Bad gasoline

[teveau169]

Hi,
I live aboard a 1996 31’ Mainship Sedan Bridge powered by twin gasoline 350s. I blew my port engine while voyaging in the SW Gulf of Mexico last year. I eventually ended up being towed to my present berth in the Everglades.
Recently, I replaced the port engine. However, both of my gasoline tanks have sat without use or replenishment since last year or even longer ( I estimate some of the gas in either or both engines is over three years old).
The motor installers tell me my gasoline needs to be polished and possibly replaced.
What can be done to fix this problem?
BTW: none of the gas is ethanol.
Is there an additive I can buy and put into each gas tank to refreshen the gasoline or must I have it removed and replaced with fresh gasoline?
Please respond ASAP both to this forum and to me directly at tebeau169@gmail.com

[SVHarmonie]

Why do you not want to take the advice of your motor installers and polish the fuel? A reputable fuel polishing company will let you know if the fuel is usable.

No additive can "refresh" the gasoline if it is old and has begun to oxidize and "gum up".

[wsmurdoch]

In January 1990 Eastman Kodak sent me on an eighteen month temporary assignment from Tennessee to England. On the advice of the nearby Exxon gas station, I left my wife's Blazer on blocks in the garage with the tank completely filled with Exxon Supreme. The assignment ended up lasting almost five years. On our return the Blazer with a new battery started with a shot of ether but ran a little rough. The gasoline smelled like Varsol. When down to a half tank, I topped it back up diluting the old gasoline and never had another fuel problem. The Blazer had a GM 350 4 bbl engine. We sold it in 2017 with about 280,000 miles on the odometer.

[ggray]

Originally Posted by wsmurdoch

In January 1990 Eastman Kodak sent me on an eighteen month temporary assignment from Tennessee to England. On the advice of the nearby Exxon gas station, I left my wife's Blazer on blocks in the garage with the tank completely filled with Exxon Supreme. The assignment ended up lasting almost five years. On our return the Blazer with a new battery started with a shot of ether but ran a little rough. The gasoline smelled like Varsol. When down to a half tank, I topped it back up diluting the old gasoline and never had another fuel problem. The Blazer had a GM 350 4 bbl engine. We sold it in 2017 with about 280,000 miles on the odometer.

Not sure what type of gas OP has in his tanks, but possibly ethanol, which would be a different from what was in your tanks

[BlueH2Obound]

Originally Posted by ggray

Not sure what type of gas OP has in his tanks, but possibly ethanol, which would be a different from what was in your tanks

Did you even READ the post? OP clearly states "BTW: none of the gas is ethanol."

[tkeithlu]

The core issue to understand is that the volatile components of the gasoline have evaporated off. You can replace it with fresh volatile fuel, or add fresh fuel to it to bring it up to being reasonably useable. In temporate zones, winter fuel is likely to come with more volatility than summer fuel.

How much gas are you talking about, and how full are your tank(s)? You have several routes that don't involve hiring a polishing firm, depending on the situation.

If it's a small amount, and you have a way of disposing of it, toss it, including draining the carboretors. If it's more and you have space in the tank, mix in fresh, drain the carbs, and start over. If the tank is full of old stuff, you need to get rid of enough to mix in fresh.

Then, use it up.

For the future: if gas is going to set for long periods, pump it into your car after six months and use it up.

This problem plagued me in my small engines (genset, mower, small outboard), and plagues the Emergency Operations Center where I volunteer. Our answer is to always write the date of filling on gas cans with a Sharpie. Then, when six months rolls around, any sitting around goes into vehicles for immediate use. We store all motors with empty carboretors, and largely empty tanks, to avoid trying to start a chainsaw full of Varsol. Some small engines now come with purge buttons for this reason.

[rslifkin]

In general, I trust gas with stabilizer added for a year with no concerns (ethanol or not). Beyond a year, I start to worry a bit about octane loss. Lost volatility can be solved by either mixing in some fresh fuel or even a small-ish amount of liquid carb cleaner. In this situation, I'd at least want to have the fuel polishing guy take a look. Or take a sample of fuel from the tanks and see what you've got. If there's any concern at that point, either mix with fresh fuel or get the fuel disposed of and start fresh.

For small engines, I personally store with tanks full (and stabilized), partly to avoid condensation / rust in metal tanks. On the last run before storage, I shut the fuel off, wait a few seconds for it to burn off some of the fuel in the carb, then stall it out with a heavy blast of fogging oil (fogs the engine and also helps keep stuff from gumming up the carb). I just fired up the mower that hasn't run since early November and was put away with that treatment. Fired up just fine on the gas that was in the tank, blew a little smoke from the fogging oil and ran perfectly.

[ggray]

Originally Posted by BlueH2Obound

Did you even READ the post? OP clearly states "BTW: none of the gas is ethanol."

Well,I read most of the post!

But I missed that!

[tkeithlu]

Rslifkin, that's a really good procedure. I think I'll adopt it for the motors I know I'm not going to use for awhile. Thanks for sharing it.

[rslifkin]

Originally Posted by tkeithlu

Rslifkin, that's a really good procedure. I think I'll adopt it for the motors I know I'm not going to use for awhile. Thanks for sharing it.

No problem! To add to the small engine procedure, I add stabilizer to any fuel I buy for small engines. That way I don't have to worry much about how quickly I use it. Including time spent in stored equipment, I've never had a reason to use fuel more than a year old.

I also stabilize any fuel I put in the (gas powered) boat unless I know it's going to be burned within a few weeks. Never had a problem starting things up in the spring on fuel purchased the previous fall.