Fuel Going Bad

Fishtales

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I've gotten (2) recent gas can fills at a local no-name gas station for my summer home lawn mower. I don't use that much each time, but noticed that the fuel only lasts about 2-3 weeks. The lawn mower runs very rough. I end up draining the tank, adding it all in my vehicle and going to the local station for another gallon. The first time I just thought bad gas. The second time has me thinking that the gas doesn't have the best or proper additives for gas life. Can gas go bad in 2-3 weeks? Has this happened to anyone else?
 

DennisG01

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The gas, nowadays, definitely doesn't last as long as it used to. But in 2-3 weeks? No. Especially not to the point that it's as obvious as you mentioned. But as you elluded to, who knows how long it was sitting in their tanks and what type of additives, if any, they added. Could it have had water in it? Did you happen to check for that?

Side note... I always add Startron to the gas cans for my mower, snowblower, weedwhacker, chainsaw, etc, etc. In 15 years, I've yet to have a fuel issue.
 

SirGrady226

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Once gas spoils, it leaves a residue in the container that contains natural organisms that break down petroleum. If the residue is not flushed out, it will cause the new fuel to break down and go bad much sooner.
 

g0tagrip

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I always buy non ethanol fuel for my power tools and generator. And my boat!
 

Lt.Mike

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Startron costs a lot and is good for boats and I’d use it for that but for yard equipment I use marvel mystery oil. You’ll notice a difference. In equipment that has a carburetor it will prevent its passages from clogging, the needle from sticking , varnish buildup, seals/gaskets from drying out, corrosion or rust and valves from sticking.
Honda motors (utility not outboards) in particular are prone to valves sticking. If a valve sticks open you have no compression and it just won’t start but if it sticks closed it will wipeout it’s nylon camshaft. A little shot of marvel mystery oil will prevent it.
In injevted engines it’ll keep all parts of the fuel system coated and clear, the injectors clean and have all the other benefits.
I use it in my mowers, farm tractors (antiques that still work hard for me, I have 6 :) ) snow blower, backpack blower and tiller.
Incidentally if you suspect you have bad gas in a mower DO NOT put that gas into your car or truck.
Yard equipment can run on crap that a car or truck can’t.
It’d be like shooting yourself in the foot. The repair bill that sour or contaminated fuel can cause will be high. Your looking at a couple of dollars in gas wasted at most, don’t risk it!
Honestly two week old gas doesn’t go bad that quick. I’d suspect one of the following with your mower.
The fuel pickup in the tank may be blocked. Vertical pickups are especially prone to that. The carb may be dirty. There is a small rubber diaphragm that serves as a fuel pump that wears out. Another simple thing that gets missed and can made an engine run rough is that that little pinhole in the fuel cap can get clogged with dust.
I’d suggest checking that and giving it a shot of the marvel mystery oil to the fuel first to see if that doesn’t help clear the dirt out and run smoother. If it’s a few years old I’d change out the fuel pump diaphragm, it’s only a couple of bucks.
 
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seasick

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The gas won't go bad that fast or anywhere near that fast. More likely is a problem with the mower. It may have gunk that gets dissolved by the fresh gas. Hopefully the mover is a 4 stroke. Did I understand your post correctly in that you suspected the gas went bad and then added it to your vehicle's tank?
 

Halfhitch

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Startron costs a lot and is good for boats and I’d use it for that but for yard equipment I use marvel mystery oil. You’ll notice a difference. In equipment that has a carburetor it will prevent its passages from clogging, the needle from sticking , varnish buildup, seals/gaskets from drying out, corrosion or rust and valves from sticking.
Honda motors (utility not outboards) in particular are prone to valves sticking. If a valve sticks open you have no compression and it just won’t start but if it sticks closed it will wipeout it’s nylon camshaft. A little shot of marvel mystery oil will prevent it.
In injevted engines it’ll keep all parts of the fuel system coated and clear, the injectors clean and have all the other benefits.
I use it in my mowers, farm tractors (antiques that still work hard for me, I have 6 :) ) snow blower, backpack blower and tiller.
Incidentally if you suspect you have bad gas in a mower DO NOT put that gas into your car or truck.
Yard equipment can run on crap that a car or truck can’t.
It’d be like shooting yourself in the foot. The repair bill that sour or contaminated fuel can cause will be high. Your looking at a couple of dollars in gas wasted at most, don’t risk it!
Honestly two week old gas doesn’t go bad that quick. I’d suspect one of the following with your mower.
The fuel pickup in the tank may be blocked. Vertical pickups are especially prone to that. The carb may be dirty. There is a small rubber diaphragm that serves as a fuel pump that wears out. Another simple thing that gets missed and can made an engine run rough is that that little pinhole in the fuel cap can get clogged with dust.
I’d suggest checking that and giving it a shot of the marvel mystery oil to the fuel first to see if that doesn’t help clear the dirt out and run smoother. If it’s a few years old I’d change out the fuel pump diaphragm, it’s only a couple of bucks.

Lieutenant, You and I think alike. I have been using Marvel Mystery Oil since the '60s. It's the best. I don't know why it isn't more widely marketed. It is good for so many things. It is good in a crankcase, in a fuel tank, great penetrating oil, a very good general purpose lube to put in your oil can to keep things from getting seized up, like bicycle chains, control cables, clevis pins and such. Another great thing about it is it smells so good......I think it would even be good on pancakes!...…..I'll report back......
 

Fishtales

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The gas won't go bad that fast or anywhere near that fast. More likely is a problem with the mower. It may have gunk that gets dissolved by the fresh gas. Hopefully the mover is a 4 stroke. Did I understand your post correctly in that you suspected the gas went bad and then added it to your vehicle's tank?

Yes, to get rid of it just burned the tank down and refilled. The mower is a 4 stroke. It happened 2X maybe there is residue in the can. Didn't think of that.
 

Lt.Mike

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Yes, to get rid of it just burned the tank down and refilled. The mower is a 4 stroke. It happened 2X maybe there is residue in the can. Didn't think of that.
To save $3 on a gallon of gas or just to get rid of gas you thought was bad putting it into your daily driver???
That’s just making headaches for yourself.
 

Fishtales

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Didn't have anywhere to get rid of it. It's long spent now.