Commissioning and Maintaining Your Boat’s Fuel by John Conlan From News From The Bow

Article reposted with permission from News From The Bow.

The time for spring commissioning is upon us. You may be thinking about rigging checks, engine tune-ups, water system inspections, and checking heads…but what about your fuel? Just because you put fuel stabilizer in your tank(s) in the fall doesn’t mean you can safely start up your engine(s), and motor away in the spring.

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Maintaining Fresh Diesel Fuel

 Sailboats

If you store diesel fuel on your sailboat, where a lot of it isn’t consumed during the course of a season, then a “biocide” should be routinely added to the tank. Biocide should be an integral part of fall commissioning, and be included with each added tank of fuel during the season. Examples of biocide products include Killed (made by FPPF) and Biobor J F (made by Hammonds). These products prevent fungus and other microbial life from growing in diesel fuel.

It is also not a bad idea to add:

• A “cetane booster” and
• A lubricity additive

each spring to rejuvenate fuel. FPPF products offer a full line of additives that can be used for these purposes. Starbrite Company offers another useful fuel additive for diesel, called Starton, that disperses water, maintains the cetane level (but doesn’t replenish it) and cleans the fuel system during use.

Power Boats

For power boaters with diesel engines a product like MDR’s Water Zorb is a good idea after winter storage. Its job is to disperse water in the tank. During the season two other products that help maintain fuel include:

• FPPF’s “Fuel Maintenance” that combines a Cetane booster and lubricity addictive, and
• Startron Additive that disperses water, helps maintain the cetane level, and cleans the fuel system as it burns through

Ethanol Gas Concerns

Many people think skulls and crossbones when they hear the word “ethanol”. The truth is that ethanol gas was originally introduced as a cleaner, more environmentally friendly alternative to fossil fuel. Unfortunately, the nature of ethanol is that it attracts moisture. As a result of this, when you buy ethanol gas right from the pump you also receive 4 teaspoons of water in every gallon of gas.

It is the nature of marine fuel applications that create problems with ethanol containing gas. We on the water are really the only one’s affected in a negative way by ethanol. This is because our gas tanks must be vented, our environment is generally high humidity, and our season usually lasts no more than 6 months. As a result of these factors gas sits in our tanks, especially over the winter, is exposed to a moist environment, and accumulates water.

Ethanol gas changes as it sits in a fuel tank. After about 30 days the gas starts to “phase”, or separate. This means the following: at the bottom of the tank the water settles, in the middle is the layer of ethanol, and on top floats the gas. Products like Startron for gas, or Green Stabil, or MDR Extend, slow down this process.

In addition to the moisture that enters through our tank’s vents, gas also loses octane during storage, as much as 10 to 15% is depleted over a winter. Suffice it to say, the gas you put in a boat’s tank in the fall is not the same quality gas you have in the tank in the spring.

It seems that nearly every boater has an opinion about how gasoline should be stored. Some say, “Fill the tanks up”. Others say, “Let it run down and store the tank dry”. I am more inclined to recommend the latter because, regardless of what you do, fuel will lose octane and gain water during storage. For me ¼ tank of poor quality gas is easier to deal with than a full tank of poor quality gas. I suggest adding stabilizer and letting your tank run down in the fall. Then, in the spring, add water Zorb (for gas) and a couple of gallons of fresh gas. Then run the tank down. You can then fill up, add the fuel additive of your choice, and hopefully enjoy a season without gas-related problems.

Mercury, Yamaha, and other engine companies recommend their own fuel additives. You can also use Stabil, Startron, MDRE Zorb, Extend, and Phase Guard 4 because ALL of these products are compatible with each other.  Please note that, if you have a steel or aluminum tank, your best choice during storage may be Phase Guard 4 because it is the only additive that includes a rust inhibitor.

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Other Ways to Protect Your Fuel During the Season

With gas prices going up I am sure boaters will be buying gas when prices are low, and possibly using their engines less. During times like these it is particularly important to use additives each time you fill up in order to keep your fuel fresh.

Water separating filters are of utmost importance when using ethanol gas. These filters trap moisture in their element and prevent it from getting to the engine. All of these types of filters, whether you buy Racor or aftermarket spin-ons, work the same way. The filter element is treated with a chemical called a Colacer, which holds moisture in the element until it forms a drop of water. This water then drains to the bottom of the container. Once the filter becomes saturated it needs to be replaced.

Prior to ethanol containing gas we recommended changing these filters annually. Now we suggest changing water separating filters every 50 to 100-engine hours. The more you use your boat the less often you need to change this type of filter, because you will be accumulating less moisture in the tank.

Contaminated fuel tanks in general, whether gas or diesel, can benefit from tank cleaner additives. Startron makes a tank cleaner that dissolves particles in the tank, and allows them to be burned through with the fuel. Be aware that this product must be added to fuel tanks at the same time as gas or diesel. It only works when it is mixed with fuel, and only cleans what it touches. It is a great product, and adding it is a lot less expensive than having to empty, clean and refill a contaminated tank.

The last problem with ethanol is that it polishes metal and aluminum tanks by pulling growth off the inside of the tank. This growth can then clog your filters, or get into the engine and clog injectors and jets. We therefore recommend using a 10-micron fuel filter between your tank and engine.

I hope the above advice provides some insight into commissioning and storing your boat’s fuel. If you have any questions don’t hesitate to ask.

Editors Comment: You can reach John directly with questions or comments at (732) 721-1605, or via his email: john@lockwoodboatworks.com.

More great articles like this can be found on News From The Bow.