stale fuel ? how long till petrol is gone off?

[Bill Edwards]

It can certainly go very off in a few months, just yesterday I got a strimmer running by replacing the fuel. Very common problem to the point where if something doesn't get enough use it's daft not to put something in to prevent fuel deterioration.

 

[MoreWellie]

Got a car with half a tank full that has been standing 3 or 4 years and only started 2 or 3 times in that period and each time it starts on the turn of the key and runs fine

just ordinary sainsbury fuel

2 stroke mix doesn't like being kept though so strimmers and chain saws I am not surprised

 

[Lufbramatt]

did it look /smell like fresh stuff ?

Yep looked and smelt fine.

 

[pedrobedro]

I once bought a bike that had been stood in a garage for ten years. The fuel was like napthalene (mothballs). That was an exceptional case and it got recycled into cleaning duties. Didn't half stink mind!

On the other hand I picked up a (crashed)bike the other day that had been stuck in a garden for two years. Fuel smells good, probably stick it in the van or strimmer/chainsaw.

Not familiar with modern fuel mixes separating but I will look out for it.

Otherwise: use your nose.

I fixed an old Diversion a while back and it had been stood a couple of years. I had to buy some carbs as the jets in the originals were shot, the brass had gone black and the holes were rotted out. The float bowls were full of what looked and smelt like green gloss paint.

Just finished using up the 60 litres of 8 month old petrol I took out of my BMW, my old Passat ran fine on it but I stuck it in 20 litres at a time so it was mixed in with fresh fuel.

Is the Passat a diesel though ? (joking)

I use Aspen alkylate fuel in my chainsaw, it's nearly £20 for 5 litres but it will keep for 5 years in the can or in the saw.

 

[Screwdriver]

I bought an old VW Passat estate a few years ago. It was super cheap but had an awesome number plate K1 P**. Seller told me to bring some petrol because the tank was almost empty. I dumped 5 litres in it and the needle stuck resolutely at zero.

"See? It moved." He says, err well ok....

Got it home and a few minutes on Google told me the instrument panel is notorious for developing dry joints. Pulled it out, soldered it up and everything fired up ok. In fact more than ok. The fuel meter just kept going up, and up, and up until it topped out! The old car was brim full of fuel - worth about as much as I had paid for the car!

Oh. It ran fine by the way. On old (free) fuel...

S.

 

[steveo3002]

mixed reviews then....some say its rank after a few months others say it still works after ages

i guess i have to buy fuel anyway so its not a bad start , saves replacing good bits if theyre fine , damn spark plugs are £60 a set

 

[Bill Edwards]

Just give it a sniff, that seems a pretty reliable way to find out if it's gone off or not. It should have the nice, strong and clear smell of petrol, once it's gone off it's quite different.
I have had not very much keep a lot of months or more in a can just fine but it can also be gone in no time at all. There's no set time which you can say it's no good after.

 

[Crater Creator]

Seems like it's the flashing off of the lighter components which would cause a problem. Aided by thermal cycles in something like a car's petrol tank, which will keep "breathing" and taking the light vapours away and replacing them with fresh air, helping the evaporation..
If you can store it in a container which stays sealed at above the natural vapour pressure of the liquid (up to about 10psi), it should keep indefinitely.
Newer ethanol fuels will absorb water, and carbs will give more trouble than fuel injection when using degraded fuel.
I keep all mine in jerry cans with good tight rubber seals, and the mower starts every year no bother after sitting for a whole scottish winter.
For 2-stroke, I always run the chainsaw and strimmer dry after use, until they stall. Seems to help stop them gumming up with oil, then when I refill from the jerry can they fire up no problem. My (almost empty) 20 liter can of 2-stroke mix is about 5 years old.

 

[bricol]

My old ,91 Pug 106 1100 wil start fine on years old fuel, and even run reasonably well - until you want to work it - up a hill for example. Then it misses every so ofte. Fuel injected Caterham with a K-series engine simply sputters and generally runs crap. Whereas the 1600 X-flow on an SU carb in my Dutton trials car just starts, runs, and pulls fine on the trials hills. It'd been sat for 3 years or so - charged the battery, run the electric pump to get fuel up to the carb, pulled the choke, started it - first turn as always -, choke in, on the trailer, pump off, to the trial . . . won the class ;-)

Depends on the fuel and the additives in it, and the state of tune of the engine I guess as for it's tolerance for low octane fuel.

 

[Cobs]

My lawnmower sits over winter and always fires up first time in the spring - only time I've ever had a problem was when i decided to add a fuel stabiliser one winter - gummed up the carbs and had to rebuild them....

 

[Country Joe]

I use Aspen alkylate fuel in my chainsaw, it's nearly £20 for 5 litres but it will keep for 5 years in the can or in the saw.

Same here, brilliant stuff, starts quite easily after a good long time.

And that's even with a ruptured right bicep that flops about, down near my elbow!
It's been a godsend since I f***ed up that shoulder.

All the Best,
CJ

 

[Country Joe]

Also, despite being quite pricey, it seems to start more easily than fresh pump fuel, even after a few years.
Not sure how much heat affects fuel storage, but sometimes everything gets slow-roasted in a shipping container, which probably doesn't help.

CJ

 

[steveo3002]

update
went back to the car untouched sinse i last posted , misfire has 90% cleared up now , wonder if it was a injector starting to gum up?

stuck some more petty in and a can of inj cleaner and see what happens next lol

 

[Nick67GT]

Here's a couple of ideas from the current edition of Practical Classics which help to deal with the problem of stale fuel & ethanol:





Ethanol removal seems a bit of a fag though.......

 

[Rocketman]

update
went back to the car untouched sinse i last posted , misfire has 90% cleared up now , wonder if it was a injector starting to gum up?

stuck some more petty in and a can of inj cleaner and see what happens next lol

Yeah that's really the biggest problem leaving a car. You may need to get them ultrasonic cleaned if it doesn't sort it. The injector cleaner won't fix it if it's really bad.