Old Gas and Tank Condensation - Need Help!

[Jesse]

Why not polish the fuel? If there is enough capacity in one of the tanks to accept the fuel in the other tank too it could be done without removing any fuel from the boat and it would save having to replace the fuel. If there isn't a service locally making your own polisher isn't difficult and they are a handy thing to have

[Dean Paul]

Consider adding fuel additive PHASER 3000. A little pricey but worth the peace of mind especially if you have galvanized fuel tanks. It is supposed to emulsify and integrate any water in fuel back into fuel components. Check their website for info. Company name is Primrose. Also consider Startron as an additive for ethanol fuel.

[skipper53]

If you can access the tank directly, you can use a cheap siphon pmp.ket and draw a fuel sample from the,lowest point of the tank. Draw the furl.from the tank in a jerry can or small portable gas can. If there is a small.amount of water, add Seafoam. If the sample doesn't smell.like varnish, pump in fresh fuel and run it. If it does smell like varnish, siphon it out and get it to Safety Kleen or similar for disposal.

[Jackz]

Seafoam

[Lake-Effect]

I'm a clean-gas zealot. I only buy ethanol-free gas for the outboard, and at the end of the season I dump any remaining boat gas, with 2-stroke oil or not, into my truck, and start with fresh gas in the spring.

You say the tanks were sealed... but all such tanks have to have vents, yes? So it was still exposed, volatiles could evaporate off, it's gonna separate, etc etc. I'll leave it to an expert to answer, but my guess is that after two years, it would be separated and pretty inferior gas.

If water condensation and accumulation at the bottom was the main issue, you could simply open the fuel line before any filters and pull out a few gallons from each tank, which should get the majority of water and gunk out of each tank. You could then dump in some methyl hydrate into each tank which should pick up any remaining water.

But before doing all that, I'd want an expert opinion on whether two year old gas is worth keeping and using.

I love me some Seafoam too, but I don't know if even that would salvage such old gas.

[Cheechako]

Can you hand pump a sample out of the fuel gauge fitting or does the tank have a clean out etc opening on the top? Use a tube down to the bottom of the tank. I assume your fuel pickup is on the top of the tank. That's been code for many years now.

Not a fan of gas that old for sure, yours is not alcohol gas?

I'd worry about trying to polish/filter it clean. One static electricity spark and.....

Once you determine water is not an issue, maybe you could transfer one tank to the other and put new fresh gas in one tank. Then gradually use fresh and old mixed. Two 318's will burn it pretty fast. But yours are too full?

Add a water separator filter. Then run the engines a lot to burn gas, then add good fresh non alcohol gas...?
If non alcohol gas I would be tempted to go for it with good filters.

[jharding]

wow, I wouldn't be worried about 2.5 year old non ethanol gas in the least, I have gotten running many old cars and motorcycles with ten year old gas and they ran just fine. checking for water in the bottom is a good idea or just pump out a gallon and see what is there, even if it smells like varnish it will burn in that 318.

[rotaxmax]

You have a range of good answers, but if it were me, I would siphon a sample out of the bottom of the tanks, and see if you get water and/or rust particles. If so, siphon it out until you get clean gasoline. Then just run it, and change/check your spin-on filter/separator several times in the next few miles. I've had this issue in the Bahamas several times with boats stored for years, and I would just run a few miles after siphoning the water out of the bottom of the tank, and check the filter by spinning it off and pouring out the contents in a clear vessel to check the presence of water or dirt. Once it's gone, put in a new filter and resume life as usual. You need to run it on the water though, to shake up the tanks and get it all out (if it exists).

As a side note, gasoline is an effective fuel for a very long time, although maybe not optimal (remember: the perfect is the enemy of the good). I used to cache fuel in northern Canada for years at a time for my float plane. When I had more than I could use, I would leave it on the tundra in a steel barrel elevated above the bare ground several inches on rocks, knowing i would probably not be back there for a year or more. One to three years later, after checking for water and rust, I would pump it in my Cessna 180 and go. Never had a problem. This was true with both Avgas and no-ethanol gas. Never had experience with 87 octane 10 percent ethanol gas.

All that being said, I once stored a steel drum of 108 octane race gas that, after a year of storage, developed globs of a yellow oily substance that clogged the carburetor of my snowmobile very quickly. After two cleanings of the carb I looked into the drum with a flashlight and determined that there was no saving that fuel. It was used over the next couple years as 5% dilution of the oil in my cabin's gravity-feed oil furnace. I'm no chemist or engineer. I won't offer my armchair opinion based on reading other forums or YouTube, but I will offer my actual experience over several years of surviving gasoline powered vehicles in sometimes remote places that required using old gas. Your experience may differ.

[NorthCoastJoe]

I would just put a Racor filter in line and go with it. No smog on your 318s, it should be no problem.

https://www.racorstore.com/index.php...IaAky0EALw_wcB

[RaymondR]

Put some in a clean drinking water glass and put it out in the sun to evaporate. If there are no residues left in the glass when it's all evaporated it's going to burn in your engine without causing any harm. Whether or not the engine produces full power depends on which volatile portion has evaporated but my guess is that if you dilute it with fresh gas you won't notice any difference.

The thing about all crude oil derived hydrocarbons is that they are already all millions of years old when you put them in your tank.

Many old farm tractors were run on kerosene, a low volatility fuel. They had 2 fuel tanks, one for gasoline and one for kerosene. You started them up on gasoline and warmed them up then switched to kerosene. A cold engine would not run on kerosene because it was not volatile enough to vaporize and for an explosive gas/air mixture to form. By heating the engine up before switching to kerosene you provided enough heat to evaporate the kerosene on it's way into the combustion chamber allowing it to properly mix with the air to form a combustible vapour which the spark plug could subsequently ignite.

Provided there are no solids in your gasoline which will not burn you have a similar situation with a tank full of gas from which too many of the volatiles have evaporated. Mixing new, and consequently volatile gas, with the old will allow the mixture to vaporize and properly mix with air and the engine should run.

[RustyBullets]

Thanks to all...your comments confirmed my initial instincts, which gave me the "teddy bear" comfort zone. I did the smartest thing first, and got VERY lucky: I used local media (Facebook for our town) to find a good mechanic, and when I did, I felt like I fell out of the manure truck into the rose garden: First call was from (and to!) a 50 year Chrysler 318 marine engine vet, who got into my transom as if he was sitting down with an old friend. Sort of closed his eyes, grabbed a screwdriver (by instinct) from his bag, put it on one electrical connetion, then a carb adjustment, and kind of gave a gentle moan as he turned did so. Pulled a few ounces of gas from the lines, and saw no H2O, and had a nice sniff of good gas. 30 minutes later the Lady Jake gave a few "thrumps!" and settled down to a gentle purring sound. He gave it a few pats. Next week, we check the other engine. I'm a happy man.

And thanks to all of you. Moral of the story: Ask for advice, listen to it, and have a first rate mechanic on tap!

[Lake-Effect]

Thanks for reporting back, and I'm happy that you got good news.

I will in future be a bit less prejudicial about old gas, thanks to this thread.