No spark.

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chrisdebois
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Re: No spark.

Postby chrisdebois » Wed Feb 27, 2019 1:54 pm

Thank you for the continued advice. I have 12 volts going to the new coil now and I have replaced the ht lead but still no spark out of the ht lead when taken out of the distributor.

The answer may be in one of the 2 posts above but I need a break now and will see if the answer is in one of those posts.

Many thanks.

Eta - Yes, have just read the 2 previous posts and I can see I need to do some more tests on the wiring from the switch to the distributor.

myoldjalopy
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Re: No spark.

Postby myoldjalopy » Wed Feb 27, 2019 4:01 pm

If you now have 12v to the SW/+ive coil teminal, the next test is as simmitc suggested - disconnect the CB/-ive wire at the dizzy end and, with ignition on and the King HT lead against the engine, flick the end of the little wire against the body of the car to repeatedly earth/unearth it. This simulates the action of the points so, if the coil is good, it should cause a blue spark at the end of the King HT lead.
If you do prove that the coil is good in this way, I would refit the old dizzy with new points and condensor (from the distributor Doctor, as suggested previously by someone) , check the timing and see if she fires up then.

chrisdebois
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Re: No spark.

Postby chrisdebois » Wed Feb 27, 2019 6:01 pm

I appreciate the advice given so far - thank you.

Can I really go back to basics and ask a question that as a novice would help me understand how things work together.

So - I turn the ignition switch on and I get 12 volts to everywhere like lights, wipers etc and also to the coil.

Now, when I pull the starter knob out and it turns the starter motor over, how does the coil also start firing out the sparks needed to ignite the engine into life?

I can't understand how anything affects the coil when I pull the starter knob out?

Please go easy on me. :)

bufferzone
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Re: No spark.

Postby bufferzone » Wed Feb 27, 2019 7:25 pm

the starter turning the engine causes the distributor rotor to turn which causes the points, or electronic module, to open and close the electrical circuit which causes the coil to create the high voltage needed to fire the sparkplugs. Here is an article that should help you

https://auto.howstuffworks.com/ignition-system3.htm

myoldjalopy
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Re: No spark.

Postby myoldjalopy » Wed Feb 27, 2019 7:42 pm

OK, so when the starter turns the engine over, with ignition on, the revolving engine causes the distributor drive to revolve. The cam in the distributor keeps flicking the points open and closed. The coil itself has two windings of wire - a primary and a secondary one and acts as a small electrical transformer. When the points are open for a split second, the current passing through the coil's primary windings cannot go to earth and the primary windings in the coil cause a very high voltage to build up in the coil's secondary windings - maybe up to 30,000 volts - which is then sent down the King HT lead from the coil to the distributor cap where the rotor arm 'distributes' the spark to each of the four spark plugs in sequence.
When the points close again, the current is earthed through the distributor and the voltage in the coil's secondary windings drops again. Then the cycle continues again.
This all happens very quickly, of course, and the points can open and close more than 100 times a second, to provide a spark to the right plug at exactly the right time.
That's for the points set-up...how an electronic ignition actually works I have no idea, but it will cause the coil to build up and release a high voltage current to spark at the plugs, just as the points set-up does. That is why earthing the disconnected CB wire will cause the King lead to spark (if the coil is good) by doing the job of the points manually.

oliver90owner
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Re: No spark.

Postby oliver90owner » Wed Feb 27, 2019 7:58 pm

The coil is an inductive device, in that when energised it develops a back emf from the windings interacting with the current now flowing - resisting direct current changes. The result of the current flowing causes a magnetic flux (which is actually a form of stored energy) within the coil. Given sufficient time for the coil current to reach its peak, the maximum magnetic flux is simply stored in the coil.

As the current steadily (over a very short time period) reaches a maxiuum, the stored energy now no longer produces a back emf and results in a resistive flow of current through the coil, according to Ohm’s Law.

However, when the coil current reduces to zero (when the contact breaker is opened by the cam fixed onto the distributor drive shaft), the magnetic flux within the inductor (the coil) collapses at a high rate of change, the magnetic field change suddenly changing (from peak to zero), inducies a medium high voltage spike (3-4 hundred volts?) within the coil primary. Because the capacitor, across the contact points, prevents the back emf from discharging (as a spark across the now open points), the flux change creates a very high voltage (several kilovolts) within the secondary coil winding. The distributor directs the energy from this coil to the relevant plug lead and eventually to earth.

The voltage developed, in this part of the coil circuit, is sufficient to jump a relatively large air gap, which it does, being discharged via the HT lead, rotor and plug leads (to earth potential) via the relevant spark plug at precisely the right time to ignite the fuel charge in the combustion chamber. That is how the Ketterig system works and how the spark is directed to each cylinder in turn.

Your point about the 12 volts to the coil is misleading you. There must be a current flowing through the coil to induce the stored magnetic field. The 12 volts should always be present at the coil (with the ignition switch turned on), but current only flows while the points are closed.

The spark is generated by rapidly interrupting that current flow, at the desired timing, to create that very high voltage which is manifested as a spark at each plug in turn.

The Kettering system is basically a simple circuit. It was used for decades, before electronic replacements wrre invented.

simmitc
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Re: No spark.

Postby simmitc » Wed Feb 27, 2019 9:11 pm

I can't understand how anything affects the coil when I pull the starter knob out?
That suggests that you have an earlier car, possibly a 948cc engine? I did ask earlier on for details of the car as it can be important to look at variants. For example, if you pull to start then you do not have a solenoid and therefore advice to check the large terminal on the side of the solenoid would be irrelevant and confusing, yet when you mentioned intermittent 12 volt supply, this is one thning that I was going to suggest. Also, a 1098 engine will usually have a flexible vacuum pipe that is easy to test whereas a 948 will have a metal one that is less easy to suck on, but more likely to leak, which could have been your original problem. Do your HT leads push in to the top of the dizzy cap or go in through the side and are then secured with screws? All subtle differences. They do not affect the theory as explained above, but can alter the way of doing things.

