Gas evaporation question

[The Grail]

I have a portable 6 gallon tank of gas on my boat as a holdover from when I first got it a month ago. It was a backup in case I had any problems with the gas that came in the built-in 40 gallon tank. I still want to keep it on board for a backup until I feel completely comfortable with the built in system. (The bulb went flat twice, but I think I've resolved it.)

The spare tank stays on the boat, and I have the vent open, so it doesn't puff up in the hot sun. Do I need to worry that evaporation will render the gas unusable any time soon?

Also, besides the safety considerations, is it a good idea to have a spare gas tank on board a 25 year old boat with a 33 year old motor, just in case, or am I just worrying too much?

 

[shade788]

Re: Gas evaporation question

I can understand your situation. I keep extra gas on me at all times just in case.

Here is what I do or would do in your case. Keep the tank in a well ventilated area with the vent open on the tank. Evaporation from my experience isn't a problem.

I would put the recommend dosage of STABIL in the 6 gallon tank just to be safe. Also during the season I would rotate the gas every few fills. What I mean is pour the 6 gallon into your main tank and refill it with fresh gas. That will give you reliable gas and you won't have to worry about it going bad on you.

Just my 2 cents...

 

[tashasdaddy]

Re: Gas evaporation question

agree with shade, also with a 25 year old tank i think i would want an inspection. what material, is it made of. when is it going to spring a leak. safety first. what kind of gunk does it have in it?

 

[jeeperman]

Re: Gas evaporation question

I would change it out with fresh fuel before adding Stabil.
Use Stabil in the main tank and have zero in the jug during long term storage.
The next question would be how much emergancy gas do you really need to keep onboard?
Do u really need 6 gallons when 1 gallon would get you back on an average outing?
Also consider what to do when you need to use that emergency gas.
You will want that e-gas when you run out by mistake or because you have sucked crap out of the main tank.
If it is the later, you probaly won't figure that out until after you have dumped the e-gas into the main tank and the engine still won't run.
But if you plan ahead you can disconnect the feed line from main tank to suck out of the e-gas jug instead to avoid that.
Also if your running straight gas to your oil injected 2-stroke, your e-gas should have 2-stroke oil in it.
That way if your oil tank goes dry or your oil injection system quits, you can feed the engine with the e-gas jug.
So what if it smokes some if u need it for the gas but not the oil.