There has been much written about boat maintenance, and most of it is good advice. For me, owning two guide services that each use different boats, boat and trailer maintenance is a must. I’ll turn this into a 3-part entry, beginning with the boat’s fuel.
With the new government fuel regulations, ethanol is here, and here to stay. Like it or not, we have to deal it, and deal with its consequences, which are very real. I always make sure to use a fuel treatment specifically made for ethanol. While there are several products on the market, I have always used Stabil. The one that is made to help treat ethanol in gasoline is blue, different from the red that Stabil always has been.
For winter storage, this will help prevent phase separation. The long and short of it is that if there is phase separation, we have a classic oil and water scenario to deal with. Phase separation occurs when the water that is present in the fuel (and ethanol carries with it a guaranteed high percentage of water) separates from the gasoline. If this happens, the water will sink to the bottom of the fuel tank, with the gasoline floating on top, hence the oil and water scenario. What happens next, if not detected, is that when the boat motor is fired up, the first liquid that is sucked into the engine is the water sitting on the bottom of the fuel tank. If this were to happen, it is now certainly an expensive visit to the marine mechanic.
After adding the correct amount of Stabil to my fuel tank, I always make sure to top off the tank. There is conflicting information about whether or not to top off or not, but most mechanics will agree that an empty tank left for any length of time will leave room for condensation from the ambient humidity of the air. Condensation, just as the water in the ethanol is bad news. Once the tank is topped off, I always make sure to run the outboard for a while to ensure that the Stabil is run into all of the fuel lines leading into and in the motor itself.
Outboard engine manufacturers recommend installing a second water fuel filter, which will help if there is a small amount of phase separation. This is something that I have also installed, but hopefully I can avoid this phase separation altogether.