v8 dizzy tests

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S

skintnow

Active Member
Posts
160
Location
kimbolton cambridgeshire
Hi all
rangie is officialy dead
are there any test proceedures for the dizzy
out in it yesterday it backfired about three times then cut out (it came back on the back of a breakdown wagon :mad: ) it cranks but no spark new cap new rotor arm new coil so really down to dizzy just wondered are there any known test proceedures to confirm this
its a 3.9 efi (lovely bl--dy annoying heap of beauty:) )
thanks
 
Yeah it is , I think its about £40 , but you can get a recon dizzy off ebay with a 2 year warrnty for £65 so you have to debate if its worth it , I recon to fit it the dizzy has to come out anyway,its certainly alot easier.

Regarding the backfire, I am not so sure, could be-its the only ignition part you havent replaced so far!
 
hi kev
carried out the tests you listed appears the amp had blown while i had the dizzy out tested the internal resistance of the dizzy all well within spec but still no spark and no go so to date we have voltage in all the right places new coil new cap leads rotor and amp a dizzy that measures up so anyone got a spare can of petrol (not to put in the tank but to pour over the car)
 
skintnow said:
hi kev
carried out the tests you listed appears the amp had blown while i had the dizzy out tested the internal resistance of the dizzy all well within spec but still no spark quote]

Replace the ignition amplifier and all should be well (hopefully). Just remember to check the air gap is right between reluctor and pick up in the dizzy and while you're at it, make sure the vac and mechanical advance are both working. I don't know if you've taken the dizzy out before but it can be a bit of a fiddle getting it back in the right place. You did mark it before you took it out didn't you?:eek:

Make sure you set your ignition timing correctly!!

Good luck.
Click to expand...
 
BTW when you re-assemble it all make sure you push the connector plug on the amplifier very firmly - I made the mistake of quickly putting it on and unsurprisingly it came off leaving me stranded. A rather embarrasing breakdown that one but luckily I was very close to home and was probably the quickest fix I've ever done!
 
hi kev
yes i took the dizzy out and marked everything (even a few things i didnt need to )the dizzy had an amp fitted with three pins and a multiplug with only two pins and the centre one missing i have fitted the two pin version back in this should not make any difference should it also when i had the dizy out i measured the resistance across the two terminals of the dizzy with the amp off if i then turned the dizzy by hand slowly it would go open circuit i assumed this is the switching for the amp am i correct ?
guess i will be back out there tomorrow with the multimeter testing again :(
 
ok been out there this morning with the multimeter carrying out the tests kev described in the misfire post
amplifier test for switching
ign off battery + to coil - should show 0v mine shows 12 v
ign on battery + to coil - should show 0v mine shows 12 v
its a brand new amplifier and the dizzy tests out ok
suspected bad connection so made up 2 new leads to amp still same results

HELP
 
Sounds like you have an earth problem with your coil.

Think about it. Battery +12v to coil Negative is what you are testing.

With ignition off, there should be nothing there because the coil shouldn't be grounded on the LT side.

With the ignition on, you are testing the voltage from battery +12v to the now energised coil (12v) so the difference is zero.

Hope that makes sense.
 
sorry guys havent had a chance to get out and have a look for a couple of days work got in the way of tinkering (damned inconvienient government should put a stop to that)
but my haynes turned up today just to update car has had a new coil fitted still ran new cap new leads new rotor arm and still ran
driving along the other day and she backfired a couple of times lost all power and died (luckily outside a pub ) so called breakdown out they tested spark and no spark so next obvious choice was amplifier fitted new amp still no joy carried out tests as supplied by kev (many thanks for those ) and results are listed on previous page so all thoughts are appreciated
next time for tinkering is saturday afternoon :confused::frusty:
 
Never did get to the bottom of why mine lost spark when mechanic was working on it, it just came back on its own, £300 later mind you, with differnt mechanic working on it and its been ok since.:confused:
 
MMMMM.......!

The ignition system is not complicated. I think the next suggestion is gonna smart a bit but Strip, check, clean and rebuild the ignition system. Make sure you do it by the book, also make sure everything is connected, all grounds are good and that you have power where and when you are supposed to have power.

When all is said and done, if you have an ignition switched live energising the coil and the ignition amp, either the ignition amp is not switching or the pick up in the dizzy has a fault and is not generating the signal to trigger the amp to make the coil field collapse to induce the spark. Take it back to bare bones basics is the only sugestion I have left.
 
its fixed and now sweet and such a simple fault in the end
positive terminal to coil although showed 12 v as it should when tested with a meter when any load was put on it it broke down to 0 stripped and cleaned it replaced terminal reset ign timing and adjusted the airflow as advised by kev and away we go
many thanks to all on here who have been very patient with me

now wheres the snow or mud :):)
 
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