Fuel Tank Full or Empty -- Does it Matter?

henz73

Registered Member
City
Wilmington
I'm a new owner on the mid-Atlantic coast. I'd like to fill up the gas tank while the boat is on a trailer on the assumption that the price at a gas station will be lower than at a marina. I've had one person tell me to keep the tank low, and another suggest keeping it full. Aside from the weight of the fuel impacting operating economy, what other significant considerations are there, and what would you suggest that I do?
 
I always like to fill it up on the way to the launch area. That way I know I have the freshest gas available and I know I can use the 1/3 rule ( 1/3 out, 1/3 back and 1/3 to spare). Nothing sucks like running out of gas on the water. Also, remember that gas guages on boats are not as accurate as they are in our cars.

Tight lines.
 
Henz73, now for the reverse of cagrove.

It has been my practice, since the boat was new, to fill up the tank on the way home. Then when I get home, I can record the gas used, come actual to my Flo-Scan readings, and calculate how much Sta-Bil to add that night. Motor has never faltered, and sign of water in my Racor fuel / water separator. Personally, would rather carry the extra weight and keep my gas water free. I have been told that there is less chance of water forming with a full tank.

Please note, I am not saying that my way is the only way or best way, it just works for me.
 
Thanks for your feedback. I should have added that this boat will usually be in the water, not on a trailer. I will not typically have the opportunity to fill it up on the way to a launch area. Give this, for the initial launch of the year, should I fill it up?
 
Fill it up...there is no downside to having a full tank unless you're trying to set some kind of speed record in which case you're in the wrong boat anyway.

Tight lines.
 
There are really no special considerations for fuel level except during long-term storage. During these storage periods the traditional recommendation is to keep the tank either topped-off or practically empty. This was to prevent condensation from forming inside the tank and contaminating the fuel with water. There is another consideration when storing ethanol-blended fuels long-term and that is the Ethanol will separate out of solution with the gasoline and form an alcohol slug inside the tank that your engine won't like. It is ok to store ethanol-blended fuels up to 3 months with the use of additives such as Star-Tron and Stabil. There is not sufficient testing data to know how such fuels will react beyond 3-months. It is generally recommended if storing a boat that uses ethanol-blended fuels longer than 3-months to empty the fuel tank as much as practile (via a siphon or similar device) and refill on first use after storage. Hope this Helps.
 
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