Fuel Contamination with Water
Posted: Mon Jun 09, 2025 9:37 pm
Recently, the 225-HP [Yamaha-made Mercury-branded] four-stroke-power-cycle engine failed to start on my 2005 210 Outrage after the boat had not been used for more than a year.
I removed the cowling and observed the red ring that indicates water in the fuel filter was floating at the top. I removed the filter bowl and dumped the contents into a jar. The liquid smelled more like water than gasoline so I pumped some more with the bulb and filled the jar. It was not encouraging.
My main concern was for the engine. I don't want and don’t need and can’t afford a new engine.
I bought a new hose and primer bulb assembly, and I connected new, clean fuel from a 5-gallon can to the engine, but the engine did not start.
I opened the drain on the fuel-vapor separating filter. The fuel that flowed out was white and creamy. I continued to force more clean fuel into the engine and finally got it to run smoothly on a hose adaptor in the driveway. See Figure 1 below.
The next day I bought a plastic barrel from a feed store and began the process of draining the fuel tank. I extended the fuel line from the tank though the engine splash well drain and filled a Mason jar. See Figure 2 below.
I then decided to completely drain all fuel--about 30 to 40-gallons--from the fuel tank. Gravity-draining was not possible. I used a small AG-sprayer 12-Volt pump that specifically said to NOT use for flammable liquids. It was a plastic pump so the dangers were sparks and the plastic disintegrating while pumping. Neither happened, and I drained the tank efficiently. I suspect that waterlogged gasoline vapors would not pose the same threat as fresh gasoline, and it was a breezy hot day.
While I was watching the tank empty I decided to remove the RACOR fuel-water separator filter and check it out. I did not take any photos of the filter but it was rusty as can be. I did drain the fluid inside the filter and I use the term fluid lightly. See Figure 3 below.
I cleaned the filter assembly, replaced the canister and put it back in the boat.
I suspected that the water in gasoline might have come from several places.
The fuel (as delivered by the fuel vendor) may have contained water; many on-water fuel vendors can pump fuel with some water. I do not think this is my source, as the boat fuel tank developed water without being re-fueled or being used much.
The other possible sources might be the fuel fill fitting on the gunwale, the hoses for fill and feed, and the seal of the tank level sensor.
A worst case cause of water in the fuel wouldbe is a crack in the plastic fuel tank.
I am ordering a new fill fitting, new hoses, and will replace them all. The boat is 20-years-old and due for some new fuel lines.
CAUTION
Boston Whaler recommends marine-grade fuel hose and double stainless steel clamps everywhere. The hose is either rated type A1 (rated for continuous contact with fuel) or A2 (fuel vent or vapor hose). Ordinary automotive hose is not a good solution and should only be used as a temporary solution. I will continue the narrative describing the process of replacing the hoses in my boat. It should be entertaining for all but myself.
[Moderator's note: I added figure numbers and captions to the illustrations. These can be emended by the author if necessary.]
I removed the cowling and observed the red ring that indicates water in the fuel filter was floating at the top. I removed the filter bowl and dumped the contents into a jar. The liquid smelled more like water than gasoline so I pumped some more with the bulb and filled the jar. It was not encouraging.
My main concern was for the engine. I don't want and don’t need and can’t afford a new engine.
I bought a new hose and primer bulb assembly, and I connected new, clean fuel from a 5-gallon can to the engine, but the engine did not start.
I opened the drain on the fuel-vapor separating filter. The fuel that flowed out was white and creamy. I continued to force more clean fuel into the engine and finally got it to run smoothly on a hose adaptor in the driveway. See Figure 1 below.
The next day I bought a plastic barrel from a feed store and began the process of draining the fuel tank. I extended the fuel line from the tank though the engine splash well drain and filled a Mason jar. See Figure 2 below.
I then decided to completely drain all fuel--about 30 to 40-gallons--from the fuel tank. Gravity-draining was not possible. I used a small AG-sprayer 12-Volt pump that specifically said to NOT use for flammable liquids. It was a plastic pump so the dangers were sparks and the plastic disintegrating while pumping. Neither happened, and I drained the tank efficiently. I suspect that waterlogged gasoline vapors would not pose the same threat as fresh gasoline, and it was a breezy hot day.
While I was watching the tank empty I decided to remove the RACOR fuel-water separator filter and check it out. I did not take any photos of the filter but it was rusty as can be. I did drain the fluid inside the filter and I use the term fluid lightly. See Figure 3 below.
I cleaned the filter assembly, replaced the canister and put it back in the boat.
I suspected that the water in gasoline might have come from several places.
The fuel (as delivered by the fuel vendor) may have contained water; many on-water fuel vendors can pump fuel with some water. I do not think this is my source, as the boat fuel tank developed water without being re-fueled or being used much.
The other possible sources might be the fuel fill fitting on the gunwale, the hoses for fill and feed, and the seal of the tank level sensor.
A worst case cause of water in the fuel wouldbe is a crack in the plastic fuel tank.
I am ordering a new fill fitting, new hoses, and will replace them all. The boat is 20-years-old and due for some new fuel lines.
CAUTION
Boston Whaler recommends marine-grade fuel hose and double stainless steel clamps everywhere. The hose is either rated type A1 (rated for continuous contact with fuel) or A2 (fuel vent or vapor hose). Ordinary automotive hose is not a good solution and should only be used as a temporary solution. I will continue the narrative describing the process of replacing the hoses in my boat. It should be entertaining for all but myself.
[Moderator's note: I added figure numbers and captions to the illustrations. These can be emended by the author if necessary.]