Beware of Foul Fuel in Used Boats

When you’re buying a used boat, you may decide to do the full inspection yourself, or hire a marine surveyor to confirm the boat’s condition. Either way, one of the more difficult tasks is to judge the condition of the boat’s fuel system. Water in gas, particularly ethanol-boosted gas, is quite common in pleasure boats that go unused for prolonged periods. The ethanol actually attracts moisture, which is why tanks should be topped off during storage periods, leaving less room for condensation. Water can also intrude into any boat through poorly sealed fuel caps and vents.

Constant vigilance and regular maintenance of fuel filters against water and sediment in fuel systems can prevent expensive engine problems and tank corrosion.
Constant vigilance and regular maintenance of fuel filters against water and sediment in fuel systems can prevent expensive engine problems and tank corrosion.

Microbes that feed on hydrocarbons and cause sludge can only flourish if water is present. These same algae emit sulphuric acid as a waste product, which corrodes tanks, pumps, and injectors. In diesel engines, too, given that 90 percent of all problems are fuel-related, fuel system inspection should be an area that gets close attention.

Water or debris in the fuel can be an indicator of deeper problems, namely lack of maintenance, or fuel tanks that are contaminated. So, when a surveyor gets onboard for an inspection he will typically check the condition of engine hoses and fuel filters prior to running an engine.  However, some boats that are serviced at layup may show new hoses, clean bowls and filters, yet still have problems in the fuel tanks.  When running the engine, look for black smoke, lack of power, or hesitation in acceleration as further indicators of fuel problems

A surveyor should check for water in tanks by using a water-indicating paste, and whenever possible visually inspect the inside of tanks.  After running an engine, he should also recheck the filters.

Simply adding products like Biobor to a fouled system will only bring the problem past the filters and into the engine.  Biobor and similar products should be used as preventatives, not cures. The only real cures for fuel contamination are to completely replace the fuel and dispose of the old fuel properly, or hire a company to do fuel polishing (filtration) along with a thorough tank cleaning. The presence of algae, discoloration, or sediment should not necessarily kill a sale, but you would be prudent to request that the owner pay for fuel polishing or tank cleaning from a reputable professional.

The worst case scenario is finding that you’ve bought a boat with corroded tanks that need replacing. This will be an expensive problem, particularly if they’re baffled custom tanks, or, as is the case in many pleasure boats due to the manner of construction, require that the decks be cut away.

So when you’re thinking of buying a used boat, any extra time you or your surveyor take to make sure of the quality of fuel will be time very well spent. Good hunting.

An earlier version of this post was published on Boat Trader in 2011.


Ethanol and Boat Fuel: Stay Vigilant

If you’re new to boating and are looking at used boats to buy, you might not be aware of the running battle boaters have been waging with ethanol-based fuel for years. Ever since the widespread introduction of ethanol-blended fuel in 2006, many boaters eith gasoline-powered engines have experienced performance problems directly related to the added ethanol in gasoline. Boats with fiberglass fuel tanks are particularly susceptible. Read on.
A combination fuel filter and water separator will collect water in a clear reservoir at the bottom. Keep a close eye on that reservoir and drain anywater out right away
A combination fuel filter and water separator will collect water in a clear reservoir at the bottom. Keep a close eye on that reservoir and drain anywater out right away

What is Ethanol, and Why Does It Cause Problems?

Ethanol blended gasoline was introduced in the United States as a renewable fuel alternative that would help reduce dependence on foreign oil. Because ethanol is derived from corn, the production and refinement of ethanol supports the agricultural industry and rural communities. Burning ethanol gasoline also produces 3 to 4 percent fewer greenhouse gas emissions than pure gasoline. The growing adoption rate of ethanol has escalated in recent years and use is even mandated in some states.

Although ethanol blended gasoline has caused little to no issues on cars, the use as marine fuel has caused quite a few problems for boat owners. The problems are mainly linked to the fact that ethanol is a solvent that can react with boat fuel tanks, fuel filters, and carburetors, causing an engine-stopping sludge. The ethanol solvent interacts with water that forms from condensation that commonly gathers in a partially full fuel tank. Because ethanol is a hygroscopic, it attracts and attaches to any water in a fuel tank, creating a clogging sludge that is problematic for fuel filters, carburetors, and engine parts.

Fiberglass fuel tanks typically found in older boats are made with a resin that can also react negatively with ethanol-blended gasoline. The sludge build up can cause performance issues, ongoing repair or maintenance issues, and can even ruin an engine.

