question about gas...

[bfan781]

Hi,
115 HP mariner outboard. I know there are a gazillion threads regarding winterization, but I am seeing mixed advice. If I have 20 or so gallons of gas left can I leave it over the winter or should it be drained? I treated the gas when it was added, if ok to leave it in the tank should i re-treat it? Also have a water separator..

 

[79Merc80]

Re: question about gas...

I have always been told to leave the fuel tank FULL and treated.

 

[wired247]

Re: question about gas...

Back when gas was just gasoline it was best to leave it full to prevent condensation. I buy 100% gas and leave my tank full in the winter but i have that option. Now that your gas is probably 10% ethanol ( or more ) you have at least 2 gallons of ethanol in that tank. The ethanol may phase separate out if it gets saturated with water after a few months. Then it drops to the bottom and does a great job of stripping the varnish out of your tank or it corrodes the tank. Then you start it up in the spring and all that crap sucks up into your motor.

I would drain it and use fresh gas in the spring .

 

[eavega]

Re: question about gas...

Do whatever feels best for you. Personally, I siphon out any gas I have left over during the season and use it in my vehicles. Its not so much a question of whether it will sour, or absorb water. Its more a question of 20 gallons of gas at $4 a gallon sitting there doing nothing, while I am paying additional money to put gas in my cars.

Rgds

 

[MH Hawker]

Re: question about gas...

To answer your question, yes you can leave it in your tank, some treat it and others don't, if it is only over a winter untreated is fine, but if it goes longer it may be at risk, who knows how busy you will be in the spring it may sit all summer and to the next year. Treating it is cheep insurance. I used to treat mine and leave it and never had a problem and I have had a boat sit for 2 years with out being used and it ran fine on what was left in the tank, but that way back before the E 10 days and 4.50 a gal prices.

But do run the carbs dry. the gas will evaporate and leave varnish behind. and that will plug them up next year. And fog your cylinders, over a winter it will sweat a bit and the moisture will cause pitting on the walls and accelerate ring wear. and of course change to LU oil and inspect for water.

I drain my tanks, I just find it a lot simpler to start off the next season with fresh gas and no worries. In my case I use pure gas but the E 10 stuff really dose cause a lot of problems. So why risk it. Drain it.

 

[oldman570]

Re: question about gas...

I also use straight gas and fill my tank and treat it with Stabile for storage. In the spring I use a electric fuel pump and hook it to the tank fuel fitting or hose and recurlate the fuel back to the tank just to mix any seperation from setting over time. This way any seperation setting in the bottom of the tank will get mixed back into the gas. A water seperator or fuel filter in the fuel line before the primer bulb will help catch any water or varnish that has formed from setting. Sometimes boats here in the north will set for up to 7 months before being used again. JMO
Oldman570

 

[rschap1]

Re: question about gas...

If you have fuel with ethanol in it, you have a spongue in your tank.
Ethanol absorbs moisture out of the atmosphere.
Condensation on the inside tank walls used to be the main concern and reason for storing full.
Now manufacturers recommend getting as much fuel out as possible, reduce the size of your spongue.
The ethanol pulls in water from the air in the tank, and seperates as staed earlier.
It is a heated and often debated subject, but that is my reasoning and Mercury along with the others tells their customers to get the old gas out if it includes ethanol.

 

[Bamaman1]

Re: question about gas...

Just treat the gasoline with an additive. Then, get your engine running (in water or on a muff) and disconnect the fuel lines to the engine. Let the engine run until the engine quits.

Then, enjoy your Fall and Winter. It'll be okay.

On the other side, if you have portable tanks, you can empty the fuel into your automobiles and come back in the Spring with fresh fuel.

 

[Chris1956]

Re: question about gas...

There is a lot of real sketchy advice here. Ethenol does not suck moisture out of the air. It does absorb water, "drying the gasoline", which is a good thing. Ethernol does seperate from gasoline, if enough water is in the tank. It will not mix back in. Oil will not seperate from the fuel either.

It really does not matter whether the tank is full or not. Since gasoline has dropped 50 cents/gal the last three days, I would leave it alone and bet on cheaper gas next spring. I do recommend you treat it. It is always a good idea to siphon a gal of fuel off the bottom of the tank in the spring. Check it for seperation or water, and reuse the good gasoline. Since your fuel is mixed with oil, you will clearly see the gasoilne/water boundary.

 

[wired247]

Re: question about gas...

