in the marine world and new fuel systems will have to be designed. GM already has a number of what are called flex fuel vehicles designed to run on a 85% ethanol fuel.
The bad part about that is that the OptiMax cannot have an inline fuel water seperator. My dealer refuses to put another filter (other than what is under the cowling) on my Opti stating that Merc doesnt approve of an inline filter on the engine and the service writer says it causes stalling at low rps due to vaccum issues. Dealer suggests changing the fuel filter under the cowling more frequently.
B-Faithful, yes, I've got 2 of the new 225 Optimaxs and I'm pretty concerned about keeping them in good condition. I also do not have in-line filters. You are right, Mercury states that you should not use in-line filters with the new Optimaxs. The tech told me that the on-board filter will work just fine at stopping water and fuel contamination. We'll probably be changing the filters more often this summer. So,,,watch your fuel, (where you get it from) and ask the station or marina if there is ethanol in the gas before topping off.
[Q]Captain Len Gerylo originally wrote:
By the way, this has nothing to do with octane rating. You can have 89 octane with a 90/10 mix or a 85/15 mix. [/Q]
Durado was asking how do you know whether there is alcohol in the fuel or even that you are getting the octane marked on the pump. He or I were not implying that gas/alcohol mix had anything to do with octane ratings.
ethanol has another big problem. You Burn 2.1 times achohol to gas to produce the same outcome. ethyl burns at a much lower btu. so if you use 10% erthyl then you have to use 2x as much.
if you do the math your range in now only 95% of what it was and you carb if your using an old fassion carb. will be leaner. Now this may not present a problem with you car but a boat motor is under constant load.
The good people at advanced engine design a well known richmond based Carborator specialist sugges the jetting on your carb go up as much as 2 sizes and to "fatten the Mix" thus less fuel range.