Pontoon Boat & Deck Boat Forum

I have a little bit of really old fuel (maybe a 1/2 gallon) in my boat that I can't seem to get pumped out and my tank doesn't have a drain. If I add new fuel, will it dilute the old fuel and be OK to use or will the old fuel mess up the new stuff? I had switched to a smaller tank so I haven't used this tank for about three months so what little bit of fuel that hasen't evaporated is probably pretty bad. Now I want to go back to the original tank.

If I were you, I would add SeaFoam at above the recommended rate, which is one ounce per gallon. I wouldn't add too much new gas so that maybe you can run it until all the old fuel is used up.
I'm sure that situation exists for many boat users. I think in my case that I have a 56 gallon tank in my toon and I know there's gas in there from one year to the next. Same thing for my bass boat, which has a 45 gallon tank.
Here's my procedure: If I'm buying gas on land, I add Mercury's KwikCare which is supposed to neutralize the ethanol. I use one ounce per 10 gallons of fuel. I use SeaFoam at the end of the season and run the motor until I'm sure it's had a chance to get through the system.
I've been using SeaFoam for more than 10 years as my storage additive. I have never had an issue with phase separation of the ethanol.
Here at Lake of the Ozarks all marine fuel is ethanol free.

I wouldn't worry about a little but of three month old fuel. Fill err up and run it. Ezpz.

Ron Burgundy wrote:I wouldn't worry about a little but of three month old fuel. Fill err up and run it. Ezpz.

Thanks Ron. Havent heard from you in a while. Glad to see you're still floatin! I'm in the process of selling my 20'r and looking for a 24 to 30' toon. Maybe use my coast guard license and run some charters over here.

Butch

Ron Burgundy wrote:I wouldn't worry about a little but of three month old fuel. Fill err up and run it. Ezpz.

This, it isn't enough to to worry about from your friendly petroleum tech.

Yep, it's just fine, enjoy, don't worry

FWIW: For 11 years, I had twin 200 Yami EFI's with a 200 gallon tank. The mix in the tank was probably more old gas than new gas. Any additives were haphazard. We never had engine problems related to fuel.

Here's a good example of why I run Sea Foam all season and just add extra at storage.

you should be fine.. I hope so because I have the same situation, only "more" old fuel.... my boat had approx. 1/2 tank ( 12 gallons or so ) left from last year. Fortunately it is ethanol free and I added a good stabilizer to it at the time of fill up... just last week topped off the tank with more ethanol free fuel, added a can of seafoam and more stabilizer.... haven't had it to the lake yet but fired right up in the driveway on muffs.