Ethanol Related Boat Engine Problems

The use of ethanol blended gasoline can wreak havoc on your boat engines if not carefully monitored. To limit the impact of ethanol problems in boat engines, consider these precautions:

  1. Don’t let ethanol gasoline sit in fuel tanks. Ethanol gasoline sitting too long in a fuel tank is more likely to absorb water and cause problems. Use fuel within 90 days and refuel often to prevent problems.
  2. Keep up with maintenance. Be sure to change fuel filters and maintain a clean carburetor to limit sludge build-up caused by ethanol in your boat engine. At every fill-up, use a good fuel additive.
  3. Address issues quickly. When performance problems persist, such as a continually fouled carburetor, consider taking the proactive measure of draining a fuel tank and refueling. Cleansing your fuel tank of any gasoline impacted by ethanol may save you from bigger issues like a destroyed boat engine. For more on this see How to Get Rid of Bad Boat Fuel.
  4. Choose ethanol-free fuel. You may have options for avoiding ethanol gasoline altogether. Some marinas now offer ethanol-free fuel or fuel with additives that may reduce the impact of ethanol in gasoline.
  5. Fuel your boat at marinas. Don’t risk fueling your boat with a higher level of ethanol if E15 becomes available at gasoline stations on land. Fueling your boat at a marina will be safer because E15 is not approved for sale at a marina.

Concerns over Increasing Ethanol from E10 to E15

In 2010 the EPA approved an increase of  ethanol in gasoline from 10% (E10) to up to 15% (E15). Availability is not widespread, and the EPA has stipulated that E15 cannot be used  in a variety of vehicles and machinery, including boats. Still, the National Marine Manufacturer’s Association (NMMA) and other boating industry groups have warned that “there is significant risk of consumer confusion and misfueling.” Experts are concerned that even though E15 may not be offered at your local fuel dock, there are many owners of smaller boats who choose to purchase their gasoline on land at standard gasoline stations. Also, the marketing of E15 as a lower-cost fuel may be attractive to boat owners who aren’t informed about the potential impact on their boat’s fuel systems and engines.

So be vigilant. With ethanol, an ounce of prevention is worth several pounds of cure.


Ethanol’s Worst Enemy

Alcohol has the power to ruin lives if you let it. It also has the power to wreak havoc on a boat’s fuel system.

If you need a bit of background, ethanol is used to “oxygenate”  fuel to help reduce hydrocarbon emissions that cause air pollution. Of course, the best alcohol is derived from malted barley and comes in a bottle marked “Product of Scotland,” but alcohol used for ethanol can be made from cellulosic materials such as corn stalks, grain straw, paper, pulp, wood chips, municipal waste, switchgrass, and other sources.

Volvo-Penta's new treatment should be a potent ally in the war against water in marine fuel.
Volvo-Penta’s new treatment should be a potent ally in the war against water in marine fuel.

The major problem with ethanol, particularly for marine engines that sit long between uses, is that ethanol oxidizes and can absorb water. That can cause corrosion. For example, E10 can hold approximately one half of one percent water at 60° Fahrenheit. At lower temperatures, such as 20 degrees Fahrenheit, E10 can hold less, about 0.35% water, which still means 0.45 ounces in a gallon.

So when I learned that Volvo Penta had introduced a new fuel additive to protect marine engines from the harmful effects of ethanol, I took notice. Suitable for any outboard or sterndrive system, Volvo Penta recommends using it every time you fill up with ethanol-blended gas to protect your engine from damage.

“Ethanol-blended fuels such as E10 and E15 are approved by the U.S. Environmental Protection Agency for the automotive market, but ethanol damages marine engines and fuel systems due to the corrosive properties of alcohol,” explained David Kennedy, director of parts and accessory operations for Volvo Penta of the Americas. “Unlike automobiles, most marine engines are only operated intermittently. Today’s oxygenated and ethanol-blended fuels can begin to oxidize in as little as 30 days if left untreated in the boat’s tank, resulting in corrosion inside the engine and fuel system.”

Formulated with antioxidants to combat fuel breakdown, the new fuel treatment also contains chemical corrosion inhibitors that form a protective barrier on fuel system components. For some reason, Volvo Penta points out that it contains no alcohol. Well, duh. What caught my eye is that 12 ounces treats up to 60 gallons of fuel and keeps fuel fresh for up to one year.

If I were to take delivery of a used boat, this new fuel treatment likely would be one of the first things I would put on my shopping list.