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Old 03-05-2020, 17:55   #1
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Old Gas and Tank Condensation - Need Help!

Folks:

I have a serious problem needing your advice involving old gasoline in my tanks.

My 34' Pequod Sport Fish ("Lady Jake") just came off 2-1/2 years on the hard. I have about 50 gals of ethanol-free marine gas in each of two 100-gallong steel tanks, feeding my 2 Chrysler 318 engines, each mounting a 4-barrel carburetor. The fuel tanks have not been opened since gas was put in, just before it went on the hard. (Don't ask...long story.) They were fueled here in Oriental, NC, where the humidity probably was in the 70% level at the time or possibly more.

I have not started Lady Jake since going back in the water 2 months ago, nor have I opened the fuel tanks. I am at the stage where I am ready to start her up. I have two principal concerns: (1) The age of the gasoline which should not have degraded the way ethanol gas does, but which I know can degrade in other ways. (2) Whether there is risk of any appreciable condensation in the air in the tanks, resulting in condensate water going to the bottom of the tanks.

Just before going on the hard, I replaced/rebuilt both carbs, since the prior owner had filthi-fied them with ethanol gas. I don't want to go through that again. So I am leery of taking chances.

I am considering putting high-detergent fuel additives in the tanks and/or adding new marine gas to minimize varnish problems. If this makes sense, I don't know how much to add.

I am also considering having a competent engine tech draining the fuel lines at the filters to drain any water that has settled. There aren't a lot of old-timey engine techs around here, though.

I've also considered having the tanks pumped out and just starting from scratch, including draining the lines at the filters. Not a lot of people want free gas (can't be siphoned - boat is in water now and tanks are below waterline) and I can't even seem to find a commercial pump-out company for gasoline.

OK, folks: Any advice is appreciated. Good advice is even more so. Thanks!

- Rusty
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Old 03-05-2020, 18:01   #2
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Re: Old Gas and Tank Condensation - Need Help!

Pull a sample of fuel and see what you get. If there's no obvious water or other quality issues, see if an engine will run on it. I'd mix in some fresh gas if possible to get octane back up and help make up some of the lost volatiles.
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Old 03-05-2020, 18:21   #3
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Re: Old Gas and Tank Condensation - Need Help!

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Originally Posted by rslifkin View Post
Pull a sample of fuel and see what you get. If there's no obvious water or other quality issues, see if an engine will run on it. I'd mix in some fresh gas if possible to get octane back up and help make up some of the lost volatiles.
What is your opinion on the chances of condensation at the bottom of the tanks?
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Old 03-05-2020, 18:27   #4
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Re: Old Gas and Tank Condensation - Need Help!

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Originally Posted by RustyBullets View Post
What is your opinion on the chances of condensation at the bottom of the tanks?

With the tanks partially full, it's definitely a risk. But the fuel is non-ethanol, so you should just be able to stick a hose into the tank and pull some fuel from the bottom to confirm no water (or to remove any water that's in there). Easy fix, unlike ethanol fuel where water is absorbed harmlessly until you hit the limit for how much it can absorb, then it separates and you have lower octane junk fuel and separated water / alcohol mix left.
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Old 03-05-2020, 19:18   #5
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Re: Old Gas and Tank Condensation - Need Help!

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Originally Posted by rslifkin View Post
With the tanks partially full, it's definitely a risk. But the fuel is non-ethanol, so you should just be able to stick a hose into the tank and pull some fuel from the bottom to confirm no water (or to remove any water that's in there). Easy fix, unlike ethanol fuel where water is absorbed harmlessly until you hit the limit for how much it can absorb, then it separates and you have lower octane junk fuel and separated water / alcohol mix left.
Tank is about 3-4' below deck filler. Not sure how to get a sample out. Still leaning hard to draining at the filters, which will also get me a gas sample to examine. Would you add "fresh" fuel? I probably have 50 gal of space for a 1:1 proportion. But hauling 100 gallon from my drive, down a dozen steps, pouring slowly in, 5 gal at a time, is gonna be a pain.

And would you add detergents to the fuel to prevent varnish?

Thanks again,

Rusty
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Old 03-05-2020, 19:40   #6
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Re: Old Gas and Tank Condensation - Need Help!

I was thinking of a tube down the filler and a gas safe pump to draw some fuel out. How worried I'd be and how much fresh fuel I'd add would depend on what the sample looked like.
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Old 03-05-2020, 23:02   #7
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Re: Old Gas and Tank Condensation - Need Help!

12 V electric lift pumps from an auto parts store are fairly cheap and connected to the fuel line from the tanks would probably pump them out into a fuel drum(s) fairly quickly.
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Old 03-05-2020, 23:08   #8
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Re: Old Gas and Tank Condensation - Need Help!

