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Thread: Carburetor problem

  1. #1
    Guest falcon's Avatar
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    Carburetor problem

    Hi I’m running a Cleaveland 2v with 4 double Webber carbs 40dcoe series 35. This started a year ago at wheels day. Now the engine won’t start. Iv renewed the point/ leads/ plugs/ disi cap/ rotor arm/ coil. Had it running to check with a timing light. Sparking on all plugs plus disi cap. Points set at 20 th . It used to run but it’s got worse and I’m thinking it’s possible too much air coming in to the carbs. Thinking the fuels not turning into vapour. Iv looked in the Haynes book but can’t find anything that’s helpful. As I said it started a yedd as r ago and has gradually go worse so the small air problem is know a big air problem. Any ideas you all. Cheers for reading this.

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    Have you tried to start it with a good dose of fuel from a squirty bottle?

    Chris
    Last edited by Happydaze; 21-06-20 at 11:41 PM. Reason: silly typo, does not dose!!!
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    There’s fuel. It’s just fuel that’s the problem it needs to be vapour. As I believe fuel doesn’t ignite vapour does

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    NSRA member Morris460's Avatar
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    It's atomised fuel that burns not vapour.
    What Happydaze said.
    Layabout.

  5. #5
    NSRA member kapri's Avatar
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    Quote Originally Posted by falcon View Post
    There’s fuel. It’s just fuel that’s the problem it needs to be vapour. As I believe fuel doesn’t ignite vapour does

    There's liquid there , you are presumimg it's petrol When the light ends evapourate from fuel normally 6-12 weeks it won't start without fresh fuel added.
    Last edited by kapri; 21-06-20 at 10:29 PM.
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    That’s what I meant ����

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    Kapri can you elaborate on that please bud

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    The storage life of petrol is one year when stored under shelter in a sealed container. Once a seal is broken the fuel has a storage life of six months at 20°C or three months at 30°C. The storage life of petrol in equipment fuel tanks is one month.

    Petrol will generally last for around 3 weeks at summer temperature in a vented fuel tank, after which time the performance will suffer, and it will be best to add fresh fuel to restore the performance. Petrol in a sealed container will last for more than 6 months before the performance suffers too much.
    you will have seen additives for the likes of Lawnmowers and some manufacturers do recomend the use of the additive

    Stan

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    NSRA member mygasser's Avatar
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    don't believe the liquid fuel won't fire thing. it's quite normal to slosh an egg cup or 2 (approx measure out of whatever's to hand) of 'liquid' fresh petrol down the carb throat to fire an engine with empty fuel bowls. it'll usually run enough to pump fuel to the carb. try some fresh bought petrol down the carbs to see what happens, with your webers maybe put fuel in an old washing up liquid bottle, hold the throttle full open and go along the chokes squirting it in. then immediately try to start it. if it revs then dies you need to drain the tank and put fresh fuel in.
    neil.

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    I actually put fresh petrol in last week. Still not firing

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    I drained the tank a few months ago due to a leak in the tank

  12. #12
    NSRA member mygasser's Avatar
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    squirt some fesh fuel into the carb throats with the throttle open then try to start it. you may need a bit of throttle to let air in too but if there's spark it'll go, even if only briefly.
    neil.

  13. #13
    NSRA member Blackpopracing's Avatar
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    All you need to run is compression, fuel & spark. If it won't start you are missing one of the three.
    Even if you have too much air coming in it should be trying to start.

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    A few weeks ago I did a compression test 2 pistons lower than the rest but still ran. Got spark on all lines new points and sparking . I’m still thinking it’s too much air . Adobe got 4 double Webber’s ?

  15. #15
    NSRA member Blackpopracing's Avatar
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    If it ran then it should run now. If you think it's too much air then put some gaffer tape over the mouth of each carb mouth to block about 25% or even 50% of the openings. This will effectively be a 'choke' setting. Make sure the tape is stuck good so it does not get sucked into the engine.

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  16. #16
    NSRA member Morris460's Avatar
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    Webber carbs have fixed choke size, they can't suddenly give too much air (the engine takes, carbs don't give), if they were right when fitted they are right today. Having said that you will have "too much air" if you do not have enough fuel.
    As Mark said, fuel and air in roughly the right proportion, compression and a spark at the right time, it should at least try.
    Have you tried a slosh of fuel down the intakes as suggested yet?
    Have you done any work recently that may have changed any of the basic requirements I mentioned.
    Have you checked timing, fuel flow, cam timing? Basics first.
    Layabout.

  17. #17
    Moderator Brizey's Avatar
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    Quote Originally Posted by falcon View Post
    ....This started a year ago at wheels day. Now the engine won’t start. Iv renewed the point/ leads/ plugs/ disi cap/ rotor arm/ coil. Had it running to check with a timing light. Sparking on all plugs plus disi cap.... It used to run but it’s got worse....As I said it started a year ago and has gradually go worse....
    Does the engine fire at all (even on 1 cylinder)?.

    Gradually getting worse over time and despite putting in fresh fuel it still wont start seems to point to the problem not being fuel related to me; unless every single jet in every carb is blocked (very doubtful). If after pouring fuel into the carbs and still getting nothing I would look elsewhere for the problem!. Check the fuel line for blockages, modern fuels can deteriorate and break down the inside of older rubber/fuel lines causing line blockages!, also tank pickup tubes have been know to be blocked by large rust flakes in the tank.

    You say you`ve changed the points but no mention of the condenser!!, was that changed too?. It has been know for a spark to show at the points/plugs when cranking but the spark break`s down under compression in the cylinder when trying to start the motor!.

    Does the motor have a good clean motor to chassis earth?. It has been know for the earth strap to be forgotten and the motor to earth through throttle or choke cables which eventually burn through leaving no earth connection!.
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  18. #18
    Guest falcon's Avatar
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    Thanks I will go through it all again at the weekend thanks for your reply’s

  19. #19
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    Well well I’d put a new condenser in and it was knackered ���� I put the old one in and hey it’s fired up . Still sorting the carbs out but iv got something to work on cheers lads

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