old petrol

[phil63]

My one Minor has been standing for 3 months , when I tried to start it , it wouldn't have it till I filled the float chanber with some new petrol . then it fired straight away . Yet my lawn mower which hasn't run since October started with no problem . Has anyone else had this problem ? how long will petrol last ?, have I got to drain out the 2 gallons that are in the tank ?
Philip Burley

[simmitc]

Petrol certainly does go "off" but I'd have thought that 3 months should have been OK. Is it getting fuel through to the carb? Perhaps the pump is gunged up as the old fuel evapourated in storage?

[bigginger]

And even if it has gone off, with only that quantity in there you should be fine just putting in more on top of it.

[rayofleamington]

I've only had it from petrol >6 years old.
The only possibility that it happens after 3 months is that the petrol wasn't good to start with or that it was not completely related to the age of the petrol (eg carb not filling) and the fresh petrol helped get it starting (sometimes the engine vibrations can help cure other problems)

[bmcecosse]

Are you sure the fuel pump was pumpimg any fuel up there ? My car has been sitting all winter - and still starts up no problem with the old fuel.

[Arfron]

The advice given with my lawnmower is that 30 days is about the maximum you should keep unleaded petrol , I have also read the 30 day statement in various motoring sources. Add new petrol on top of the old usually gets it going Arfron

[bigginger]

Is the lawn mower 2 stroke? That's the only thing I've ever seen that sort of time limit for - the oil separates from the petrol.

[Arfron]

The mower is 4 stroke -Wollf. It states the 30 day thing in the 'destructions' booklet !! I think that 'Honest John' in the Telegraph has mentioned the 30 day limit , approx , on un-leadad petrol Arfron

[bigginger]

Blimey - You learn something new every day - though I must say I tend to take a lot of 'honest' John's advice with half a sack of Saxo...
a

[Arfron]

That's true -- but I guess Wolf info. is probably accurate . In fact couldn't start the machine -- Wolf rep. told me to put in new unleaded petrol -- problem solved . There you go !!!! Arfron

[Chris Morley]

I think it varies a lot - it seems unlikely that it will ever go off on the 31st day though. The fuel in my traveller is a mixture of petrol between 5 months and 20 months old but it started easily on a cold January day (after pre-warming the engine bay).