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surges while cruising

Discussion in 'Engine & Transmission' started by hasafro, Aug 17, 2008.

  1. hasafro

    hasafro New Member

    Messages:
    75
    Location:
    Warragul, Melbourne
    surges while cruising - FIXED!

    Wondering if anyone has an idea what might be going on with my 2 litre. When I'm cruising the engine seems to surge like it's missing or something. I've just had both heads replaced and clearance is fine, changed points and plugs, leads are fine too. The only other option is carbies, the needles seems fine and there doesn't appear to be any blockages. She has plenty of power so the compression is good but she just seems to get the yips when cruising and sometimes bogs down when I sink the boot in for a quick take off. I'm gonna run a carby cleaner through it this week (any suggestions on brand?) but other than that I don't know what else. It's not bad fuel either as I've filled up a few times from different servos.
    Anyone have an idea what it might be?:umm:
     
    Last edited: Oct 23, 2008
  2. kombidaze

    kombidaze Member

    Messages:
    466
    Location:
    Uki NSW
    i'd may be looking at the distributor is the vacuum line from the carby connected to the vacuum can if it bogs down when you accelerate then maybe your accelerator pumps are supplying to much fuel they can be backed off depending on your carbies there is either a nut or a cotter pin and three holes in the arm either back of the nuts so there is only very little threat showing or put the pin in the most outside hole the other posibility with the distributor is that the centrifugal advance is all gunked up and the weights are not moving as they should, there is and inspection hole with a plastic cover on the side of the distributor you may be able to squirt some inox lubricant in there and loosen up the weights. its also possible that you carbies are not getting enough fuel it could be the fuel pump it could be the needle and seats and it could be the float level
    best i can come up with
    john
     
  3. jman

    jman New Member

    Messages:
    583
    Location:
    Hobart
    Tune up

    Your carbies could be slightly out of sync.
    One carby may have it's throttle a tad more open than the other. This can cause surging at low revs or flat spots when lightly accelerating.
    can be tune with a Length of Hose, a Synchrometer or a Mechanic. I'd suggest one of the first two.
    Cheers, J
     
  4. Bay_Buddha

    Bay_Buddha Member

    Messages:
    397
    Location:
    Berowra Heights,North of Sydney
  5. hasafro

    hasafro New Member

    Messages:
    75
    Location:
    Warragul, Melbourne
    Thanks for your input guys. I've checked vacuum lines and they're all good so I don't think its related to those. John what is inox lub and would a squirt of WD40 do the job? Jman how do you sync using a bit of hose? The bogging down isn't really a problem and only happens rarely, it's more the surging at cruising speed that I'm trying to figure out, my fuel economy has taken a beating too and is now around 16L/100km. When I accelerate it feels fine but when it drops back to cruising (ie. when the balance between car and engine are about equal) it starts to surge a bit. I checked the plugs today and they're all a little black but not caked up and not too bad after 700km, and one side isn't any worse than the other. My only thoughts are fuel pump, carbies, or faulty electrics but I have no idea on how to determine which one it is without just replacing them. Does anyone know an easy way of diagnosing these parts without pulling them apart too much, or any other suggestions.
    Cheers
    Storky
     
  6. jman

    jman New Member

    Messages:
    583
    Location:
    Hobart
    Old School Mechanics Trick #1
    with approx 2 foot of fuel line or smaller hose, engine idling one end of hose in your best ear hold the other end in the centre of the mouth of each Carb. The hissing pitch that you hear should be the same at each. adjust if necessary. higher pitch is open more than other and vise-versa.
     
  7. hasafro

    hasafro New Member

    Messages:
    75
    Location:
    Warragul, Melbourne
    Thanks J,
    Will give that a go at some stage. Don't s'pose you have a diagnositic suggestion for fuel pump or alt
     
  8. jman

    jman New Member

    Messages:
    583
    Location:
    Hobart
    What's up with your Fuel pump? Electric or Mechanical? If your getting fuel to your Carbies and your engine actually runs, then your pump is fine.

    Good luck. Let us know how ya go with the bit of hose in ya ear. Ha ha.
    It does actually work. If you have good hearing it can be more accurate than those expensive Sync'ing Tools.
    [​IMG]
     
  9. kommodius

    kommodius Active Member

    My brother (then a medical student) used to synch carbs with a stethascope & man, could he tune 'em up!! Like a choir!!

    Ray & da Boyz
     
  10. hasafro

    hasafro New Member

    Messages:
    75
    Location:
    Warragul, Melbourne
    Jman, tried your ear tuning trick, didn't fix my problem but certainly improved the power and economy. I've checked my alternator and I'm getting full charge and good spark so the only things I can think of are re-checking vacuum lines or something really serious.
     
  11. emby

    emby Active Member

    Messages:
    2,006
    Location:
    Wights Mountain, QLD
    I hope you find what it is.

    And when you do can you let us know what it was and how you fixed it?
     
  12. hasafro

    hasafro New Member

    Messages:
    75
    Location:
    Warragul, Melbourne
    I'm one very happy and excited kombi driver again!!!
    After a week at the mechanics my baby is back to normal again!!!
    We tried everything, checked vacuum hoses, replaced vacuum hoses, fitted new carby jets, fitted new carbies, tried a new dizzy, fitted a new coil, changed plugs leads and points, refurbished the fuel pump, but still no joy! I was frustrated and my mechanic was perplexed... But finally after all this we found the source of the problem, dodgy idle jets! He fitted new ones and she runs like a dream. And now that she has new heads, new gearbox, new dizzy and an overhauled fuel pump she runs better than ever!!!
    Now I know he doesn't need the advertising as he's always flat out but a big hats off to Dean at Volkspower, he did and always does do a fantastic job and he's currently my hero, although admittedly that may all change when he hands me the bill.
    So there you go, something else to add to the list of possible causes of rough performance.
     
  13. hasafro

    hasafro New Member

    Messages:
    75
    Location:
    Warragul, Melbourne
    A week on and still going strong. My old dizzy has been refitted and she's still working perfectly. The old idle jets were removed and replaced with new ones and the electronic control disabled. She runs smooth as and has improved fuel economy.
     
  14. kommodius

    kommodius Active Member

    Do you mean the cut-off jets?? Or is it some other bit of electrickery thing?

    Ray & da Boyz
     
    Last edited: Oct 23, 2008

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