Beware of Foul Fuel in Used Boats

When you’re buying a used boat, you may decide to do the full inspection yourself, or hire a marine surveyor to confirm the boat’s condition. Either way, one of the more difficult tasks is to judge the condition of the boat’s fuel system. Water in gas, particularly ethanol-boosted gas, is quite common in pleasure boats that go unused for prolonged periods. The ethanol actually attracts moisture, which is why tanks should be topped off during storage periods, leaving less room for condensation. Water can also intrude into any boat through poorly sealed fuel caps and vents.

Constant vigilance and regular maintenance of fuel filters against water and sediment in fuel systems can prevent expensive engine problems and tank corrosion.
Constant vigilance and regular maintenance of fuel filters against water and sediment in fuel systems can prevent expensive engine problems and tank corrosion.

Microbes that feed on hydrocarbons and cause sludge can only flourish if water is present. These same algae emit sulphuric acid as a waste product, which corrodes tanks, pumps, and injectors. In diesel engines, too, given that 90 percent of all problems are fuel-related, fuel system inspection should be an area that gets close attention.

Water or debris in the fuel can be an indicator of deeper problems, namely lack of maintenance, or fuel tanks that are contaminated. So, when a surveyor gets onboard for an inspection he will typically check the condition of engine hoses and fuel filters prior to running an engine.  However, some boats that are serviced at layup may show new hoses, clean bowls and filters, yet still have problems in the fuel tanks.  When running the engine, look for black smoke, lack of power, or hesitation in acceleration as further indicators of fuel problems

A surveyor should check for water in tanks by using a water-indicating paste, and whenever possible visually inspect the inside of tanks.  After running an engine, he should also recheck the filters.

Simply adding products like Biobor to a fouled system will only bring the problem past the filters and into the engine.  Biobor and similar products should be used as preventatives, not cures. The only real cures for fuel contamination are to completely replace the fuel and dispose of the old fuel properly, or hire a company to do fuel polishing (filtration) along with a thorough tank cleaning. The presence of algae, discoloration, or sediment should not necessarily kill a sale, but you would be prudent to request that the owner pay for fuel polishing or tank cleaning from a reputable professional.

The worst case scenario is finding that you’ve bought a boat with corroded tanks that need replacing. This will be an expensive problem, particularly if they’re baffled custom tanks, or, as is the case in many pleasure boats due to the manner of construction, require that the decks be cut away.

So when you’re thinking of buying a used boat, any extra time you or your surveyor take to make sure of the quality of fuel will be time very well spent. Good hunting.


An earlier version of this post was published on Boat Trader in 2011.

 

How to Get Rid of Bad Boat Fuel

Good filters and water-separators like the combination unit shown here are essential, especially after a bad-fuel episode and a fuel system reboot.
Good filters and water-separators like the combination unit shown here are essential, especially after a bad-fuel episode and a fuel system reboot.

Going through the frustrating process of dealing with bad marine fuel? Be it diesel or gas, you’ll want to know how to start fresh and completely eliminate the problem. Bad fuels can come from water (condensation), debris (dirt or metal oxidation-rust), algae or varnish build-up as fuel ages.

The first signs of contamination can be seen in your fuel filter. Keeping the filter clean goes a long way to keeping your engine running right. I recommend an in-line fuel filter placed before the fuel pump. This will keep the pump from wearing out due to the contaminants.  If you suspect water contamination, sound the tank for more water (it will be on the bottom of diesel tanks and can be measured by water-activated paste on a sounding stick). You may want to invest in a water-separation filter like a Racor filter if you have persistent condensation problems. Whatever the cause of the problem, a thorough flushing of the fuel tank, a change in filters, and the proper disposal of old bad fuel is the only way to get a fresh start.

Hopefully, we’ve come a long way since the days when we dumped old oil down the storm drain, poured old gas on the ground or, in my case, when we used waste oil to grease a marine railway instead of getting rid of it with less impact to our environment. I was the ops manager of a 100-year old boatyard undergoing a massive infrastructure makeover; eventually we transitioned to be a “small” producer of hazmat material, and there were proscribed ways of handling contaminated fuels. But first we had to get rid of the backlog of used oils, foul fuels, and contaminated bilge water found everywhere in various containers among the 14 buildings about to be demolished. Dealing with everything from hundreds of cans of old paint to waste oil and barrels of contaminated fuel helped me understand how to dispose of it all in the best way we presently know how.

For diesel-powered boats, an inline fuel-polishing module can prevent a lot of woes.
For diesel-powered boats, an inline fuel-polishing module can prevent a lot of woes.

This large quantity of bad fuels and oils led directly to our advice to individual owners on how to deal with their boats’ old materials:

  • Don’t ever leave it by the dumpster. Go to the marina office for direction; they’d much rather deal with the fuel and oil through their systematic process than see it go in the trash or be spilled on the ground. In many cases they will advise you how to take it to a local recycling center, or will gladly take it themselves. Local recycling centers actually make money by recycling everything from oil to old batteries, and without much cost to you beyond the expense of an annual town sticker on your car.
  • Don’t ever dump even small amounts of fuel or oil on the ground. You know why!
  • Find someone with a waste-oil heater, but be careful: Transporting large quantities of old fuel or oil on our highways is restricted by law as to the mode of transport.  Throwing barrels of fuel in the back of an open truck doesn’t cut it as a “safe mode” of transport, and is a fineable offense if you’re caught — which isn’t much reward if you’re trying to do the right thing. It may mean delivering the bad fuel to the waste oil heater in smaller quantities, a bit at a time.
  • Consider fuel-polishing alternatives.