After much frustration I cant get the 3.9 Classic resto project to fire up. Good spark, good airflow plenty of fuel but no bang.

Had two 'knowledgeable' folks round to have a go without success. Then my mate who does autograss racing took one look / smell and said bad fuel chap- guarantee it!

I'm going to drain and replace the fuel this weekend but I wonder in my ignorance how long does unleaded last before its no good to get a V8 started? 405 AB exec seats Baltic and Cirrus
93 RR Classic efi

Remember it's easier to get forgiveness than permission!

Gone in order:
4.4 TDV8 SE - gone to a good home
93 Classic hard dash Plymouth Blue
03 L322 Oslo Blue
2000 Disco TD5 ES Epsom Green
98 P38 Rioja Red
89 Classic Cairngorm Brown

It takes a while to gel - but it could get contaminated almost immediately I guess......

Modern petrol in a sealed container will last for a considerable time - possibly years. The problem is when its put into a cars fuel tank which is vented to atmosphere. Then most highly volatile components in the petrol will tend to evaporate over time. As they do, the remaining fuel's volatility and ability to combust properly will degrade. The less volatile the fuel, the less effectively it burns in your engine. The result is diminished engine performance. Your engine may still start and run, but it probably will lumpy and keep cutting out until the engine has heated up. Ask any lawnmower owner who doesn't drain their fuel tank at the end of the season and then struggles to get it going the following spring.
Another problem with fuel is that over time condensation from normal thermal variations in the system will contaminate the fuel with water vapour. In both cases if you were using carbs this could cause real problems with starting or running but injector systems like your classic should produce a sufficient fine fuel mist to ignite although as I've said above rather poorly. The old petrol isn't total rubbish and can still be used by mixing with fresher fuel on a ratio of approx 4:1. Older petrol tends to be slightly darker than fresh and the smell is quite distinguishable so if in doubt you could try a visual check and sniff test! As a general rule of thumb I wouldn't keep petrol more than 3-4 months and when storing cars keep only a few gallons in the system and then fill with fresh when you want to use them.

I agree.

I had a Jeep GC with lpg fitted and only use petrol for starting.

I learnt to only buy petrol in lots of 5 litres at a time (once a month!) as once it went off (4 - 6 weeks) the car wouldn't start without fresh fuel being added.

Fuel will go bad over 3-6 months. But bad is a relative term.
Old fuel does not catch fire easily, fresh fuel does.
An engine is a differant issue tho, my rangie is currently running on 10 year old fuel ( from my old boat, i had been saving for my 24 buick but .....) that had lost almost half its volume in storage. It does not start easily but it does after a few seconds and runs fine once started.
Once its in the engine in the form of a mist a half decent spark will ignite it, if the timing is right.
I suggest its most likely you have a carb bowl full of crap/water or a bad spark.
Check your timing, i once had a rover 3.5 rr who lost a tooth on the dizzy drive so it started afterbtiming but over a few miles started running really badly and would not restart after a stop. I was very confused for a while, timing it every 30 mins before i finally realised it was not me making mistakes and thought it through.

Oh and should have said, get some easy start and spray in the intake, if it does not start with that its not a fuel issue. If it does start keep spraying for say 10 secs, once every thing in the carb gets wet it may run on the petrol.
Sounds silly but sometimes dry carbs do cause a lot of problems.
If it does start then look very carefully for vacuum leaks.
I also am assuming you have timed on the right cylinder and have the leads going to the right cylinders, easy to get these mixed up.

Thanks for the food for thought gents. TBH we have tried everything inc retarding advancing etc etc and bad fuel is really the last option.

If that fails its of to a specialist I'm afraid.  405 AB exec seats Baltic and Cirrus
93 RR Classic efi

Remember it's easier to get forgiveness than permission!

Gone in order:
4.4 TDV8 SE - gone to a good home
93 Classic hard dash Plymouth Blue
03 L322 Oslo Blue
2000 Disco TD5 ES Epsom Green
98 P38 Rioja Red
89 Classic Cairngorm Brown

Hi ,

Not sure if you know the history of your project - another thought would be to check compression on the cylinders I know it's unlikely that all 8 wound't have compression but if you have tried everything else you never know!!. Once had a friend that who's car stopped and didn't start - rocker shaft had broken in half!! .

Simon

Interesting, as I've had issues with fuel causing starting issues on my classic cars after about 3 months.
Once running fine, but just would not fire up or would just try to start.
Easy start & fresh fuel always cures the problem. Have a look around on the internet.

I have a classic and p38 in the garden neither have been on the road for nearly 4 yrs I move them about once every 6 months neither has had new fuel added and both start after a couple of turns - my guess is water in the carb good luck be interesting to see what the outcome is

Well new fuel made not a bit of difference although she seems to want to start better if that makes sense.

I'm going to get a man with a bigger brain to have a look at it now.

Either that or burn it!!!! 405 AB exec seats Baltic and Cirrus
93 RR Classic efi

Remember it's easier to get forgiveness than permission!

Gone in order:
4.4 TDV8 SE - gone to a good home
93 Classic hard dash Plymouth Blue
03 L322 Oslo Blue
2000 Disco TD5 ES Epsom Green
98 P38 Rioja Red
89 Classic Cairngorm Brown

Have you checked the compression?

Know it sounds daft but the leads are on the right plugs had a similar issue when replacing coil packs on p38 got in a right muddle and plugged it all up areas about tit
just a thought
Or indeed is the spark strong enough ?

ajac8 wrote:

After much frustration I cant get the 3.9 Classic resto project to fire up. Good spark, good airflow plenty of fuel but no bang.

Had two 'knowledgeable' folks round to have a go without success. Then my mate who does autograss racing took one look / smell and said bad fuel chap- guarantee it!

I'm going to drain and replace the fuel this weekend but I wonder in my ignorance how long does unleaded last before its no good to get a V8 started?

I would take all the spark plugs out and let it stand overnight, it may be flooded, or take the FI fuse out and crank.

If you can put the ignition timing back to where it was

I have cars that have stood for years, but start no problem. I have has V8's for years, if you need a sounding board drop me a line  Regards
Royston

2008 4.2 Supercharged Autobiography
1994 Classic Vogue SE
1999 Rover BRM
1987 Rover Vitesse Twin Plenum