*old* fuel

[Nade]

My bikes been sitting unused for the last 6 weeks due to a knee injury.......today I got the brace of my leg and decided it was time to bring the bike out and give it a run. Wouldn't start....battery was nearly dead...but still turning over...usually it bursts into life pretty good. Eventually it fired...but ran really rough...3 then 4 then back to 3 cylinders. Eventually it came right but smelled like fuel thats been left out too long and gone off. Some one tried to tell me that fuel dosent go off anymore due to the 'new mixes' but it smelled really bad...not oily or anything..just like a petrol container that hasn't had fuel in it in ages. Anyway I got it warmed up and took it for a ride..(knee protested really bad and came home after about 1km up the road)..it missed and farted and only came right after grabbing a handful and taking it to the redline.....but then went back to missing and farting....is it just the fuel...should I clean the carbs. Im changing the fuel anyways but was just interested in people opinions.

[MSTRS:Me]

My bikes been sitting unused for the last 6 weeks ....is it just the fuel...should I clean the carbs. Im changing the fuel anyways but was just interested in people opinions.

More likely that the fuel in the bowls evaporated (explains the hard to start thing) and has left a glaze in/on the jets. 'Spirited' use should sort that.

[imdying]

Has it been sitting outside where water may have either gotten into the sparkplug recesses in the head, or seeped into the gas tank via the fuel tank cap? Water in your fuel will do that, as will a shorting or rusted end (boot end) plug.

[Steam]

Six week old fuel is nothing in terms of proper running. For max performance it'd matter, but just for pootling around no. There must be something else wrong.

[ajturbo]

we started AND RUN a MB100 that had fuel that was ATLEAST 15months old....

[98tls]

Have left a car in the garage for 2 years put a battery in it and it fired up straightaway,fwiw.

[JimO]

i have a V8 falcon that ran on 5 year old gas (i did pour some fresh stuf down its neck to get it going)

[T.W.R]

If the bike has been sitting outside for a few weeks it could easily be a case of moisture that has got into places it shouldn't have, or a MSTRS said the fuel in the float bowls has evaporated, most possible and if the carbs haven't been apart for a long time any sediment that has been sitting in the bottom of the bowls could have easily been sucked into the jets of the carbs that are fluffing around.

The fuel wont have gone stale after that amount of time, a good example is a bike I've been sorting out at work; a 87 GSX750SF Katana that had been sitting in a shed for 3yrs.
Ripped the battery out as it had calcified 3 cells, hooked up a fresh battery, drained the float bowls (the remnants of fuel that came out was GREEN) primed the carbs with the fuel that was still in the tank (smelt off), switched her on, opened up the choke & hit the starter button, the engine spun over a few times then caught on 2 pots then 3 & finally all 4 and sat at a steady 3500rpm slowly eased off the choke and it sat idling (slightly rough but still idling).

[FROSTY:Me]

What he ^^^^^^ said. With My Gs500 itd been sitting for yonks and it started and ran just with a jumper battery

[jim.cox]

The fuel wont have gone stale after that amount of time.

I beg to disagree.

I think there is a very good chance that stale fuel may be part of the problem here

The 96 octane fuel only lasts about 8 weeks from production at the refinery before it goes off.

And you dont know how long it took to transport or how long it has been sitting at the petrol station.

[scumdog]

CBs Sporty sat for a year with the odd start-up to keep things running, a year after being praked-up it still started and did the Southern Coastal trip ok with the same fuel (well, until topping up at Mataura).

So fuel will last better than it did shortly after unleaded was sneaked onto us.

[YellowDog]

I beg to disagree.

I think there is a very good chance that stale fuel may be part of the problem here

The 96 octane fuel only lasts about 8 weeks from production at the refinery before it goes off.

And you dont know how long it took to transport or how long it has been sitting at the petrol station.

I agree with Jim.

Under some conditions the fuel goes stale and separates. You can get an additive to flush through the system, which will hopefully will remove any debris.

Do check all of the obvious stuff first.

Good luck.

[scumdog]

I beg to disagree.

I think there is a very good chance that stale fuel may be part of the problem here

The 96 octane fuel only lasts about 8 weeks from production at the refinery before it goes off.

And you dont know how long it took to transport or how long it has been sitting at the petrol station.

I've had cars/bikes sit waay longer than 8 weeks and still be able to be started and run on such old fuel.

Think what you want but my experiences show that if the ignition is up to it you won't have worries after six months let alone six weeks.

[jim.cox]

Under some conditions the fuel goes stale and separates. .

Its not so much separation as evaporation. Some of the additives in 96 are particularly volatile - ie Toluene - and evaporate more quickly. So it goes from 96 to more like 91. Some motors wont notice this, others will.

If the fuel in the carb bowl has gone stale its going to take quite a lot of cranking before any good fuel gets through to the cylinders. Injection systems seem less prone.

I have two engines that are unhappy on old fuel and one that doesnt seem to care.

As our american cousins say, "Your mileage may vary"

[Nade]

well.....problem solved. I changed the fuel.....started it up....bit rough. warmed it up and then held the throttle open some and let it rev between 8000 and 10 000rpms for a bit.....then it idled fine...smelled much better. Just have to wait till my knee heals some more before I take it for a 'spirited' ride.

cheers for the info guys. I too can remeber starting my old RX7 years ago after it sitting for around 6 months and it smelled much the same...ran ok...but ran heaps better once I had filled up with new fuel.
I have spoken to a fuel tanker driver who said that the fuel now days is a hodge podge mix. He himself has mixed fuels in tanks and seen ships unloading pumping fuel into tanks used for another type of fuel.....admittidly the quantiys mixed are a infanticimal percentage due to the huge amounts held by those tanks....but still...makes ya wonder.