Do you really need to fill gas tank for winter storage

[seadoo_mike]

I store my boat inside an unheated garage for the winter here in PA. Could it be possible to store with the gas tank empty, my thought process is that if the fuel tank is vented and I leave the gas cap off that the temperature and pressure will be the same in the tank and outside of tank, so there should not be any moisture to collect inside tank, and also the fuel tank is fiberglass so there shouldn't be any temperature change on inside. Not sure but would I be correct in saying

 

[LouDoo]

You know that's really a good question. "They" use to say when boats has steel gas tanks to drain the gas, when we went to molded plastic tank "they" said top them off. So who really knows, (maybe "they" do), I can tell you what I do, I just store my ski's and boats with whatever fuel is left in the tank. The ski's usually have about 1/4 to 1/3 of a tank, and I just treat whatever gas is left with fuel stabilizer. In the spring I top the tanks off and add the appropriate amount of fuel stabilizer.

I do keep my ski's stored inside in an unheated garage in the basement, and it rarely if ever gets below freezing in the garage.

Lou

 

[chucked]

I think they say to do it because there's less surface area inside the tank for condensation to build up on.

 

[racerxxx]

It does have to do with condensation, I used to top it of, now I just leave it where it is on the last ride. I also put marine sta-bil in the gas, no problems. Hot or cold those engine bays sweat, do you top it off after every ride?

Sent from my SGH-T889 using Tapatalk 2

 

[Luv2Camp]

Two scenarios.... Non ethanol gas should be topped off to full tank to eliminate room for condensation. Ethanol blended fuels ideally should be stored empty or as close to empty as possible as the ethanol actually binds water molecules to it and can cause phase separation which can cause issues...

Having said that, I do store full tank and go overboard with adding Marine Stabil and Stabil Storage into the tank which is supposed to help stop the water binding and phase separation. I also store indoors and not in humid conditions so less of an issue.

 

[seadoo_mike]

racerxxx, I use to live in Chalfont behind Target World, now I'm up in Gilbertsville, I don't top off after every ride. So with your guy's replies the reason for filling all the way is to keep the moisture from attacking the gasoline and not the tank surface, my feeling was that you kept it full to keep condensation from forming on the inside walls of the tank, I do use marine ethanol stabil (green stuff) for storage and during the season. I did always fill the tank full for storage and treat it with stabil, but I was thinking is it really necessary

 

[seadoo_mike]

thanks for the info. guy's, I am probably going to leave in whatever is left and of course stabil, or I may try to get out the last of the old gas and leave empty.

 

[chucked]

If you want to drain it, it will need to be DRY. Any small drops will turn to varnish.