Tank full or empty?
 

OK :eek: I am getting more and more confused. First for all is there ethanol in the gas that's being sold on and around the lake? If so my question is what is the best way to store your boat with the tank near full with stabilizer not to allow condinsation into the tank or near empty with stabilizer not to allow the ethanol to do any damage to the tank??:cool: Any advise?:look:

Happy reading...

http://www.winnipesaukee.com/forums/...ead.php?t=3722

I would store the boat with the tank full with stabilizer. From what I read of the links supplied in the other thread, the ethanol becomes a problem if there is water in the tank. A full tank will not allow enough water to condense to be a problem. I am paraphrasing what I read but that is the general idea.

The other issue brought up in that thread is fiberglass tanks. I don't own any fiberglass tanks so it really doesn't concern me. If your boat has a fiberglass tank then you should do more research.

Finally, when I asked this summer, a marina operator told me that the ethanol gas wasn't being used on the lake so it may be a non-issue.

By Law it has to be posted on the pumps if it is blended with Ethanol and I haven't seen any postings on any Marina pumps I have been to. For that matter, Sam's Club in Concord is the only one I have seen at all that has Ethanol blended gas. I plan on the usual...fill the tank, stabilize it and take a short run to get the stabilized gas through the system.

From Mercury's website
 

Here is a link on Mercury's website re: ethanol.

http://www.mercurymarine.com/ethanol2#1379

Nice FAQ's.

I asked at my local marine parts store how to winterize a boat using 10% ethanol. They said to leave the tank either bone dry (not practicle) or fill it up to the top. They also said to use a stabilizer that does not contain alcohol.

If the gasoline you use has ethanol it has to say so at the pump.

I don't know anything about whether or not to use an alcohol free stabilizer if your gas contains ethanol. What I do know is that you should not completely top off your tank. Expansion will occur and you will have fuel leaking from the tanks expansion valve. I learned first hand about this early last spring when the boat above mine in our rack storage leaked on my boat and several boats below. I lucked out, but others suffered gel coat damage. My mechanic said to fill the tank between seventy five percent and full, and add an appropriate amount of stabilizer. It's a good idea to run the engine after doing this so the entire fuel system is exposed to the stabilizer. It's best to do this while underway so as to mix the stabilizer with the fuel (doesn't get much agitation at the dock:) )

Here's an explanation...
 

...From Mercury, as found in the link in my earlier post (#5, I think).

Here is an excerpt from that link, courtesy of Mercury:

(Q) What should be done when storing boats with ethanol-blended fuels for extended periods?


(A) When preparing to store a boat for extended periods of two months or more, it is best to completely remove all fuel from the tank. If it is difficult or not possible to remove the fuel, maintaining a full tank of fuel with a fuel stabilizer added to provide fuel stability and corrosion protection is recommended. A partially full tank is not recommended because the void space above the fuel allows air movement that can bring in water through condensation as the temperature cycles up and down. This condensation potentially becomes a problem. Mercury Marine Fuel System Treatment & Stabilizer can help maintain fuel systems in storage. It contains oxidation inhibitors to reduce oxidation and gum formation, metal chelating agents to protect metal components from corrosion, water absorbing agents to reduce the presence of free water, and dispersants to help suspend and disperse debris. It is best used by adding to the tank at the recommended dosage, running the engine for 10 minutes to allow the system to be cleaned, shutting off the fuel valve to interrupt the fuel supply and allow the engine to run until it stops, topping off the tank until it's full, and capping any openings to reduce the amount of exchange with the air that might bring in condensation.

Rinkerfam, I understand your concern about overflow, but I think with ethanol 10 in your tank, better to be virtually full, than 70%. Just another opinion from that of your mechanic.

Before ethanol, there were two schools of thought. Leave your tank nearly full or nearly empty.

The full school was based on the condensation theory. If the tank had room in it, as the temperature went up and down, air would be sucked in and out of the vent. The air would have moisture that would condense on the walls of the tank and add water to the fuel. The downside of this plan is you have a full tank of old gas in the spring.

The empty school is based on the dilution theory. Even if the gas gets a little water during the winter, adding a bunch of clean new gas in the spring will dilute it.

The only difference in an ethanol world, is that water can cause more problems. I don't think anyone has enough real world experience with ethanol to really know how bad things are yet.

Personally I think the whole water condensation thing is a bit overblown, especally with our dry winter air.

When adding stabilizer to fuel tanks,I always add it BEFORE fueling so movement of the fuel being introduced will mix the stabilzer thoroughly.Then run your engine for 5- 10.

Keep it fuel and use a stabilizer
 

Gas and water DO NOT MIX! Condensation will form from empty fuel tanks.
I've had problem every Fall when it starts getting cold at nights, if I don't keep the tank full. The water settles to the bottom of the tank and that's where the fuel lines pick up. Water and the E10 gas aren't good together at all.

I'd guess I'm at about 80% full for the next 7-months....hopefully, it is a good level! I'll let you know in mid-April 2007 when I try to turn the old girl over.................

Use isopropyl based dry gas this time of year. It absorbs all the water and the mixture mixes with gasoline. I use it in my steel fuel tank equipped motorcycles to prevent rust.

unfortunate real world experience
 

Last fall I left the tank half full with the proper amount of Sta-Bil (fuel stabilizer). This summer it cost $1600 to get the ethanol issue to where I THINK it is resolved.

The gel that formed looked like pudding and clogged the fuel filter and ruined one of the fuel pumps (2001 496 Merc MPI). We eventually decided to install a Racor 10 micron filter which is twice as restrictive as the OEM unit from Merc.

After implementing the Racor system, we decided to just run the bad fuel/ethanol mix through the system. This decision was based on the reluctance of the marina to try to drain the 92 gallon tank and the expense of disposing of all that fuel. Also, there is no way to completely drain a baffled fuel tank without removing it.

I then emptied the Racor filter after about each hour of use. This produced some pretty nasty stuff, but it was effective. After about three or four tanks of fuel, it now SEEMS O.K. And, in spite of the Merc bulletin listed above, there have been no fuel restriction issues with the Racor 10 micron filter. The engine attains full RPM.

This winter? Full tank, no doubt about it.

Peter

Oh yeah, almost all of my boating was on Cape Cod.

fuel lines
 

I think for the last 20 years I have been fortunate. When I finish my boating season I put a can of dry-gas in what is left in the tanks, sometimes half empty, sometimes half full I put the boat in the water next season turn the key. Never any problems, oh and I close the vent on the tanks. Only problem I ever had was with the fuel line, (outboard) the bulb rots.