Sunday, August 21, 2011

Ethenol In Your Fuel

Ethanol Fuel:  This spring and summer (more than any other that I can remember) there have been many sailors at Bayview, Idaho and elsewhere that have experienced engine problems with their outboards.  It happened to me this spring with my six-year old Mercury 8hp – electric start.  I could get the engine started; but, as soon as I’d throttle back so-as to shift into forward or reverse the engine would hardly run and often died.  Finally, I had the engine die as I idled up the slip row toward Snickerdoodle’s slip.  Fortunately, I had enough way on to drift into the slip, jump to the dock, and tie up.  I drove the car over to MacDonald’s Resort and talked with Gary MacDonald.  He suspected that the ethanol in the gas had “gunked” up the carburetor.  I went back to Snickerdoodle and checked the in-line fuel filter in the engine.  Sure enough, it, indeed, had little black flecks of “stuff” in it.  I replaced the filter… but the low speed problems continued.  Finally, I asked Gary to see if his techs could fix the carburetor.  They worked on the engine (blew out the carb) during the following week and the engine did run marginally better… but not as well as it really should.

Meantime, Kathy and I were in Seattle and I went over to Freemont (near Gas Works Park) and visited Fisheries Supply.  At Fisheries I bought a small Racor fuel/water filter (Racor 025RAC02).  This little filter is perfect for small outboard engines.  It has a 10 micron filter (replaceable) and filters both sediment and water out of the fuel.  The filter element is housed in a clear bowl so I can see if there is sediment building up and/or if water is being separated.  I installed the filter in the fuel locker with approximately half of the fuel line on the engine side of the filter and the other half of the fuel line to the fuel tank.  I’m glad that I installed the filter… it’s something that I should have done years ago.  But, the engine still didn’t perform as well as it should at low speed - idle.
I took the engine off Snickerdoodle and brought it in to Spokane Outboard in the Spokane valley.  There the carburetor was taken off the engine and completely disassembled.  The parts were placed in a special “sonic” bath that completely cleans everything of anything.  The carb was then reassembled and installed back on the engine.  The outboard now starts and runs much better - - I haven’t had to drift back into the slip……

I did some research regarding ethanol in gasoline and found some interesting facts.  Here’s a link to the Mercury outboard engine site describing ethanol and its problems.
The problems are numerous:
First, ethanol is a strong solvent that can erode and degrade fuel lines and carburetor components – especially in older engines that were produced before ethanol was being added to gasoline.  Ethanol can also scour any shellac buildup from the inside of the carburetor.  Both conditions can put little bits of “crud” in the jets and plug them partially or completely.  Newer engines are more compatible with this condition than older engines.  But the newer engines still have similar problems over the “long run”.
Second, ethanol is hydroscopic - - it attracts water out of the surrounding air.  The longer the ethanol sits unused, the more water it can put into your fuel.  Of course, water doesn’t burn well in your engine.
Also, if significant amounts of water are present in a fuel tank with gasoline that contains ethanol, the water will be drawn into the fuel until the saturation point is reached for the three-component mixture of water + gasoline + ethanol. Beyond this saturation level of water, phase separation could cause most of the ethanol and water to separate from the gasoline and sink to the bottom of the tank, leaving gasoline with a significantly reduced level of ethanol in the gasoline at the top of the tank. If the quantity of water and ethanol is large enough to reach the fuel inlet, it could be pumped directly to the engine and cause significant problems. Even if the ethanol/water at the bottom of the tank is not drawn into the fuel inlet, the reduced ethanol level of the fuel reduces the octane rating by as much as 3 octane numbers, which could result in engine performance problems.
The level at which phase separation can occur is determined by a number of variables, including the amount of ethanol, the composition of the fuel, the temperature of the environment and the presence of contaminants. It is very important (A) that the system is inspected for significant quantities of water in the tank before using gasoline with ethanol and (B) to limit exposure of the fuel tank to excess water. If phase separation has occurred, it is necessary to completely remove all free water from the system and replace the fuel before continuing operation. Otherwise, engine problems could occur.
Third, ethanol has about 30% less heating value compared to gasoline.  So, the ethanol actually makes the gasoline less effective when it burns in the engine… leading to poorer gas mileage and performance at both the top end and at lower engine speeds.
Forth, most outboard manufacturers state that their engines work with 10% ethanol blended gasoline.  However, all of the manufacturers caution that 15% or 20% ethanol blends should NOT be used in their outboard engines.  The problem is that many states are already mandating that 15% ethanol blends replace 10%.  If you are buying gasoline for your outboard engine at the gas station be aware of the blend.  If there is 15% or more ethanol, don’t buy it for your boat’s engine.  The cheaper price at the “pump” will be a lot more expensive when you see the repair mechanic.
Fifth, all of the manufacturers recommend adding an ethanol stabilizer to every tank of gas.  Some marinas add the stabilizer to their marine gas as a matter of doing business (MacDonald’s Resort at Bayview, Idaho does this)… other’s do not.  I have a bottle of ethanol stabilizer on Snickerdoodle now and use it if I cannot guarantee that the gas is already treated.  It seems that “marginally” too much stabilizer doesn’t have negative results.
Sixth, just about every mechanic recommends unplugging the gas line from the engine and running the engine until the fuel is burned out of the carb.  This is especially so if the engine is to sit for more than a week or two.  Many mechanics also recommend emptying the fuel tank as part of winter layup (put the fuel in your car’s tank), or anytime the engine won’t be used for eight weeks or more.  Start with new gasoline next spring.
This isn’t a pretty picture at all.  But, for those of us with outboard engines, fore-warned is probably fore-armed.


  1. It is a buck a gallon more, but the station at 4th street exit from I-90 x-street Appleway in Coeur d'Alene fills all my lawn equipment, my jet-ski and fuels Spirit's tank. There is a big warning on the pump about the price difference. It is the premium nozzle.

  2. Thanks for the comment. Is that premium gas ethanol free??? Or, ten percent ethanol added to premium???

  3. Bill, as always I enjoy all your blogs and E-mails they are informative an interesting. I just wanted to thank you for your contribution to sailing as I feel we are fortunate have this local knowledge available.

    Thanks again,

    David Sewell
    C-25 owner

  4. I forgot to mention, it is ethanol free, at 93 octane. I found it through a site that tracks ethanol free stations and some are in Spokane too. All are priced about a buck more a gallon.