What is Ethanol Blended Fuel

Manufacturers generate ethanol, which is short for ethyl alcohol, by fermenting and distilling crops like corn, wheat and barley. It’s the same stuff that is in alcoholic beverages. Alcohol is an amazing cleaner and solvent and its natural tendency is to bond with water. There is where the problems lie. Unlike automobiles, boats don’t go through gas as quickly. Where a car might fill up every week, boats often sit for weeks on end with the same gas in them.

What happens is a process called phase separation where the alcohol separates from the gas and alcohol bonds to any water that is inherent in the system, corrupting all of the fuel in the process. That is the second problem with boats as opposed to cars with ethanol. Boats live in a watery environment. There is a lot more water present all the time. Once a fuel tank has reached phase separation, there is no fixing it. The fuel really needs to be discarded.

Corrosion in a cross section of a fuel line from ethanol

The other issue besides the water is that because alcohol is such a good solvent and cleaner it can dry out, damage and corrode plastics, rubbers and cause pieces to flake, break off and travel into the fuel system of an outboard.

fuel injector has debris and fouling from ethanol build up and deposits

In Baggett’s case that’s what happened. He was unknowingly putting ethanol fuel that was at a much higher content than is supposed to be allowed into his boat and his boat was sitting for extended periods of time allowing for breakdown of fuel lines, filters, and other components that were creating deposits in other parts of the system.

fuel filter comparison - bottom right is new filter in one piece, top left is broken fuel filter with deposits on screen

As seen in the photos here. You can see fuel lines that were cut open and inspected to find the inner walls were deteriorating and flaking off into the fuel. The fuel lines themselves became very hard and brittle. The fuel filters got gummed up with debris which also lead to fouling of spark plugs. The fuel filters swelled and broke into two pieces. Spark plug injectors filled with gunk and failed to spark.

spark plug on the right is working fine but the plug on the left is fouled from ethanol

“I’m embarrassed that I let this happen,” Baggett said. “I honestly didn’t know that there was ethanol in the system and that it was doing this to my outboard.”

Some early warning signs that you might have a fuel system problem are constantly dirty and clogged fuel filters, sputtering and choking of the outboard, lack of power, premature rusting of parts, gunk and build up in the system and complete shutdown of fuel intake.

But the blame doesn’t necessarily lie solely with Baggett. Retail locations have been found to be unknowing victims of ethanol in their own gas, especially those supposedly with less than 10 percent ethanol. Stations using gas with less than 10 percent ethanol aren't mandated to put up signs to that effect either. Sampley has tested fuels in boats at more than 24 percent ethanol levels who purchased gas from stations with no ethanol signage whatsoever. You can purchase ethanol content testers to perform these tests on your own fuels if you have concerns.

Basically you’ll follow the instructions and place 25% or 50% water in the tube with graduations on it and then add your fuel sample, shake to mix and then wait was the ethanol will bond to the water. Then by performing simple calculations, you determine the actual amount of ethanol in the system.

Ethanol Precautions

Sampley and Baggett offered several suggestions on how to avoid these ethanol nightmares in your own fishing boats.

“If I could save one angler from going through everything I’ve been through in the last year, it would be well worth the time,” Baggett said.

The first and easiest fix can be to avoid ethanol fuels all together in marine outboards. Seek out those stations that adamantly announced and promote they use non-ethanol based fuels only. Avoiding the root cause of the problems is obviously the best solution in any case. Test the fuel if you’re concerned. Some stations may unknowingly be carrying ethanol fuels.

Another precaution is to use a fuel and ethanol stabilizer like Lucas Safeguard Ethanol Fuel Conditioner with Stabilizers. This product will stabilize the ethanol to a degree in your system until you can burn through it all. Gas has a shelf life of about 3 weeks. After that, octane begins to diminish. These stabilizing agents can prolong that. However they cannot change the nature of ethanol, and its natural tendency to bond to water.

Buy gas from busy gas stations because their fuel will be replenished more and fresher than a gas station not frequented as much.

Replace your fuel filters every 50-100 hours, and more often if you suspect you might be getting unlabeled ethanol fuels from your local station.

Avoid running your tanks when they get close to empty. If you have had phase separation, the bottom of the tank will hold the highest water content. You may be able to run the tanks low enough and then remove the bad fuel and discard properly. Check your state laws on rules governing this.

Final Thoughts

“I was plagued with issues that resulted from the effects of ethanol,” Baggett said. “The relationship with ethanol and me was quite volatile and it crippled me more than once this season. It’s been extremely humbling and costly.”

“Ethanol is the No. 1 reason we see in our shop for a blown powerhead,” Sampley said. “If left to do its dirty work, ethanol will make any and all rubber lines useless and cause plastic filters to swell and break. Just avoiding some of the common sense things can alleviate a lot of problems. Things like leaving if you see a station being filled by a gas tanker. That old fuel and water separation is being stirred up as new fuel is pumped into the holding tanks.”

Ethanol is here to stay. Anglers and boaters need to be cautious and aware of the impacts to outboards and fuel systems in vessels that spend their lives around the water. Take some extra precautions up front to avoid costly repairs and downtime on the water later.