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12 V electric lift pumps from an auto parts store are fairly cheap and connected to the fuel line from the tanks would probably pump them out into a fuel drum(s) fairly quickly.
Thanks...but the problem is that I've got a total of 80-100 gal, in the tanks. Finger pier is below grade about 15', so then it's up steps, so a drum doesn't work; has to be gas cans. Then 100' to my drive way. Even then, what do I do with the drum? Yeesh. I know.

Thanks again...rusty
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Old 04-05-2020, 02:18   #9
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Re: Old Gas and Tank Condensation - Need Help!

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Thanks...but the problem is that I've got a total of 80-100 gal, in the tanks. Finger pier is below grade about 15', so then it's up steps, so a drum doesn't work; has to be gas cans. Then 100' to my drive way. Even then, what do I do with the drum? Yeesh. I know.

Thanks again...rusty
You need to pump out the bottoms from the tanks into a container to check for water and rust and sludge. If there is none I would just dilute what's in the tanks with fresh gas and burn the fuel in the tanks running the engine. I'd probably try for at least a 1 to 1 mix.

I have refueled my boat by rolling 44 gallon drums down the beach and towing them out to my boat with my dingy then pumping the fuel into the boat tank with the drum floating upright in the water.
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Old 04-05-2020, 03:29   #10
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Re: Old Gas and Tank Condensation - Need Help!

Greetings and welcome aboard the CF, Rusty.
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Old 04-05-2020, 05:25   #11
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Re: Old Gas and Tank Condensation - Need Help!

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Originally Posted by RustyBullets View Post
Thanks...but the problem is that I've got a total of 80-100 gal, in the tanks. Finger pier is below grade about 15', so then it's up steps, so a drum doesn't work; has to be gas cans. Then 100' to my drive way. Even then, what do I do with the drum? Yeesh. I know.

Thanks again...rusty

I'd take a pair of gas cans and pull a few gallons out of each tank to start. If you get clean gas out or a little water and crud followed by clean gas, then there's no need to worry about pumping the rest out and transporting it. Just add some fresh fuel and see how everything runs.
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Old 04-05-2020, 06:10   #12
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Re: Old Gas and Tank Condensation - Need Help!

Tank condensation doesn’t happen much at all, the water comes from moist air being taken in and the fuel absorbing it, then when temp drops it comes out of suspension, if you have water in your fuel it’s most likely coming from a leaking fuel cap and rain.

But take your oil change pump and use it to suck out the bottom of the tanks and if it comes up clean look at the fuel, it won’t even smell right, and won’t even have the right color, maybe take a gallon and run it in your lawnmower or something as a test.
A carb is an easy thing to clean if you get to to that point, but I’d top the tanks off with fresh fuel and burn it, I’d also most likely put a bottle of sea foam in each tank as sea foam does relay seem to clean, and or Techron, it also is a strong detergent.
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Old 04-05-2020, 08:50   #13
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Re: Old Gas and Tank Condensation - Need Help!

I might also smell the fuel in each tank. Since you have NON-ethanol gasoline, if it smells like varnish, it is varnish, and will immediately stick and clog in the carburetors. It will need to be removed and replaced. Don’t ask me how I know.
Ethanol fuel holds and attracts moisture, but when it gets old does not smell like varnish. It holds the water in suspension as opposed to letting it stratify and settle out at the bottom of the tank. Gas-line anti-freeze, (which is a mixture of isopropyl and methanol), works similar, and could be added for the initial startup and use. Use all of this fuel and “fill” your tanks with pure gasoline with Sta-Bil fuel stabilizer, and you should get several years from it. Make sure the tanks are quite full, it is the space above the fuel where condensation occurs inside a fuel tank.
One more thing you might try. “Water indicating paste”. Put some on a dipstick and it will show you if you have stratified water in the bottom of your tank.
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Old 04-05-2020, 09:06   #14
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Re: Old Gas and Tank Condensation - Need Help!

That gas is too old to mess with IMHO. Shelf life of gas is measured in months, not years. 2.5 years on the hard and how long before that was that gas purchased?

Pump it out into 5 gallon or whatever weight you can manage and take it to a hazardous waste facility for disposal. Start with clean, new gas. I'd also flush the fuel lines to the carbs as well. Depending on difficulty of access and age it may be easier and wiser to replace the fuel lines. Fuel hose is cheap.
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Old 04-05-2020, 09:17   #15
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Re: Old Gas and Tank Condensation - Need Help!

Rusty:


First you need to determine if the gas has turned to varnish. Obtain an automotive electrical (12-v) fuel pump. Drop a hose into the tank through the filler neck and suck-up some of the gas. Alternate is to attach the pump to your fuel line and suck out a small amount. Third would be to access the tank gauge sending unit and remove. If it smells like varnish, you will need to find someone to empty the tanks as it will not burn.


If it smells like gasoline, install a good fuel filter/water separator (Racor, etc) - maybe start with the finer 3 micron. Add octane booster and run the engines. Check the water separators after a while to see what the filter has blocked and if any water has separated out. Buy more filters and run the boat.
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