Accuspark Failure

Discussion in 'Mech Tech' started by scottsykes, Jul 1, 2015.

  1. Filled up with fuel Sunday and then it wouldn't start, eventually she fired but only a few yards it began backfiring and died.
    AA came, no spark, coil is fine but not switching.
    Dissy is brand new, is it possible that the Accuspark magic eye has failed??
    I've ordered another..... It was all going so well lol
     
  2. I've had a accuspark go in a previous bus too so don't rule it out.. mine went after a year and a bit mind you..

    Or at least im 99.99% it was the accuspark as I fitted a new one and all worked fine again :)
     
  3. Cool, mine should be here today, looks new but anything can fail I suppose
     
  4. Just changed it and it still won't fire!
     
  5. check for a spark at two opposing HT leads to verify the module/cap/rotor/coil are OK....if no spark, disconnect the king lead and ground it wherever you can...if this sparks, the problem lies in the cap/rotor....probably the rotor
     
  6. never assume that brand new is OK - rotor arms are particularly suspect these days
     
  7. A test lamp won't work in the same way as it would with points so "not switching" might be a bit of a misdiagnosis.

    Where have you checked for a spark? Follow @vanorak's advice.
     
  8. Yeah and there was none, do you think coil?
     
  9. To test coil, pull central HT lead off the dizzy (the one that comes from the coil), hold it roughly 1/8" away from earth i.e. engine block (insulate yourself!) and have someone turn the key. You want a blue spark. Yellow/Orange means the coil is on it's way out. No spark here and the coil is the culprit (as long as it's getting 12V).
     
    vanorak likes this.
  10. Wi try in a bit guys cheers, when it turns its back firing slightly, it that cos I moved dissy slightly?
     
  11. If it's backfiring you must be getting a spark somewhere.

    Maybe you've just checked at one plug and not getting anything?
     
  12. Put diesel in it ?
     
    scottsykes and zed like this.
  13. Nooooo! She's running again!! Yay!!! It must have been the Accuspark,I put dissy in 180 out, fired first time and running sweet again... Very happy
     
  14. So new Accuspark works (with dizzy in right place) but old doesn't?
     
  15. Yep, sweet as a nut
     
  16. How old was it and did they replace it ok?
     
  17. mikedjames

    mikedjames Supporter

    With accuspark points replacement it does not fire unless the engine is turning or the magnets in the distributor are moving.

    So rough setting up static is done by setting the engine at 7.5 btdc and waggling the rotor arm and checking it fires.
    Then get it started then time it properly.
    nightmare if you need to do a new cam hardening run and the timing is too far off ..
     
  18. It was already on when I bought it, it did have a new engine 1000 miles ago so it's probably not old, I just bought another didn't try for an exchange..
     
  19. article here is for BMC engines but works fine for aircooled with electronic ignition:

    Static timing with electronic ignition

    Obviously, with the electronic set up you can't use methods which detect when the points open. The way to do go about static timing under these circumstances is:

    1. Mark the current distributor position, marking both distributor to clamp and clamp to block. This will allow you to reference whether the timing was out, and if so by how much. On the Lucas distributors used for XPAG, A,B and C series engines, 1mm at the distributor base is 6 deg on the crank so make sure the marks are clear!

    2. Set the crankshaft to the required static timing point with the rotor pointing towards no 1 plug lead

    3. Refit the distributor cap.

    4. Either attach your strobe light to no 1 plug lead, or (if you don't have a light) remove no 1 plug lead and fit a spare spark plug to it (with the body of the plug suitably grounded to the engine)

    5. Find the approximate position for the distributor by rotating the whole distributor fairly rapidly clockwise (ie opposite to the way to the rotor turns) until a spark appears (be it at the light or at the spare plug). You may have to rotate the distributor anticlockwise 20 or 30 deg first before doing so in order to ensure the timed position is covered on the clockwise sweep.

    6. Having noted the approximate position, refine the process by using a smaller angle of sweep centred on the approximate position and moving the distributor as slowly as it is possible to do yet still get a spark.

    7. Tighten the distributor clamp.
    This process may end up with a degree or two of extra advance. In engines with timing marks visible from the top, I would then check by rotating the crank and seeing what the pointers read when the spark appeared. However, this is a luxury for engines which still have the timing marks underneath! In any event, the right maximum advance usually results in more advance at static on a worn distributor.
     
  20. As I'm in pedant mode now, I'd point out than you can static time electronic ignition modules in exactly the same way as points, as they only have a transistor replacing the contact breakers. But...if the ignition module has a feature that senses when the engine's not turning - as it seems the Accuspark units do - then you'll have to do it with a strobe. A bog-standard Pertronix or other units you can time statically, as per breakers.
     
    tommygoldy, vanorak and Pickles like this.

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