Storing boats with a full tank + stabilizer

[herminator]

What do others do when storing their boats/motors during the winter months? The book says to store the boat with a full fuel tank and use stabilizer. After storage and in the spring (2 experiences), the motor really runs rough until that tank of gas is used up. After fresh fuel is added, no problems. Do any of you store your tanks completely empty after running the carb clear of gas? Thanks for your replies.

[Dave B]

The problem with storing the boat with anything less than a full tank is that moisture develops in the void space. Continued changes in temperature over the winter will cause LOTS of water to be deposited in the gas. When they say store your boat with the tank full, it should be as absolutely full up to the top as possible. Storing with an empty tank would mean lots more void space and therefore (I guess) lots more water. Plus, if you had no gas in the system, started to collect water in small lines and small spaces, you could have problems with freezing.

Stabilizer helps the gas retain it's octane rating. My dad says this is only a problem now that we have to use unleaded gas. Apparently, leaded gas "kept" much better.

All that being said, I know what you mean. My boat runs poorly until that first tank is used up.

Dream situation? Heated storage.

[Airwave(OH)]

You should NOT store your boat with a full tank. Store it with very little gas. Stabilizer reduces the octane level. If you have a full tank you'll have to use some before you can get the octane back up to snuff. If you leave room you can fill your tank with HIGH octane in the spring and bring the octane level back up where it should be. You should not run the motor on octane real low. If your getting moisture in your tank you have something else wrong. The big moisture problem that started most rumors of storing with a full tank started back when Steel tank were common. Not much of an issue anymore.

[Airwave(OH)]

There isn't anything here TRUE ^^^^^^^^^^

[IaCraig]

I always make sure tank is below 1/2 for the winter, then top it off with fresh high octane 1st thing in the spring before I start it. I've never had a problem. And my garage is not heated, but it is attached to the house and never gets below freezing.

This may be a bad approach, but you asked what we did, not what the manufacturers recommend.

IaCraig

[mnjimcarp]

is this the LTV herminator?

[What??]

Just how does fuel stabilizer reduce octane?? I find that hard to believe from a chemistry standpoint. Me thinks you've been hanging out around the gas pump too long.

[Hans]

"Running the carbs dry" can cause ugly problems on some oil-injection 2-strokers!

I always store my boat with a full tank of gas, treated with Stabile and Sea Foam, and fog the engine. This avoids all fuel system contamination problems, and I've never yet had one fail to start in the spring.

Hans
--

[Dave in Mpls]

I store my boat with the fuel tank (41 gallons) full. During the boating season, I add 1 can of Sea Foam per 20 gallons of fuel. When I top it off for storage, I add enough to keep the 1 can/20 gallon ratio, plus add 1 extra can to the tank, to bring it up to approximately 1 can per 14 gallons. I've yet to have a problem come spring.

Different strokes for different folks, I guess. I do agree with the "What??" post, in that I don't believe stabilizer will reduce the octane in the fuel. Where is our resident expert Kip when we need him?

Regards

[Bo]

There's alot of different thoughts here. But a very good technician friend of mine told me to leave aprroximately 1/4 tank of fuel in my boat because even if the fuel is stabilized it can drop its octane level. If you have oil injection, you should drop a little 2 cycle oil into the tank because when you first start the engine in the spring, it takes a little time before your oil pump starts working to make the oil injection work. This can cause predentination(sorry, not sure that's spelled right)and can score your cylinders. Let motor run for a while in your driveway and then take it to your local filling station and put in fresh gas and you should be all set. Just some thoughts from an old friend.

[MedicineMan]

Just another thought regarding storing gasoline for long periods
of time. According to my Husqvarna lawn tractor manual, storing
alcohol blended gas for long periods of time is not good. It
"attracts moisture which leads to separation and formation of
acids during storage. Acidic gas can damage the fuel system of
an engine while in storage". I only use gasahol in my car where
it is required by law in MN, never in any other engine.

[Phil T.]

I store mine full, and add a can of SeaFoam to the tank when I take it out of storage. The main engine runs okay (it's a four-stroke), until I've run off about 1/4 tank and refilled with fresh gas. Then it runs good. The 2-stroke kicker needs fresh gas any time of year to run well.
The owner of the storage building really wants everyone's
tanks full. Should a fire start, there would be only fire. A single tank full of only fumes would explode and could take several houses/businesses with it.