The ethanol in E 10 does indeed pull water from the air and since all boat fuel tanks are directly vented to the atmosphere it can be a real problem when the water content gets over its saturation threshold of .5% . Alcohol and water are both polar solvents and will mix infinitely. Gasoline is non polar and mixes with ethanol until it reaches a saturation point. If water is introduced into the system and the saturation point gets met the alcohol phase separates and drops out with the water to the bottom of the tank where it can potentially dissolve varnish or corrode the gas tank. Aluminum and polar solvents don't play well together. Generally when you run through gas during the boating season its not a problem. If you are like me and live somewhere where it rains all winter long and doesnt get quite cold enough to freeze the water out of the air it can be quite humid and that vented gas tank will become a problem. If that is your situation also then an empty tank is better than a tank half full of 10% ethanol.

If you ever get really bored and want to know more about gasoline than you ever felt was prudent check this book out from the college library if you have one close.

http://www.bookfinder.com/dir/i/Automotive_Fuels_Reference_Book/1560915897/

Buying it at $100 might be a bit over the top.

 

[Chris1956]

Re: question about gas...

Ethanol does not actively pull moisture from the air. If water condenses in the fuel tank, the ethanol will absorb it, up to a point. After that saturation point is reached, the alcohol will no longer be soluable in gasoline. Bottom line: Ethanol will not cause more water to end up in the fuel tank over the winter, compared to regular gasoline.

 

[ondarvr]

Re: question about gas...

After 20+ years of using E10 I still use the same method, I turn off the key and put the boat in the shop. I may use it again in a month or maybe 6 months sometimes longer. I just took my carbs apart after 12 years and they were spotless. I make no effort to fill or drain the tank or carbs, just leave it as is when I get home.

I also just started up a couple of motors that hadn't been run in several years, one had a bad fuel pump when I stopped using it, it was still bad, changed it and it ran fine, so did the other one.

Locations that are new to E10 have far more problems due to the issues when converting it, locations that have been using it for decades report few problems.

 

[wired247]

Re: question about gas...

Ethanol does not actively pull moisture from the air. If water condenses in the fuel tank, the ethanol will absorb it, up to a point. After that saturation point is reached, the alcohol will no longer be soluable in gasoline. Bottom line: Ethanol will not cause more water to end up in the fuel tank over the winter, compared to regular gasoline.

Except that your bottom line is wrong. Ethanol is a polar hydrophillic solvent and will actively pull water out of the air even when the alcohol is suspended in gasoline. Since the alcohol never fully bonds with the base gasoline to form a true solution it is always in its near pure state except for the water it is bound with. The surface of the gasohol blend has ethanol ready and willing to pull water from the air. Pure gasoline does not absorb water and a tank full of pure gasoline may oxidize over the winter if left untreated but it will not collect water. Gasohol will absorb water from the air and if its in a humid area and can reach more than .5% of its volume saturated with water the alcohol will lose its loose bond with the non polar gasoline and will separate out and drop to the bottom of the tank where it can cause corrosion, and possibly dissolve very old varnish.

http://www.daremarina.com/custompage.asp?pg=joyner
http://www.daremarina.com/custompage.asp?pg=general_discussion
http://epa.gov/oms/regs/fuels/rfg/waterphs.pdf

Rains all winter long here. A boat left outside with a half tank of 10% gasohol is doomed to a spring of tank cleaning and carb rebuilding.

 

[ondarvr]

Re: question about gas...

Water that finds its way into the tank from condensation or other sources will still drop to the bottom of the tank (the “other” sources are the more common ones), small amounts of water will be absorbed by the ethanol be passed through the system with no issues. Larger amounts of water can cause problems with phase separation in E10, in E0 they build up until you run the tank down to a level where it gets sucked into the pickup tube and the motor either runs terrible or stops.

 

[Dave1027]

Re: question about gas...

I would drain it and use fresh gas in the spring .

That's what I do. I siphon it all out and use it in my lawn mower and truck. That way I'm using fresh gas next boating season. It's way too easy to siphon gas out with the aid of the primer bulb to get it started.

 

[Silvertip]

Re: question about gas...

Those of you who feel E10 fuel needs to be removed for winter storage are really wasting your time. Good grief we up here in the tundra have used E10 fuel for decades and if treated (or even untreated) will not go bad over a normal six month layup. If it did there would be a bunch of dead collector cars every year. It is simply not a problem. Treat the fuel, run the engine long enough to get the treatment through the fuel system and put the boat to bed. Stop creating problems where there aren't any.

 

[wired247]

Re: question about gas...

Stop creating problems where there aren't any.

Its more interesting living in places that have 100% humidity ( AKA Rain ) for 5 straight months out of the year.

 

[ondarvr]

Re: question about gas...

Its more interesting living in places that have 100% humidity ( AKA Rain ) for 5 straight months out of the year.

I live in that type of an area, and all I do is shut it down.