When the ethanol fuel came on the market, people started to experience problems that had never occurrred previously. My uncle had a couple of muscle cars that needed new accelerator pump diaphragms every spring after storage, and as forum member ZAR can probably tell you the fuel pump diaphragms in Briggs and Stratton engines were becoming soft and deformed - while the normal failure mode used to be the diaphagms would get holes in them or dry out and get stiff. I have several pieces of equipment that had fuel hoses that dissolved and became like sticky taffy. My neighbors started bringing their yard equipment over to me far more than they used to......as they could not get them started in the spring. My own experience has been that equipment that is stored in an insulated and heated garage or basement stores much better than equipment that is stored outdoors, under a carport, or in a barn where the temperature and weather conditions swing wildly.
In an effort to satisfy my curiousity, I filled some plastic bottles with different fuels to see what changes I could see in the fuel. I filled each bottle to the same level and set them on a shelf in my garage. I did not take a picture when I bottled them up two year ago.......but this is what the bottles look like after two years of storage. The first bottle on the left is pump gas regular with 10% ethanol, the second bottle is Sunoco 96 octane racing fuel, the third bottle is Avgas 100LL, and the fourth bottle is CountryMark 90+ fuel that has no ethanol. The bottles were all filled to the horizontal molding line in the middle of the bottles where the first and third bottle levels are, and the different heights is evidently the result of the fuel evaporating through the plastic bottle, as the caps are screwed down tight.
About a week ago I decided that I had not learned much from this test, as it only shows what happens if you store the fuel in a tightly sealed fuel container. I was seeding my lawn at the time and I dumped the Avgas, Shell 96 and CountryMark fuels into the seeder fuel tank and they all ran fine. When I went to dump the pump gas w/ethanol into the seeder I noticed that there was something in the bottom of the bottle that was not mixed with the fuel. I am not sure if this is ethanol or water - but it is laying in the bottom of the bottle and does not mix with the fuel. I have not dumped this out yet, and I am going to drop some bare steel in the bottle and see if the metal rusts when in contact.
In order to get more useful information, I have decided to repeat the test with some modifications. I have drilled a tiny hole in the cap to simulate the fuel tank and carb vents - this will allow the bottle to better approximate the storage in a real fuel tank and carb. I have also placed a small piece of brass wire, a small piece of aluminum, and a small piece of bare steel in the bottle so I can see how they hold up when immersed in the fuel. I will also be placing these bottles out in my wood shed so they will be out of the weather - but exposed to the changes in outdoor temperature and humidity. The fuels in this test are Avgas 100LL, pump premium w/ethanol, Sunoco 96 racing fuel, CountryMark 90+, pump premium w/ethanol, pump premioum w/ethanol and Startron added.
This photo shows the brass wire, steel tubing and aluminum placed in the bottle.
I will give you all an update as the fuel ages. I really don't expect much to happen right away......I expect this to take a while.
Funny what some of us "gearheads" will do to entertain ourselves!
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