Are you still having other problems, or is everything working other than the spark? Is the engine spnning over nice and fast - is the battery charged or getting a bit tired?

Can you go back over the earlier posts and make sure that you have answeed any questions and reported the reuslts of al tests. Could you post a photo showing the right hand side of the engine bay, ie bulkhead and engine side with coil and distributor.

Don't get disheartened, we all have to learn and start from a poiont of no knowledge. These cars are excellent vehicles to learn on, and you'll be an expert by the time you finish.

COMMANDER
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Re: No spark.

Postby COMMANDER » Wed Mar 06, 2019 6:49 pm

Chrisbebois. You have gone quiet re "no spark". Nothing for a week. Just wondering how you are getting on? Chris

oliver90owner
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Re: No spark.

Postby oliver90owner » Wed Mar 06, 2019 7:38 pm

He has not logged on in the last week.

I might add here, that the starter motor is an unnecessary item in the discussion. The engine should fire, and start, by cranking with the starting handle.

Some engines do not utilise a separate battery and coil, as per the Kettering system - they have an internal coil and magnets which produce a long pulse of generated low voltage current which is interrupted by a set of contact points at the appropriate firing point. Coils may rotate or the magnets might, instead - but the end result is a high tension spark at the plug. The device is called a magneto.

chrisdebois
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Re: No spark.

Postby chrisdebois » Sat Mar 23, 2019 3:16 pm

Apologies for the late reply - I needed to take a break from working on the car for a while. I will be reading your latest posts and hopefully have another look armed with all of the useful information you have given me. Many thanks and I'll report back asap. Best, Chris.

geoberni
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Re: No spark.

Postby geoberni » Tue Mar 26, 2019 11:37 am

Hi
I've been absent from the forums for a few months, so now catching up.

I've had a problem with my Series II Basil not starting. Everything seemed to be right, spinning over nicely and spark at all plugs when they were removed individually and laid on a good earth connection, so I was suspecting fuel age.
Tried some fresh fuel in the carb resevior, but still nothing.

Changed all plugs for new and Varoom! Even starts and runs on only 3 plugs.! Checked the old plugs, Accuspark fancy 3 earth electrode things, unlike the Champion I've just fitted which are conventional N9YC.
All the old plugs seem to have developed a high resistance (around 30-50 ohms) which I can't totally get rid of no matter how much I wire brush the electrodes, which lets them spark, but not well enough. new plugs are a 0 ohm path as you'd expect.

Last year I had a intermittent Ignition problem that had me breakdown on the A1 twice in a matter of weeks. Despite the RAC guys blaming the electronic points, it eventually turned out the be the coil.
This last weekend, I opened up the old coil which I'd put to one side. Here's what I found:
20190324_172852.jpg
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Flimsy soldered connection separated on low voltage connection.


If you're having any problems understanding some of the long descriptions of how the ignition works which have been posted previously, accurate and eloquent though they are, try looking at youtube.
There's plenty of explainer videos there, such as this one: https://www.youtube.com/watch?v=W94iksaQwUo&t=105s
Basil the 1955 series II

Image

chrisdebois
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Re: No spark.

Postby chrisdebois » Sun Apr 07, 2019 2:33 pm

Just a quick update on the non/intermittent sparking. I took my tourer back to the garage which fitted the electronic ignition and when I had it delivered back to me he had put the original points back in. It now runs again and because I had also put a new fuel pump in she is running nicely again.

I wasn't at home when he delivered the car back to me so haven't had a chance to discuss it with him. Not sure how to approach the matter of the £100 he charged to source and fit the electronic ignition?

Anyway all is well now and I much appreciate all of the detailed replies many of you gave me when I was asking for help.

All the best, Chris.😊

pgp001
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Re: No spark.

Postby pgp001 » Sun Apr 07, 2019 3:01 pm

Hi

I would be interested to know which make of electronic ignition you have that has failed please.
It sounds like it should go back to the manufacturer for replacement if it is not 12 months old.

Thanks
Phil

cococola
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Re: No spark.

Postby cococola » Sun Apr 07, 2019 5:30 pm

This is similar to my problem that I had on my Traveller, I have had 2 failures on Accuspark electronic ignition units and when it again failed last sunday I decided to revert back to contacts and condenser. My car has done approx 80 miles this week with no break down and I feel that the car runs better than it did previously.
I have been in contact with Accuspark and they wont exchange the faulty unit as it has already been replaced under warranty (even though the replacement lasted 7 weeks and the first 8 months) I did check the coil etc to be sure that this isn't a result of the failures with nothing found.
My convertible has the Accuspark unit fitted 3 years ago with one failed unit so far and they are not as reliable as I hoped they were (unless I'm unlucky...3 times total) :( :-?
Spare contacts and condenser in the convertible glove box at the ready. :D
Morris Minors..... such fun :D

SteveClem
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Re: No spark.

Postby SteveClem » Sun Apr 07, 2019 7:16 pm

Sounds like you have been unlucky. I have electronic ignition on 3 cars and all has been fine. Didn't work on the Beetle though, so reverted to points etc.

COMMANDER
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Re: No spark.

Postby COMMANDER » Wed May 01, 2019 3:00 pm

Points and condenser every time. Had electronic units fail twice on my MGB. Reverted to points on the second failure and I'm sure the car ran better.


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