The Devil in Your Fuel

Run your boat often, run your boat smart.

Water and debris in bottom half of filter means a visit to the shop is in order.

If it’s been three months or longer since you last ran your boat, consider having the fuel system serviced. If you’re buying a used boat which has sat idle for an indeterminate time, definitely get her in the shop before firing her up.

I was reminded of this while watching Wayne Watson remove the cowling on a pristine, garage-kept bass boat at Governors Creek Marine in Green Cove Springs. “Guy brought it in here and said it hasn’t been cranked in over two years,” said Watson. “Take a look at what comes out of the fuel filter.” He emptied the decomposed gasoline from the spin-on water-separating fuel filter. Sludge and debris littered the bottom of a plastic container.

Performing such analysis at home, you might see water, heavier than gas, sink to the bottom of the container. Shake it (careful not to spill), and if you see bubbles in there, resembling vinegar and oil dressing, that’s water. If you see what looks like coffee grounds or dirt floating in there, you need to consult a qualified mechanic. Cap and dispose of your sample at the hazardous waste drop station at your local landfill. Avoid any source of flame or sparks when you assess fuel or fuel system elements.

Water condensation in the fuel tank is another worry, particularly with the alcohol content in ethanol fuels. Alcohol absorbs water, setting off a cascade of problems. If you have a choice, look for ethanol-free gasoline (drive out of the way, if you have to), and never settle for greater than 10 percent ethanol (E10). Otherwise, consult a mechanic to ensure your fuel system components are ethanol-compatible; that should include the installation of a 10-micron fuel filter, as well as assessment of your fuel tank—which may need to be drained and cleaned to remove water and deposits.


One type of product which breaks down water in fuel and reduces phase separation associated with ethanol.

Fuel Stabilizers

Fuel stabilizers seldom cross the minds of most Floridians, but products like STA-BIL, STAR TRON or the engine manufacturer’s specified additive are a big help if you know the boat will sit for more than a month. Of course, the easiest thing to do is simply run the boat on a regular basis. “My boat hasn’t been in the ocean since last year,” said mechanic Wayne Watson, “but it gets run every month. I start with the flusher on it and let it run 15 to 20 minutes so that it gets to that full operating temperature.”

The goal is to prevent the vapor separation tank, or VST, from emptying as a result of evaporation. As gas evaporates, it leaves varnish in the VST. The fuel pump, exposed to oxygen, may rust. Either process may introduce damaging elements into your engine when you crank it. Result: Clogged injectors, possibly a blown powerhead.

Steer Clear of Trouble

Cable steering bugaboos represent another trouble spot for part-time boaters.

With inadequate maintenance and infrequent use, corrosion may cause the cable to “freeze up.” Hear the bang of metal on metal at the boat ramp? Safe to assume it’s a boater attempting to loosen the steering ram. Sometimes it works, often it doesn’t.

There are several grease fittings on most steering systems and about once a month they should get a fresh shot with a grease gun. Also shoot some grease on your finger and apply it to the metal ram—the bar where the cable attaches to the engine. With routine application of grease, you should be able to turn a small outboard back and forth with ease.

Even with regular service, cable bends are problem areas. This is where most of the friction occurs. Stiff steering on an otherwise well-maintained boat may be a symptom of trouble. Consult your mechanic, soon. When a steering cable breaks while the boat is on plane, the boat turns abruptly. If you happen to be standing up when it happens, you probably get thrown out of the boat. This is the main reason why they install kill switches on outboard boats.

On my own boat, I recently upgraded to hydraulic steering. There’s virtually no maintenance and much less susceptibility to corrosion. However, the cost is more than double that of the best cable system. Mine was about $1,000 with a new wheel. But about the only thing that can go wrong here is a fluid leak, and when that happens, you will know it by the slick on the water, or the sheen in your bilge. The other advantage to hydraulics is that the boat is much easier to steer, and there is virtually no feedback from engine torque. You can let go of the wheel and the boat will hold course.

–Vance McCullough