I have been reading about some of the problems people have been having with E10 fuel lately because I had some myself. This is about my boat but it still applys to small engines and our cars and trucks. Hope it helps somebody out. It is a cut and paste form a cut and paste from another site so please parden the duplications. It's kinda long.
""""I left about 12 gallons of fuel in my 17.5 gallon tank from late fall till early spring this year. Normally not a huge problem until the dreaded E10.
I always start the boat in the drive before taking it out. Did so started great. Was going to take a bud out on the Susky flats a few weeks ago and boat would not start at the ramp. Started ok when I got home. Thought the carbs or fuel pump might be problem but somebody at work told me about a very expensive problem with his motorcycle so I did alot of reading on the web and learned a few things. Some of which I've verified this last week in person.
E10 has a shelf life of 30 days without stabilizers.
Regular old style stabilizers don't work they are mainly (suprise) alcohol.
You need a new style fuel stabilizer that's made for E10. Then you may get 90 days if your lucky.
The ethanol in E10 will aborb water from the atmosphere if the vent is open and humidity is high. When the alcohol has absorbed all the water it can hold it will seperate from the fuel in layers. This leaves a bottom layer of ethanol and water and a top layer of low octane gasoline. Neither of which your engine wants to run on. This is called Phase Seperation.
Water in the fuel can be especially damaging to 2 stroke engines. The alcohol cleans the oil off of the places you want lubricated and the water sticks to these clean surfaces and can cause pits and rust, things like bearings and cylinder walls.
Starbrite and others makes a stabilizer that is recommended on several marine sites.
http://www.starbrite.com/sproductdetail.cfm?ID=1537
There is a product that claims it makes phase seperated fuel go back together and become usable. It seemed to work for me.
http://yhst-37334516642247.stores.ya.../mdreware.html
There are a few companies that make kits to test for the amount of water, ethanol or both in fuel. I bought and used one from this place.
http://www.fuel-testers.com/
The alcohol is added locally at the tank farm as the truck is being loaded. this is because of the short shelf life of E10. It also means that the amounts are not always accurate. may be 10% may be more or less. If it is mcuh more you can have all kinds of serious problems with your fuel system.
There is no independant testing of the fuel for mixture % and water. It's up to the distributor.
The fuel pump may or may not tell you that there is E10 in the pump. Most states don't require it.
Below is cut and pasted from a write up I did on another forum desrcibing my experience. sorry about any double info.
I don't represent or have any interest in these products other than using them recently.
I hope this helps someone else from having problems or spending money on repairs.
"I posted above about my boat starting and rough running problems. I thought it was related to ethanol and water seperation. It was!
Last time I took the boat out it was real hard to start which is not normal for this boat. It also ran rough. I did some web reading and learned alot about the problems of E10 gasoline and water seperation. so I ordered the E-zorb and startron stabilizer above and an E10 fuel test kit from this place.
http://www.fuel-testers.com/
In the meantime I borrowed a small 6 gallon outboard fuel tank and filled it with clean new 50:1 mix for my outboard. My boat has a 17.5 gallon tank.
Before I took the boat out this weekend I started it in the drive and then disconnected the line from the tank(quick disconnect) and ran it till it stalled. I figured this would burn up all the bad gas in the carbs and fuel line. I then hooked it up to the temp 6gal tank with good fuel. It started right up. I wanted to make sure I didn't have problems at the boat ramp again.
In the meantime the E-zorb and fuel stabilizer came in. So I added both to the tank of suspected bad gas. E-zorb claims it will make "Phase Seperated Gas" usable again. Phase seperation occurs when the ethanol in the fuel aborbs all the water it can hold and seperates from the fuel. Water and alcohol on the bottom low octane gas on top. Motors don't want to run on either.
I went out on the river yesterday and started the boat and ran on the NEW tank for a while. It ran much better! Once I figured everything was good I switched back to the OLD tank that I had added the chemicals to. The boat now ran fine on this but it did smoke a bit on startup. I suspect that was steam! I ran most of the old bad gas out of tank and it ran fine. I hooked up the new tank shortly before leaving the water to make sure I had good gas in the fuel line and carbs.
When I got home yesterday the fuel test kit had arrived. Today I tested the OLD fuel and big suprise it had seperated. Also this E10 was only about 6% ethanol and water! I tested the NEW gas and found that there was a very small amount of water in it as well.
It seems the E-zorb worked enough to make the Bad gas usable.
The fuel test kit is bit pricey for what is included but you need the kit to find out how much % of alcohol is in the fuel. It works like 90turbo1 test above but you add a test solution to the mix to dye the fuel. Seperation is easy to see as the different components(fuel, water, alcohol) turn different colors of blue. If you just want to check for water in the fuel you just need the dye solution and a small glass container with a lid. I think this kit is a good thing to have around. I will now add the e10 stabilizer and E-zorb to every tank and can of gas i have. And I will not keep fuel longer than 90 days anymore. The problems just aren't worth it. E10 only has a shelf life of about 30 days untreated. And as I have found out it may have more or less than 10% ethanol and some water already in it at the pump!"
I also installed a water seperating fuel filter on my boat today!"""""