corke board | by Mark Corke
Fuel Rules Keep your gas or diesel engine running smooth.
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ccording to BoatUS, one of the main reasons that boaters call for help on the water is because of mechanical breakdowns; and of those calls, the vast majority are attributable to fuel issues. Of course, some of these instances may be folks that have simply run out of gas. Often, however, the situation is a little more complicated — like problems with the fuel delivery system itself. Unless your boat has a small outboard engine hanging off the back, chances are you have a separate fuel tank on board containing either gasoline or diesel. In most cases, the fuel is pumped from the tank through a filter and then into the engine. “Pumped” is something of a misnomer here because the pump is often attached to the engine and actually sucks the fuel to the engine, rather than pushing it away. This may seem like semantics, but understanding this difference is important — especially with regard to diesel engines in particular, as any leak on the suction side of the pump will allow air into the system and will stop the engine from working.
Engines should have an easily accessible fuel filter, shown here in white (top). A drain in diesel filter bowls allows water and other contaminents to be drawn off (below, right). Long-range cruisers often have an impressive array of fuel filters (bottom left).
Hoses Getting fresh fuel to the engine is critical for both diesels and gas engines; old or dirty fuel will clog carburetors and injectors, cause miss-firing, block filters, and either make the engine stop or cause it to run at reduced power. To ensure proper operation, check your fuel hoses. Make sure hose clamps are tight. A leak will undoubtedly make the boat smell, or, worse yet, potentially cause a fire. On gas-powered boats, hoses should be marked as suitable to support delivery of ethanol fuels. Many hoses on older boats were installed before ethanol was of concern to the marine industry. These older hoses may look okay on the outside, but the ethanol contained in the fuel will actually eat away at the hose lining, causing small particles to get washed down with the fuel and eventually block critical system components. Hoses capable of transporting ethanol fuels will be marked A1 or A2, and these designations will actually be
Mark Corke is an accomplished journalist, author and sailor. He’s the creator of the popular blog onboardwithmarkcorke.com, which focuses on various DIY boating projects.
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ApRil 2014
printed on the hose’s exterior. I should add that ethanol also is incompatible with fiberglass fuel tanks, which are sometimes installed on older boats.
Filters Another ally in ensuring good quality fuel reaches the engine is good quality filtration — and changing filters according to the engine manufacturers’ recommendations is probably the biggest single thing that you can do to protect your engine from bad fuel. At a minimum, there should be at least two filters between the fuel tank and the motor. Normally this would include a primary filter, which removes dirt, water and other contaminates that are present in virtually every gallon of fuel; and a secondary, smaller filter, which exists to catch particles that made it through the primary filter. Filters, however, can only do so much. If fuel is excessively dirty, has a lot of water in it or is old, then it will not properly combust — even if it does make it to the engine. Ethanol gasoline is particularly prone to a phenomenon known as phase separation. Phase separation is the process by which gasoline loses something called its “cetane” rating. Some reports suggest that gasoline starts to break down in as few as 30 to 60 days. Adding a fuel stabilizer helps preserve fuel in the tank, and it’s probably wise to do so every time you fill up.
Diesel Much like gasoline, diesel fuel also is prone to degradation, primarily from algae and microscopic bugs that actually grow in the fuel. Algae and diesel bugs present as sludge, which gums up filters, fuel lines and injectors. As is the case with gasoline, there’s evidence that adding an additive fuel stabilizer with a biocide to your tank of diesel each time you fill up helps prevent this problem. Conventional wisdom says that tanks should either be completely full or completely empty when vessels are laid up for long periods. Tanks that are half full have a large air space contained within. During temperature changes and alterations in humidity levels, moisture-laden air will find its way into the tank and condense on the tank’s sides. This water, which is heavier than the fuel, sinks to the tank’s bottom, only to be picked up by the fuel delivery tube. Keeping the tank topped off means less available space for moisture to condense, thus forming less water. LB
photos by mark corke