How much time does it take for gas to go bad?

[Gradywhite3535]

How much time does it take for gas to go bad? Also when water gets into a fuel water seperator( not the one where you can drain it) does it just sit on the bottom of the filter? Can the water pass the fuel water seperator? Are you suppose to empty the filter and jut put it back or should it be replaced? Whats the easiest way of seeing if there is water in gas tank? I have a red portable tank. Thank you

 

[GA_Boater]

1 minute if you leave the cap off in the rain or over a year or more if the vent is closed on a portable tank.
Yes.
No.
Throw it away and replace with a new one.
Pump gas out using the primer bulb into a clear container and look for water on the bottom.

 

[QBhoy]

Many theories on this. Some say a year is too much, others say years are fine.
As GA says...all depends how it's stored. Also depends where it's sourced. Over here it's been proven that supermarket petrol is not only a lesser quality with less additives, but also is stored and transported in a less than adequate way, compared to premium brands.
All the above nonesense aside...it depends on how much you have...if it's only 10-20litres, from last year, is just top it up with a greater quantity of fresh fuel.
Either that or just ditch it.
Other theory is that one should either leave the fuel tank full or dead empty. Apparently avoids moisture build up.
I think this is more of a concern with diesel and not petrol.
For what it's worth, at the end of the season, I always run the tank as low as I can and have the last 20l mixed with 2 stroke at 50/1. Never had a problem in 30 odd years of ownership.
Might not answer your direct question, but hey, I'm on a role ! Haha.

 

[QBhoy]

Perhaps to answer more accurately to your questions.
If there is water in the separator, it will most likely sit there and be absorbed by the design of the filter. But only to a certain capacity. If there is any sign of water, change the filter and eliminate the source of the water. There should be no reason for water in a well kept petrol boat....especially from a remote tank like yours.
If there is any doubt...ditch it all. Water would only be visible in the tank if it was left to settle for a while and in disturbed. It will be at the bottom, having a heavier SG than the petrol.

 

[Old Ironmaker]

I was once told by my Chemical Engineer Bro-in law that works for Shell that some lower octane fuel with high Ethanol percentages has seen phase separation before it gets into you tank. Fuel quality is poorer when it has to be transported to remote locals such as the far North. They store less expensive fuels at or off site of the refineries as they play the commodity market game waiting for price increases. I didn't want to hear that. I can't help you with the fuel/water separator as I haven't had to deal with one. I have a 5 gallon tank for my 15HP kicker, depending how much I end up with at years end I may dump a gallon out and use it for a fire starter in the winter or my chainsaw etc. then leave MT and fill with fresh hi octane and 2 stroke mix the Spring . I always fill my main tank with hi octane when I winterize and have never had a problem in the spring. To me the key is to pay the Piper a few cents per liter and buy the best available fuel one can get. Shell V Power is my choice.

 

[Scott Danforth]

It takes as little as 2 weeks for ethanol fuel to phase separate. Cooler temperatures and being stationary is all it takea

 

[Old Ironmaker]

It takes as little as 2 weeks for ethanol fuel to phase separate. Cooler temperatures and being stationary is all it takea

Perhaps you can answer this Scott. I have been treating ethanol added fuel for the last 12 years since I bought this boat. 115HP 2 stoke Mariner. Where has all those little blobs of water encased by carbon go? That's what I picture in my mind when one talks of phase separation, I'm most likely off base there. I change my inline fuel filter once a year now and can see nothing in it. I forgot about it for the first 4 years as I was marine engine challenged at the time. When I did change it there was very little of anything I could see.

I hope this is still on subject and not a hi jacking. If deemed a hi jacking please delete.

 

[Lowlysubaruguy]

High ethanol and other foreign particulates ( the more people that handle your fuel before you get it the higher the unknown crap there is in your fuel) in fuels 3 to 5 months is enough to really turn these fuels bad. Most lawn mowers will barely run on fuel stored from october to March here in the NW. Two cycle may be a little more stable. Big factor is temperature swings as this brings in water which ethanol is magnet for making it even worse. Non ethanol fuels tend to be good for up to a year without

 

[Scott Danforth]

Perhaps you can answer this Scott. I have been treating ethanol added fuel for the last 12 years since I bought this boat. 115HP 2 stoke Mariner. Where has all those little blobs of water encased by carbon go? That's what I picture in my mind when one talks of phase separation, I'm most likely off base there. I change my inline fuel filter once a year now and can see nothing in it. I forgot about it for the first 4 years as I was marine engine challenged at the time. When I did change it there was very little of anything I could see.

I hope this is still on subject and not a hi jacking. If deemed a hi jacking please delete.

water and ethanol generally mix and go out the tail pipe as vapor

if you are running pre-mix, the oil has stability properties. no need to "treat" anything. just run it.

by inline filter, if you mean one of those see-thru filters, remove it. that is a fire hazard and is illegal in the fuel systems on boats.

 

[Old Ironmaker]

by inline filter, if you mean one of those see-thru filters, remove it. that is a fire hazard and is illegal in the fuel systems on boats.

The filter is not see through it is under the cowl on my Mariner, it is a Merc part I get from a dealer here. I slice them in half to see what's in there. May I ask why the safety issue with those see through filters? I have seen plenty of them on outboards. The Mariner has oil injection. I know many here call the phase separator treatments like 2+4 as bogus, the same as the tune up in a bottle stuff they sell. I run Shell Pro V which is supposed to be low Ethanol high octane and have been told I don't need any treatment. I am superstitious and for the cost I only put it in when I winterize. I remember correctly now phase separation gums up and degrades fuel lines.

 

[Trevor H]

Usually there is no problem leaving fuel in a tank during a six month season

Storing the fuel tank over the winter its best to empty the tank first

Its best policy to fill up with new fuel at the start of the new season

It depends on the quality of the fuel and the storage conditions