Ethanol: 10% is added to our fuel to save oil. The problem is it can cause serious problem to boat motors. Studies now show that it is causing problems in cars as well . Now they may change to 15% in many states. Here is information you NEED to know.
Our boat motors were designed in the 80,s to burn ethanol and most fuel lines and rubber parts have been converted , so no problem to the motor in most cases. Now the bad news.
Ethanol sucks water out of the air, through your tank vent system. As it sits in the tank in it makes its own water. Since our tanks sit still for much of the time this water settles out to the bottom. Also tiny bits of debris and dust stick to the walls of your tank sealed in by the varnish left from gasoline. Ethanol "washes " the tank sides like paint thinner causing debris to settle to bottom. When you run your motor this crud gets sucked into the fuel system. Carbureated motors are not so bad, we clean and rebuild the carbs flush the lines and you are on your way. Those of you with HPDI, fuel injection, fitcht and optimax have greater problems. This stuff plugs injectors, ruins high press. fuel pumps, vapor tanks etc. Repairs can be way more expensive.
Old stale gas is also a big problem. The fuel will lose 5 to 10% of the octane each month it sits.Low octane causes pre-ignition or "spark knock". Your motor will burn pistons out in seconds with bad gas.
Avoid these problems by:
2. add fuel conditioner every time you add gas. Each manufacturer claims to have the best, make your own choice. Any kind is better than no kind.
3. Use the boat more or at least agitate the fuel tank(move boat around) often to keep the particles in suspension.
4. periodic adding octane boosters will in crease performance and reduce fuel consumption.
5. change the fuel filters on the motor often in addition to the canister filter you need to install.
The best advice I can give is uses the boat often and try not to buy ethanol.