Installing A Remote
Fuel Filter

By John Tiger
Published: June/July 2014

Add an extra layer of protection for your motor.

Photo of installing Moeller filter
A new water-separating fuel filter can help ensure that your boating isn't
interrupted by water and contamination in your fuel.

Your boat needs a remote fuel filter. More specifically, a water-separating, spin-on, remote fuel filter. Inconsistent fuel quality practically mandates this easy-to-install accessory. While it's not as sexy as a new stereo, it could save your day when your local fuel dock pumps some waterlogged fuel into your tank, and it may even prevent serious engine damage.

More Than Just Gas

The alcohol content in most fuels is 10 percent. Ethanol is the alcohol that's used in gasoline, and ethanol attracts water. Fuel that sits in your boat's tank, especially if you don't use your boat for long periods of time, gathers condensation from temperature and humidity changes that occur every day. To have this water run through your engine's fuel system and then in its combustion chambers is never a good thing.

Tip iconBefore buying a filter kit, check the size of your boat's fuel line and note what type of fuel line you have. While most are rubber, some older and/or larger inboard or diesel engines may have brass or stainless fuel lines, which require different fuelline fittings.

Exacerbating the issue, electronic fuel injection (EFI) and direct fuel injection (DFI or DI) engines are more prone to problems when fuel quality goes down. Two concerns in particular tend to crop up. First, fuel hoses, connectors, injector pintles and tips, as well as carburetor parts like floats, fuel inlet needles, and rubber/plastic parts, are highly susceptible to corrosion and degradation when exposed to alcohol-extended fuels. Fortunately, the engine manufacturers have made good strides in remedying these problems by switching to alcohol-resistant materials in these parts. But keeping water and alcohol to a minimum even in these systems is still best.

Second, EFI and DFI engines are designed and tuned to run leaner to burn less fuel; the same technology that allows them to do this also makes them more finicky when it comes to fuel quality.

These potential problem areas make for a different kind of maintenance today; boaters must be more vigilant about maintaining their boat's fuel system. A great first step is installing a water-separating fuel filter.

Choosing The Right Filter

Photo of Moeller filter comparison
This Moeller filter kit features a sight glass. Note the older, smaller-capacity unit it replaced.

These filters are common and available in most marine dealerships, chandleries, online retailers, and big-box stores. You'll need a kit to perform the installation; the kit consists of the filter canister and mounting system, brass plugs and fittings for the fuel lines, and mounting screws. Many brands and kits are available; two of the best and most common are Racor and Moeller. Both brands are available with clear-sight bowls that allow you to see the water that's accumulated in the filter over time. Filters with a plastic sightbowl must be mounted outside of the engine space to meet ABYC standards.

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