Please help backfire running rough mystery

Discussion in 'Bay Tech Clinic' started by jimmybay, Feb 25, 2012.

  1. jimmybay

    jimmybay New Member

    Messages:
    267
    Location:
    roxby downs sa
    Ok problem is back :/
    Engine was idling high after the problem was fixed.
    Changed out sparkplugs idle dropped right down and now it's dying under load
    Carbs may be on the way out.
    Or burning out leads and coil? What would cause this?
    I'm bloody close to traveling home and putting the 2l in that I have but that means stopping our trip and working for a few more months.
    Can't get into a mechanic till Tuesday. Hopefully he can solve this prob!!!
     
  2. Syncro27

    Syncro27 Well-Known Member

    Messages:
    5,716
    Location:
    Terrigal, NSW Central Coast
    Did you knock anything on the carbys when you replaced the spark plugs?

    Backfiring is a timing issue and therefore usually relates to the dizzy and the points or in your case the electronic ignition.

    I would put the points and condenser back in as Kai suggested. you may need to adjust them every now and then but its an easy job to adjust the points once they are back in.

    I have heard a few of those EI set ups have been a complete failure for others.
     
  3. Bennyharp

    Bennyharp Member

    Messages:
    308
    Location:
    Eltham
  4. ttmck

    ttmck Super Moderator Staff Member

    Messages:
    2,733
    Location:
    Hallett Cove STH AUS
    In the post click on the link the second picture shows a goldy braided wire inside the distributor this is an earth lead for the base plate you may have a bad connection on this wire .
     
  5. passin through

    passin through New Member

    Messages:
    32
    Location:
    Armidale
    Hi, did you ever find out what was causing this problem? As mine has just started doing it.
     
  6. oldman

    oldman Super Moderator Staff Member

    Messages:
    7,720
    Location:
    Avalon Beach NSW
    Go right over your carb/s closely. Check that there are no loose welsh plugs. I once had one work loose on the L/H carb on my 2ltr. causing the engine to idle at high revs. - (engine getting way too much air.) Easy enough fix. - carb. top off pein the plug back in & seal off with heat resistant silicone just to be sure. Hasn't missed a beat since. Hope it is that simple - you must be tearing your hair out by now......Gotta use a process of elimination. Check each component really thoroughly before moving on to the next option. Cheers, Mark
     
    bern likes this.
  7. passin through

    passin through New Member

    Messages:
    32
    Location:
    Armidale
    Let us now what the problem was when you get it fixed. As I have the same problem. The old girl is sitting on the side of the road and won't go.
     
  8. jimmybay

    jimmybay New Member

    Messages:
    267
    Location:
    roxby downs sa
    High idle was due to carb adjustment must have bumped it when changing plugs. The bus is running pretty much spot on just a little rough on cold starts. Changed over to another dizzy with points did nothing :/ I replaced the plugs and leads again as the main coil lead as the resistance was reading a bit high( brand new lead must have been on it's way out!! ) I think the carbs may be due for a tidy up or a retune as still fowling a bit on startup. Sorry probably doesn't help much.
     
    Last edited: Jun 26, 2012
  9. Bretto

    Bretto New Member

    Messages:
    2
    Location:
    Sunshine Coast
    I have a very similar problem with my 74 Bay. Intermittent rough running, back firing. Happens when cold and hot, low speeds and high speeds (well 100kmph).
    I have changed the plugs, leads, points, dizzy cap, and coil. Still no change.
    Becoming very frustrating!

    Anymore ideas???
     
  10. 76kampa

    76kampa Active Member

    Messages:
    105
    Location:
    Perth
    I found my problem fixed by leaning out the carby and going for a very long drive.

    Make sure you check the Rotor as well :) that what what my problem was and is not an item that I would have thought would be a problem.

    As stated a few times make sure the engine is earthed decently and the timing is set right (and don't play with/change it out of frustration)
     
    bern likes this.
  11. cbus

    cbus Well-Known Member

    Messages:
    10,646
    Location:
    sunshine coast
    Condenser ?
     
    StevieVW likes this.
  12. Barry

    Barry Well-Known Member

    Messages:
    2,342
    Location:
    Abbotsford NSW
    Have you done the basics?

    FULL tune, valves set, timing set, dwell set?

    Has it ever run properly?
    Or is this a fixer upper that you have just acquired?
     
    StevieVW and cbus like this.
  13. bern

    bern Active Member

    Messages:
    825
    Location:
    Fernvale, Qld
    Yes Mark, just read the thread and remember fixing a probl, like it with a 2 cent coin!!....can post one to anyone who lost their weslh plug in the back of left carb lol...

    simply just borrow a dizzy from a twinport 1600 up to2Litre mtr and test - see if any change...or have one posted....via wanted ad or suppliers
     
  14. bern

    bern Active Member

    Messages:
    825
    Location:
    Fernvale, Qld
    see my previous post above also check ROTOR & fuel
    and I have had 1 plug foul (well actually die)...
     

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