# Drain gas tank or just add new gas?



## the hammer (Mar 15, 2019)

I've had some fuel since 2016 with additional added in late 2017, about 1/4 tank/1/3 left. Should I drain the tank a bit or just add some gallons to what I got and some fuel stabilizer or some such. Thanks.


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## DaleH (Mar 15, 2019)

If not E10 or Ethanol fuel, I had great luck adding PRI-G gas treatment to 50-gals of years old fuel that was then burned through an old carb’d V6 OB, but I ran an external Racor 10-micron drainable fuel/water separator on it. Replaced the f/w filter afterwards.

Not sure I’d take the chance on old, suspect fuel if ethanol based ...


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## Superlucky (Mar 15, 2019)

Drain it!
Today's fuels start to go bad within weeks. 
I dump all of my questionable fuels into a can and run them through my lawnmower.
Why take the chance?
Bill


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## nccatfisher (Mar 15, 2019)

Dump it.


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## KMixson (Mar 15, 2019)

Drain it. It would be much easier to drain it than to have to go into your carbs because of bad/old gas.


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## the hammer (Mar 15, 2019)

Was able to find the fuel capacity is 16, so it's got between 3 and 5 gallons.


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## Crazyboat (Mar 15, 2019)

the hammer said:


> Was able to find the fuel capacity is 16, so it's got between 3 and 5 gallons.


Suck it out into a 5 gal container and add it one gal at a time to your car, you'll be fine.


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## Pappy (Mar 15, 2019)

We deal with this on an almost weekly basis. Customers always proudly tell us they just put fresh fuel in.....
Much cheaper to drain and get known good fuel in the tank, lines and complete powerhead fuel system.


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## the hammer (Mar 16, 2019)

Pappy said:


> We deal with this on an almost weekly basis. Customers always proudly tell us they just put fresh fuel in.....
> Much cheaper to drain and get known good fuel in the tank, lines and complete powerhead fuel system.



So, hook up the boat and drive around the block to shake up any sediment in the tank?


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## overboard (Mar 16, 2019)

I would drain it also, especially if it's ethanol. I do the same as others mentioned, drain the tanks and add it little by little to fresh gas in the garden tractor or zero turn along with some sea foam, no problems yet.


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## CedarRiverScooter (Mar 16, 2019)

If the carb gums up partially, it can cause a lean condition & burn up a piston. Common on jet skis, maybe not applicable to an outboard.


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## Pappy (Mar 16, 2019)

the hammer said:


> Pappy said:
> 
> 
> > We deal with this on an almost weekly basis. Customers always proudly tell us they just put fresh fuel in.....
> ...



???
If you have sediment in the tank you have bigger issues than just stale fuel.


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## the hammer (Mar 18, 2019)

Pappy said:


> the hammer said:
> 
> 
> > Pappy said:
> ...



There was no actual sediment in the tank diagnosis. I was just tossing out what was in the tank was mixed. I don't know how to say what I'm trying to explain. The boat's been sitting in the garage for a few months.


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## el_cheapo (Mar 18, 2019)

the hammer said:


> I've had some fuel since 2016 with additional added in late 2017, about 1/4 tank/1/3 left. Should I drain the tank a bit or just add some gallons to what I got and some fuel stabilizer or some such. Thanks.



Dump the fuel and start fresh, I did some garage renovations this winter and ended up with some rain water in my fuel tank (didn't realize) boat ran fine for about a hundred yards then the sloshing mixed the fuel and water and I couldn't even sputter. Paddled back upwind and dumped the carb bowl/tank of gas. Refilled and life is good but I'm never risking an iffy tank again.


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## Pappy (Mar 18, 2019)

Okay, then what I will tell you is this. 
Gasoline is cheap. Powerhead damage, high pressure fuel pumps, lift pumps, vapor separators, pre-formed fuel lines, carb rebuilds, etc. are not. 
I have seen and made out bills in the thousands for folks that tried to run large carbureted and injected engines on junk fuel. Smaller engines are not so bad at least but for the price of a few gallons of gasoline??
Get rid of "questionable" fuel in your tank, boat fuel lines and all fuel lines under the engine cowling, replace with fresh and never look back! How'zat?


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## turbotodd (Mar 18, 2019)

You cant make bad gas good again by dumping good gas on top of the old. It don't work that way. Dump it, start fresh. Or do you like being stuck in the middle of the lake/river trying to flag down a tow?


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## KMixson (Mar 19, 2019)

If you are in doubt about the quality of fuel in your tank, drain it. It is not worth the risk to try and save it and do more damage to the motor and your wallet trying to save a couple of bucks. I would not be willing putting it into a car or truck either. Cars have catalytic converters on them that the oil mix will not work well with. If you want to save a couple of bucks and spend thousands on a new catalytic converter, go ahead and pour it into your car. If you are bound and determined to use the fuel I would suggest pouring it into a small older lawn mower that you can access the cab real easy so you can rebuild it without too much hassle. The mower may not even run on the fuel depending on the oil mixture in it. Be warned, some of these newer carbs on the small mowers are not able to be rebuilt. They are made of plastic and are molded together so you have no way to take them apart to get to the insides to clean them.


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## the hammer (Mar 19, 2019)

Pappy said:


> Okay, then what I will tell you is this.
> Gasoline is cheap. Powerhead damage, high pressure fuel pumps, lift pumps, vapor separators, pre-formed fuel lines, carb rebuilds, etc. are not.
> I have seen and made out bills in the thousands for folks that tried to run large carbureted and injected engines on junk fuel. Smaller engines are not so bad at least but for the price of a few gallons of gasoline??
> Get rid of "questionable" fuel in your tank, boat fuel lines and all fuel lines under the engine cowling, replace with fresh and never look back! How'zat?



I was going to drain and change after the first couple of replies. After that, I was just curious as to why adding 10 gallons of fresh to 4 "stale" would make a difference.


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