anyone familiar with weber 34 ict carbs ?

Discussion in 'Mech Tech' started by bezy, Apr 22, 2019.

  1. hi all.

    we have a baywindow with twin weber carbs fitted, all was running well until recently we broke down after lots of hesitation and jumping the van stopped and wouldn't start.

    I managed to get it started again after a while then drove straight home.

    I thought it could be a fuel issue, and replaced the fuel pump and filters, but after a test run it started to happen again so I came straight home.

    fuel is getting to the carbs and it idles fine, but on driving it jumps and hesitates then sometimes conks out, for a while.

    I think the jets could be blocked?

    I am wondering if anyone knows how to remove the jets from these carbs? so they can be cleaned,
    Or if anyone is in the know with these, and are able to assist I could pay the going rate, we are in Haverhill Suffolk.

    really stuck with this now and at the moment don't trust the van to drive it anywhere.

    any help or advice appreciated,

    kind regards mike
     
  2. It's 10 times more likely to be ignition related than fuel, what dizzy set up have you got? Electronic or points/condenser?
     
    Dubs and 72devon like this.
  3. If it is carbs I’d call Wilshers at Royston & as if they can help. The father did my carb tuning/ rolling-road and really knows what he’s about. Not sure if he is still there but if so that’s where I’d go.
    http://www.wilshers-garages.com/default.asp


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  4. Think this is correct.
     
  5. ^this
     
    72devon likes this.
  6. Hi everyone, thanks for your replies. I think it's electronic ignition now.

    I hope I can get it sorted, missing out already on this lovely weather

    Engine rebuilt only a few years ago.
     

    Attached Files:

  7. Pics do say a 1000 words.
     

  8. Ah, just read this again and it may well be your electronic ignition module. I had a similar problem although it only happened after the van had been running for an hour or two: it would run fine splatter run run for a few minutes then cut out completely and not restart. If left for several hours (i.e. it had cooled down) it would start just fineAnd so on. It’s probably worthwhile changing over that module as they are not very expensive. I thought electronics would die for work but apparently not


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    Lasty likes this.
  9. Thanks for message, that sounds exactly like our fault , I could give it a go,

    Now , where abouts is the electronic ignition module ?
     
  10. Inside your dizzy,do you have a black and a red wire coming out of dizzy.
     
    SeanOC likes this.
  11. Yes I'm pretty sure we do.
     
  12. Not a green wire.
     
  13. SeanOC likes this.
  14. The modules can overheat and produce wierd effects.


    The other thing that happens with Weber carburettors is the fuel metering valves in the float chambers wear and leak.

    This gives the symptom that all the time you are driving it hard it runs OK. Then you get to a 30 limit slightly downhill (no load on engine doesnt need much fuel) and it judders to a halt. This is when the petrol runs out of the float chamber and into the manifold through the overflow , and it makes the engine run rich.

    It will start eventually if you hold your foot on the throttle and crank for a lifetime without stomping the pedal.. eventually the petrol evaporates and the engine can run again. Or go into Costas for a latte and a toasted teacake...and it will magically start without trouble..


    Another symptom of the metering needle valve leak is that your oil level stops going down and the engine ends up lubricated by petrol and then stopping by siezing up. The oil smells of petrol in that case.

    Too much fuel pressure from a new fuel pump can also cause the over fuelling while running but that one does not contaminate the oil.
     
    Last edited: Apr 22, 2019
  15. Do you not have a spare points dizzy to drop in and see if it makes a change.
     
  16. Or swap out with a set of points and a condenser cheap option.
     
  17. Dubs

    Dubs Sponsor

    Whs /\

    Stick a set of points in and see if the problem disappears..
     
    snotty and 72devon like this.
  18. Thanks everybody for your help with this. This gives us some more things to try.

    Just Like someone said earlier, it can drive fine for about an hour then suddenly jumps and hesitates then conks out completely.

    Leave it a while and it will drive again.
     
  19. What fuel pump do you have? These carbs need very low fuel pressure to run right, factory elec pump will be way too much pressure for them to cope with
     

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