ethanol , how to prevent contamination ?

In my particular case, (4 cars, 2 M/Cs etc....etc...) contamination WOULD be theoretical, since I use different fueling and maintenance practices than you do, and thus far fuel fouling just hasn't been much of a 'thing' in my life.

In your case, the contamination appears to be 'real-world'...and I would maybe try to heed some of the advice that people have been trying to give you.
Your call.

 

Sorry, but you essentially said the bikes are in a secure area. Does the kid like biking?

 

I had a dream last night........about OLD vehicles with plastic gas tanks and ethanol fuel.
No, really.

What year model is this bike ?

You do know that vehicles older than about 1980 are NOT supposed to have ANY ethanol in the gas.......right ??
Maybe your plastic gas tank is not ethanol compatible and that is melted tank lining that you are seeing in the fuel.

 

OK, scratch another "possibility" off the list.
You may never get an exact answer.

Any chance that some diesel fuel could be involved ?
Yes, time for WILD guesses.

 

I thought that I was being proactive by adding an inline fuel filter to my 5k generator.

I keep the fuel tanks topped off when my gadgets are stored for the off season.

I ran my generator last Fall and after running it for 20 minutes I shut off the fuel supply and let the engine run until the fuel bowl ran dry. 4 months later I switched on the fuel and couldn't get the engine started.

The fuel filter that I added was clear plastic. I discovered that the fuel in the filter was an orange/brown color. I removed the float bowl and switched on the fuel shutoff valve. I let it drain until the fuel in the filter ran clear. I replaced the float bowl and after a couple pulls, the engine started right up.

The orange stuff must be less flammable. My adding the fuel filter may have added a reservoir at a low point in the fuel line for the degraded fuel to accumulate in. I am guessing that when I turned the fuel on, it filled the filter and my float bowl with the orange stuff. This was surprising since I put Stabil in the tank when I topped it off. Maybe I didn't run the engine long enough for the Stabil to mix with all the fuel?

Does the fuel in the tank stratify after sitting for 4 months? Why was only some of the fuel in the tank contaminated? Was the good stuff at the top of the tank and the crud settled to the bottom of the tank?

I found this explanation for long term storage problems with ethanol/fuel.

"Ethanol attracts water. When the two get together, they create the perfect environment to grow a type of bacteria called acetobacter. The acetobacter excrete acetic acid. Acetic acid is very corrosive. If you’re refilling your gas tank every week or two, acetobacter don’t have time to grow a sufficient size colony to damage metal parts in your fuel system. If your fuel sits for longer periods of time these microorganisms continue to multiply until your gas tank contains damaging levels of acetic acid."

This explanation doesn't explain whether or not the contaminated ethanol precipitates out to the bottom of the tank but I suspect that it does.

There are no E0 gas pumps at gas stations around central Ohio. My solution was to go to a nearby boat dock and buy 5 gallons of straight gas to top off my off seasonal small engines. Ethanol is not added to Marine fuel for obvious reasons. It is a pain hauling a 5 gallon can the 100 yards from the dock to my car and the fuel is twice the price but it solved my starting problems for my seasonal small engine gadgets.

 

FWIW, acetic acid is vinegar.

 

You almost got that right.
Vinegar is weak acetic acid.
But not all acetic acid has anything to do with vinegar.

 

Water is the heavier component. Unless the fuel is circulated in some manner, there will be stratification with higher levels of water at the bottom. This also happens in your brake lines.

Stabil protects the gasoline from oxidation and degradation. It won't keep water out, nor prevent phase separation.

I don't see how that could be. Acetic acid bacteria do convert ethanol to acetic acid, but have a limit to how much ethanol they can tolerate. They'll spoil beer, wines, and cider, but not distilled spirits. The most the hardiest strains can handle is 15.5%. The amount of water needed in E10 to dilute to those those levels would almost equal the amount of gasoline.

There are bacteria that will grow and eat petroleum products. They a concern in diesel and heating oil tanks because they can clog lines and filters over time. It's possible that the presence of ethanol and water could make them more of a concern with sitting gasoline. Then the degradation of the fuel can lead to productions that can precipitate out.

Vinegar is a minimum 4% acetic acid, which what most vinegars found at the grocery store contain, though it can be as high as 18%. 20% seems to be the highest level the bacteria that make it can tolerate. So vinegar can be thought of as the beer or wine of the acetic acid spectrum, with higher concentrations requiring the acid to be separated from the water of the vinegar. Pure acetic acid is a clear, colorless liquid, and is commonly referred to as glacial acetic acid

 

I was thinking about how that moisture gets introduced to the fuel in the generator's tank. On a motor vehicle, the fuel tank is part of a closed system complete with a vapor canister.

Small engines don't have that system. Most have a gas cap with a pinhole vent in it. The tank needs to be vented to allow it to breathe so that outside air replaces fuel as it is consumed.

The problem with that simple system is that during the months that my generator is stored, it experiences a daily thermal cycle. It is cooler at night and warmer during the day. At night the cooler temperatures cause the fuel to contract a bit and so the tank inhales a bit of moist outside air. During the day, the temperature rises, the fuel expands a bit and it will exhale a little air from the tank. That daily breathing introduces moist air into the fuel.

In the old days, with straight gasoline, a few drops of water might appear at the bottom of the tank. With E10, they advise to keep the tank full in the Winter which just limits the volume of air space above the fuel and also provides the maximum amount of ethanol to absorb any moisture.

If the fuel sits for months the fuel stratifies with the best being at the top of the tank. The ethanol may not be able to absorb all the moisture and what appears on the bottom of the tank is the less flammable orange stuff or in worst cases white, jello-like gooey stuff.

I have rebuilt the carburetor on my sisters outboard boat motor after it sits over the Winter. She fuels it from a 5 gallon can of E10. Using ethanol on the water is probably the worst case scenario. The bottom of the float bowl and the jets are covered with a white gooey residue.

I also don't know what happens to the chemistry of stored gasoline. My motorcycles run in the Spring on stale gasoline but they always run better after the first Spring fill up.

 

I thought the recommendation for keeping the tank full for storage even applied with straight gas. It meant less air, thus less oxygen to do its thing, which leads to a different kind of gunk in the tank. I know E10 is more likely to cause problems, but small engine manufacturers didn't won't people storing their products like most people did. Growing up, we didn't do anything special with regards to storing the lawn mower end of season. It just got rolled into the shed with whatever fuel was in the tank.

IIRC, the gas cap for a small engine is considered a wear item, and needs to be replaced every few years. Mainly because of evaporative emissions, but if it is easier for stuff to get out, it is easier for stuff to get in. Which brings up another source of fuel aging and contamination. It is the lighter factions of gasoline that come off with evaporation. Leaving heavier stuff behind that doesn't burn as well on its own. Someone experimenting with a fuel vapor system reported the fraction left in the tank after everything else was gone wouldn't burn on its own.

 

You could avoid all these problems by replacing your gas cap during the off season with another non-vented one to create a sealed system.

You might have to do the modification yourself.

 

Fuel in the carb bowl will still be exposed, but that is a much smaller amount to deal with.

 

That is a good idea but it is easier said than done for me. Each piece of my equipment has a different size or type of cap. Some are metal, some are plastic. and on my motorcycle, the cap is hinged to the tank. Probably the best approach for me is to drain the tanks completely and then run the engine until the carburetor float bowls run dry. I may be able to burn the gas in the car and buy fresh in the Spring.

 

I went with drain the tank, and run the tool dry. Then added some alcohol or acetone added to the first tank of the new season in case anything was left in the carb.

Then I swapped to electric for the lawn tools.