Petroleum Chemist hat on: Gasolines oxidize over time, that is it reacts with oxygen (air) and its composition changes. In fact the "oxidation stability" of avgas for instance is tested in the Refinery Lab. Also with long term storage the "light ends" or more volatile components including propane and butane etc will evaporate and in extreme cases you can end up with stuff resembling and smelling like varnish. My advice is take the fuel cap off and take a quick whiff. Oxidized petrol has an unmistakable putrid odour, once smelt never forgotten. If that's what you have, drain the stuff and you may have to clean the carby out also cos what's in there may well have turned to a sticky varnish like stuff. Having said that, if the fuel smells like normal fuel, give it a go, it should be fine. It all depends on what the fuel/ air ratio was in the tank and how hot the storage conditions were. Hat off!

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67 Deluxe
Dry suspension
1293cc, 11:1 comp, RE 282 camshaft, 45 Weber, extractors etc
4 synchro close ratio gbox
Cooper S brakes, no booster
Stealth box, as Doc says "goes harder and idles!"
RH tank cos I needed it crossing the Nullarbor etc..

Practical Person Hat ON: I have started engines with at least 20 year old fuel...does that make me a bad person?

This car has only been standing for a year...should not be a problem

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"Show me the Mini!"

Yeah Mick but back then petrol was real petrol, with tetraethyl lead in it.
These days it's more like 50% paint thinners or similar, to get the octane up. It's more solvent than petrol.
Until I painted my car with 2 pack recently, fuel cap leakage used to strip the acrylic paint off below the filler.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

OK Mick, an example.

A while I sorted out a mates Ducati 851. He tried to start it after it had been sitting for a year. Wouldn't start when I realized the fuel pump wasn't purring as it should. Had a look in the tank, less than a 1/4 full and fuel stank like off fuel does. Drained the tank and removed the fuel pump from inside (absolute PITA). The pump was completely seized with gunk. Soaked it in paint thinners for a day then freed it up by running paint thinners (great solvent) through it by changing the polarity of the wires. i.e running it forwards and backwards. Took quite a while to free it up completely. Reinstalled the pump (PITA!) and a few litres of fuel. The engine fired up but took a while and ran like an absolute dog. Wouldn't idle and wouldn't maintain revs at any throttle setting. Yep, injectors clogged with gunk. I made up a 5 litre brew of 50/50 petrol and paint thinners (methyl ethyl ketone or MEK, very high octane stuff so no problem). Started the thing up and ran the brew through it. After 10 minutes or so, it ran better and I was able to roughly maintain 2500 rpm. 5 minutes later the revs started climbing and ended up at 3000 rpm. I reduced back to 2500 and the thing happened. Eventually the injectors were fine and the engine was back to normal.
Moral of the story, if you're going to store a car/ bike for a lengthy period of time, drain the fuel and run the engine until it stops

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67 Deluxe
Dry suspension
1293cc, 11:1 comp, RE 282 camshaft, 45 Weber, extractors etc
4 synchro close ratio gbox
Cooper S brakes, no booster
Stealth box, as Doc says "goes harder and idles!"
RH tank cos I needed it crossing the Nullarbor etc..

I drain out anyway after a few months of sitting, which is quite normal for my car. What I syphon gets used in the mower..

Minis with SU carbs the fuel will evaporate out of the float bowl and the resulting varnish will glue the needle valve open (or sometimes closed). When the pump starts pumping it can overflow out the float bowl vent (or not fill at all).
I like to start them by filling the float bowl with fresh petrol after first cleaning the needle valve.

Its 'goodness' probably does deteriorates quicker but I think it does last longer, if that makes sense
I don't know why, but my son always fueled his Ford ute with Premium, anyway his car sat unused for 9 months
but it started first pop and ran ok.

Yep...modern fuels are for fools! However, we started out with a blanket statement which wasn't quite true...I have heard that 100 Octane might become available to the general public using older cars...that could be a good move (please, no comments, about my mate races a Cooper S and has a log book to get AVGAS etc...)

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"Show me the Mini!"

I think I might drain the tank next time I let it sit .

So I have no drain on the tank and am not going to remove it.
What methods do folk use to syphon please?
Tried tube-in-mouth once, never again

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'98 Mpi Sportspack + 7 port alloy head

I use a jiggle syphon. Available at all good car parts stores

A full tank is safer than an empty one

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"Show me the Mini!"

I call them 'car wankers'

If you have an electric fuel pump, you can just disconnect the carby and run the hose to a container, and switch it to ignition.

So I have no drain on the tank and am not going to remove it.
What methods do folk use to syphon please?
Tried tube-in-mouth once, never again [/quote]
I use a jiggle syphon. Available at all good car parts stores [/quote]

I call them 'car wankers'

If you have an electric fuel pump, you can just disconnect the carby and run the hose to a container, and switch it to ignition.[/quote]

I think I know what you mean by jiggle syphon; like a small plastic bellows?
Very aware that fumes from an empty tank are much more dangerous that a full tank.
Won't be trying to use the fuel pump in an injected situ.
Might come out a bit too quick!!

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'98 Mpi Sportspack + 7 port alloy head

This is a jiggle syphon: http://www.supercheapauto.com.au/online ... pid=312556

You post the valve-end into the fuel tank and the other end into a container, and jiggle the hose up and down. Hence, car w@nker.