[KevinA]

Not to rattle your chain & the guy that owns the building can demand anything he wants, but the explosion resulting from a 40-60 gallon tank full of fumes, a tank that is installed in the floor of a boat, that is surrounded by lots of other boats, that are all surrounded by a building...won't have enough energy to take out neighboring houses & businesses. Things 'explode' because the contents are looking for much greater volume VERY quickly. The act of tearing open a gas tank, busting the floor boards out of the boat, filling the volume of the building & blowing it apart & then taking out neighboring buildings would consume a bit more energy than 40 "gallons" of gas vapor would contain. I would think a building with say 50-100 boats in it, all full of fuel, would be the real thing firemen would worry about & the real danger to neighbors...whether one or two with partial tanks popped now & then would be a minor concern. It slays me that "some guy" with an empty building to rent is always referred to an expert...simply because he owns a building. Fill a HOUSE with natural gas & have the furnace kick in...now you have enough potential energy to take out a building & at least do some damage to the neighbors...we all see it on the news occasionally.

Over-winter the boat with a ~1/4 tank or less, stabilize it, don't run the motor dry, fill it up with fresh gas in the spring & have fun. The condensation thing is a leftover from guys storing their boats in the water (i.e. a foot or two above water where the humidity stays quite high). Gasohol will attract water from the air without it having to condense...this is why a 3/4 tank of fresh gas will help (along with some octane) as this will greatly dilute any moisture that was absorbed. The idea of gasohol continually sucking up moisture from the air & depositing it as liquid water on the bottom of the tank, all winter long, isn't going to happen. There has to be a driving force (chemical potential imbalance) for this moisture vapor-to-liquid-water "engine" to work...once the gasohol is saturated with water (i.e. the water and gas will exist in a one phase liquid) no more water will enter the gas (other than to replace the water that is leaving it = an equilibrium).

[Sparky]

Boy, a lot of excitement about fuel tanks. I fill mine half way, add the appropriate amount of Stabil, and then top the tank off. I've been storing my current boat this way for 9 seasons. It fires right up in the spring and runs fine. It's interesting to hear all of the different ways that people get their boats ready for storage. I guess it's like fishing, do what works for you. If it doesn't work very well try something else.

Sparky

[Airwave(OH)]

Another thing is why would you want to store X amount of fuel. Why wouldn't you want to start out in the spring with nice fresh stuff. I have had gas that was sitting in a can for the lawn mower that you could not lite with a match. This should tell you something. The stabilizer does reduce octane and helps remove corrosive contaminates. Yes I know "I've done it for years with no problems" I hear it all the time, but I also fix them when it doesn't work out all the time.. You decide I get 55 bucks an hour..Stabilize and Fog !!!!!!

[MedicineMan]

One-fourth cup of gas fumes has the explosive power of one stick
of dynamite.

[Herminator]

Airwave's response is precisely why I asked the question in the first place. Some do this, others do that. Which side of your pants do you keep your johnson? The manufacturer (Mercury, 75 hp. 2 stroke) says to store the tank full with stabilizer. Fine. But I get poor performance until the first tank is used up. My solution this year will be to siphon my stabilized boat fuel to my winter beater car and start with fresh fuel in the boat. Thanks for all of your comments even though, all together, I have about 6 solutions to my problem from your recommendations. Where are the motor manufacturers when you need them! Any Merc engineers out there?

[Dbl]

I have always just filled to about 1/4 full and then used Sea Foam or Stabil, fogged etc. and have never had a problem with water in the gas. Motor runs great in the spring with the addition of fresh gas. Different strokes for different folks. This debate will never end.

[rob]

i would think if one stores their boat for 6 months or longer then the fuel could detoriate and cause problems but i winterize mine in mid november then get it out in march ,i use sea foam ,stabilizer and fog the engine and full tank of gas and never had any problems ,i change my lower unit lube and decarbon motor also ,the lower unit oil should always be changed beore cold weather incase of seal failure and water has entered the gear case before freezing weather.

[Herminator]

Airwave, I'm confused with your response. First you say "why wouldn't you start out in the spring with fresh stuff" (implying you store your tank empty) then at the end of your note, you say "fog and stabilize" implying that you store your tank full of fuel with stabilizer. So what is your final answer? Thanks a bunch.

[Airwave(OH)]

I stated in my first response to store your tank with very little. About 1/4 tank would be sufficient. That way it allows you to put in fresh (High Octane) fuel and bring the octane levels back up to where they should be because the stabilizer lowers your octane level . Sorry for the confusion. I wouldn't store it with an empty tank either. Although floats are no longer made of materials that will dry out, Gaskets are.