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Running unevenly

Discussion in 'Engine & Transmission' started by Basil Bus, Oct 14, 2018 at 6:22 PM.

  1. Basil Bus

    Basil Bus New Member

    I'm having a problem with my 1976 2 Litre Bus and neither of the most respected Kombi mechanics in Hobart have been able to sort it:

    At about 40K in 3rd gear and 50 - 60K in top it runs very unevenly. The feeling is much as if it's missing, although it's not actually missing; there's no dramatic lack in power. Above and below those speeds it runs smoothly. Whether it's accelerating or decelerating doesn't make any difference. It seems to be much better when cold and becomes more noticeable as it warms up. For some reason the unevenness isn't apparent in 2nd. Whatever the cause it has steadily been getting worse over a couple of years.

    I've also been trying to sort some starting issues and in the course of my investigations found that the voltage difference across the two terminals of the coil is usually around 5 Volts. It seems to be quite variable, anywhere between 4.8 and 8 volts but mostly around 5. I've read in a couple of places that it should be at least 9.6V. I've mentioned it to a couple of auto electricians who don't seem to attach much importance to it being so low. Don't know if this is significant, but it's fitted with electronic ignition (not sure what brand, it was years ago).

    Any opinions would be welcome.
  2. oldman

    oldman Super Moderator Staff Member

    Avalon Beach NSW
    Hey Basil...welcome to KC ;)
    More noticeable when warm would indicate, to me based on my experience with similar issue, that you have an electrical resistance issue....
    Try swapping out the HT leads, including the lead from the coil to the dizzy.
    If that doesn’t help, swap the coil out.....they’re not that expensive.
    Also worth checking the carbon block in the dizzy cap itself....can sometimes have a hairline crack...
    Good luck, start simple and work up from there.
    Let us know how you go.....it’s how we all learn here:cool:
    Mordred, David H and tintop like this.
  3. David H

    David H Well-Known Member

    Vacuum canister territory;).
  4. Mordred

    Mordred Super Moderator Staff Member

    Penna, Hobart
    Do you have a standard dizzy you can swap out and try. An electronic dizzy is fine but sometimes when you are trouble shooting it pays to go back to the basics and original set up. No guarantees but might be worth a try.

    I am out near Sorell and should have some bits you can try. PM if your are interested.


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