Parker Engine Mobile OE: Racor Products Blog & Information - North America

Eight Things Every Northwest Boater Should Know About Fuel Filters


(The following is an reprint from Pacific Northwest Boating News, September 22, 2015: Marty McOmber in collaboration with Fisheries Supply)

When Seattle-based commercial fishing boats head towards the rough and tumble waters off Alaska for the season, they need to make sure their engines can run without problems all day and all night for weeks on end. So what do you think the most important spare part they bring with them is?

Fuel filters. And a lot of ‘em.

On any boat, fuel problems can happen at almost any time (and usually, the worst time) thanks to the challenging conditions that exist in fuel tanks. And bad fuel can stop your boat’s engine dead.

That’s why every boat should have a high-quality fuel filtering system installed — and every boat owner should know how and when to change the filters.

I spent some time chatting with George Schillinger, an expert in fuel filters with the Racor Division of Parker, and what I learned surprised me. Here are some of the common questions — and misconceptions — about onboard filters.

My engine comes with a fuel filter, so why do I need a secondary filtering system?

That primary filter might be enough for a car, but it isn’t designed to deal with the primary culprit that affects fuel aboard boats — water. You are asking for trouble if you rely only on the engine’s fuel filter. In fact, you might not even know you have a fuel problem until your engine starts sputtering to a stop. Just one trip to your local mechanic to fix engine injectors ruined by bad fuel will make the cost of a good secondary fuel filtration system seem like a bargain.

Why do boats have such a problem with water in the fuel tanks?

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Because all boat tanks are vented to the outside. Depending on where the vent is located, water can splash directly into the tank when underway. That’s bad enough, but even if the boat isn’t moving, water can easily make its way into your tanks. The fact is, your boat’s tank “breathes” a lot of moisture-ladened air — all the time. It happens as temperatures change during the day and night and when fuel inside the tank sloshes about. Over time, condensation inside the tank can lead to water in the fuel. Water can also get into your tank if the deck fill plate leaks or even if the place you buy your fuel from doesn’t properly filter it before it goes into your tanks. “Water happens when you use your boat or not,” Schillinger said. “You need to be prepared for it.”

So why is water such a bad thing?

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StartFragmentWater in your tank allows algae to grow which eventually produces sludge. Water and sludge can cause big fuel problems. If either gets into your engine’s fuel system, it can lead to costly repairs. It is also a safety issue. Water and sludge settle to the bottom of the tank. So if your boat hits bad weather, the agitation in the tank will stir up those nasty components and could cause your boat’s engine to die just when you need it most.EndFragment

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How does a filter stop water anyway?

Two ways. Water is heavier than fuel, so a good filter housing will use gravity and centrifugal forces to separate the water and then let it fall to the bottom of the filter housing. Recent advances in filtering materials have improved the filter element’s ability to block water while allowing fuel to flow through. Think of it like a breathable rain jacket. Good filter housings will have a glass or plastic bowl at the bottom so you can see if water is collected. It should appear as a pretty clear line in the bowl, which will alert you to a problem.

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Okay, so I need a secondary fuel filter. What size of a filter system should I get?