Carburetor leaking - never seen this before

Discussion in 'Bay Tech Clinic' started by greenie, Apr 1, 2018.

  1. greenie

    greenie Member

    Messages:
    44
    Location:
    Sunshine Coast
    Hi

    We are currently testing some old carbies (Empi EPC34), have done a rebuild kit on them and tested on the engine - appear to be the perfect fit for the engine (after a bit of tuning etc) and was hoping to use them.

    However, they are leaking AFTER the engine is turned off (not for at least 10 mins for one and 25 mins for the other side). On the workshop bench, we put a bit of fuel in the bowl with top of carby off, no leak, put the top of the carby on and then a few seconds later, its like a syphon effect, with fuel coming out of the bowl and out of the bottom of the carby.

    Have a look at the video we did of it (you might have to copy and paste it).



    Never seen a leak on a carby that only happens such a long time after the engine is turned off.

    Thanks
     
  2. greenie

    greenie Member

    Messages:
    44
    Location:
    Sunshine Coast
    Thanks, trying lots of different things at the moment - this headache we have is definately NOT an april fools joke...
     
  3. kombiing

    kombiing Member

    Messages:
    35
    Location:
    Lower hunter
    Do you have an electric fuel pump? And a fuel pressure regulator? It maybe that active and residual fuel pressure causing problems
     
  4. Barry

    Barry Well-Known Member

    Messages:
    2,432
    Location:
    Abbotsford NSW
    My guess is that is your problem - EMPI
    Their quality "can be" utter rubbish
    When they released the HPMX Weber copies they had similar problems.
    Fuel just disappeared

    My guess is you have hairline cracks in there that are difficult to see

    By a proper carb is my answer
     
    Poptop likes this.
  5. greenie

    greenie Member

    Messages:
    44
    Location:
    Sunshine Coast
    We have a mechanical fuel pump. We have just put a fuel pressure regulator on and turned it right down and instead of 10-25 mins after, it now starts leaking 2-3 HOURS after the engine is turned off. And it is a very steady drip, not just a drop or two, it is like it is emptying out the whole carby.

    If it was hairline cracks, I would think it would leak immediately, but the time delay is what is totally confusing us now. Since putting on the regulator, it takes a lot longer for it to start leaking...

    Not sure if we should buy a new carby or if this is something else causing this...

    Has anyone had that before?
     
  6. Wayne murray

    Wayne murray Well-Known Member

    Messages:
    1,670
    Location:
    Seven hills
    Have you replaced the needed and seat .Checked the float hasn't got a hole in it and is full of fuel in the float. Does the float move freely(bent slight out of a lineament ) as if it is rubbing as it moves up and down.
     
    greenie likes this.
  7. greenie

    greenie Member

    Messages:
    44
    Location:
    Sunshine Coast
    Hi Wayne, new needle and seat, float looks fine, can't find a hole and "floats", seems to move free enough...
     
  8. David H

    David H Well-Known Member

    Messages:
    2,963
    Location:
    newcastle
    So reg has slowed the time to leakage. Tank is above carbs & gravity works well:p. There must be a syphon point.
    Now you've just got to find it;). Prob in carb as Wayne says.
    I'd be trying a different carbie!
    Cheers
     
    Last edited: Apr 11, 2018
    greenie and Wayne murray like this.
  9. rstucke

    rstucke Well-Known Member

    Messages:
    559
    Location:
    Wamberal NSW AUS
    blocked idle air bleeds will cause carbies to syphon out.
     
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  10. David H

    David H Well-Known Member

    Messages:
    2,963
    Location:
    newcastle
    Damn glad for F/I. I used to think F/I was fussy but now I know carbs are worse:p:D.
    Cheers
     
  11. rstucke

    rstucke Well-Known Member

    Messages:
    559
    Location:
    Wamberal NSW AUS
    find the idle air bleeds and blow them out with compressed air.
    Understand how syphoning can occur from this basic picture if the idle air bleed is blocked

    P4120101.JPG
     
    David H likes this.
  12. 1500king

    1500king Well-Known Member

    Messages:
    1,517
    Location:
    Adelaide, SA
    Float bowl is over-full. The fuel is overflowing into the main nozzle.
     
  13. greenie

    greenie Member

    Messages:
    44
    Location:
    Sunshine Coast
    Hi 1500king, definately not too full, only a third full at most. :(
     
  14. greenie

    greenie Member

    Messages:
    44
    Location:
    Sunshine Coast
    Shall try this! Have tried everything else....
     

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