Electrical Issue After Trying Rev Counter

[oliver90owner]

There should be 12V on both sides of the coil if the contact points are open, or 12V on the supply side and very little with the points closed. The coil should be passing 3-4A with the contact points closed.

If there is 1V, with the points closed it may be just the meter or there may be some resistance between the coil and earth.

If the points were open when 1V was measured, the current is being drained (almost) directly to earth. That could be incorrect connection at the points, a shorting pig-tail lead, or a short circuit condenser. The resistance between the condenser connections should provide an initial low resistance, rapidly rising to several Mega Ohms.

[mjh1]

Thanks for that, I'm pretty sure the points were closed but will have another look.
1 think that is quite disturbing is the amount of sparks I get when I connect the spade up to the Distributor. Is that normal?

[StillGotMy1stCar]

You appear to have some unnecessary wires/wiring.
What is the black wire, does it go to that extra capacitor, it seems to disappear in to a loom under the cable tie on the coil. If it just goes to the capacitor it isn’t helping if it is connected to the coil terminal that goes to the distributor, if it was meant to be for interference suppression it should be on the 12V ignition supply terminal of the coil. I’d remove it I doubt it is doing anything.
The white wire on the distributor (pig tail wire) has a poor about to fail crimped connector but also disappears, perhaps to a secret immobiliser switch in the car.
I also noticed another wire that probably doesn’t matter, it comes up from the something bolted to the dynamo, the wire end is bare and dangling waiting for attention near the vacuum advance.


It might be worth starting from scratch.
Make a short pig tail wire to go from the distributor to the coil.
Remove all the wires from the coil.

With your meter find the wire that has the 12V ignition supply (I’m sure that one is connected correctly now).
Fit that to Coil terminal marked with a +
The short lead you just made goes from the – coil terminal to the distributor.
Those are the only wires you need on the coil.

Other to that, the condenser could be faulty, probably not, too much of a coincidence. You can’t reliably test them with a multimeter as they can breakdown with voltage.

If it is fuel related, the pipe from vacuum advance, could be porous or been accidentally disconnected or broken, it might make the fuel/air mixture too weak. That type of braided pipe is known to perish.

Regards John

[mjh1]

Hello StillGotMy1stCAr,
thanks very much for that, very helpful.
The other/spurious wires in there are something for me to tidy and are not connected to anything. I've only owned the car for 5 weeks or so, so need to get into that....

I actually did run a separate/new wire from the - terminal on the coil to the distributor but that didn't work either. As you suspect the 12v to the + terminal of the coil is good and is switched from the ignition (tested with my Multimeter), so the only thing I have not tried is running a new cable from the + battery terminal to the + terminal on the coil.

I do have another set of points and condensor and that will be my next port of call. Is it possible I cooked the condensor, would that show these symptoms?
Thanks for all your help folks, we'll get there!

[myoldjalopy]

Looking back through this thread, you say that the car was "was running sweet prior" to fitting this 'rev counter'. It might help if you tell us exactly what you did to wire it up....

[mjh1]

Hi myoldjalopy,
I ran a temp live from the + on battery to the spade and one side of the rev counter. Then ran the other side of the rev counter to the + on the coil.

[mjh1]

....thinking about it, I'm not sure I removed the switched positive from the ignition to the coil so actually could have had 2 lives to the coil (the proper one and my temp one). Could that have damaged something?

[geoberni]

Well I know nothing about fitting an aftermarket Tacho, it's never been something I've bothered with, but you might find this Mini Forum discussion (from 2016) interesting, since it's about fitting the same Smiths Tacho and the car not starting afterwards....

https://www.theminiforum.co.uk/forums/t ... o-fitting/

At post #3, the Admin puts a link to a diagram, which no longer works, but I believe this is the diagram page he was linking to:
https://spiyda.com/tachometer-wiring

[StillGotMy1stCar]

PM sent

[svenedin]

....thinking about it, I'm not sure I removed the switched positive from the ignition to the coil so actually could have had 2 lives to the coil (the proper one and my temp one). Could that have damaged something?

Yes I am definitely no electrical expert of any kind but as I read your posts it seemed to me that you wired your tacho with 2x live feeds.

Your set up is a bit different from standard in that you have a capacitor across the coil (presumably to reduce radio interference).

I would suggest setting things up in the absolutely standard configuration. Disconnect the capacitor across the coil and wire as per the book (except, if your car has been converted to negative earth in which case follow the book but swap round the coil connections).

See if it then works......If not, try a new condenser inside the distributor.

Stephen

[mjh1]

Yes, 2 lives to the Tacho.
One to the spade to active the tacho coil and the other to the input side of the tacho coil

[StillGotMy1stCar]

I did recommend in my earlier post, removing the extra wiring and starting from scratch.

The reason being, the measured 1V on distributor side of the coil with the points closed is too high, could be the multimeter reading high as pointed put by Rob (Oliver90) or a higher resistance from the extra wiring that disappears presumably to a immobiliser switch or just joined together behind dash from a previously removed Rev counter. So those two wires need to be replaced with a short wire.
I also don’t like the black wire, if it goes to the extra capacitor and it is on the points side of the coil that could make the magnetic field in the coil collapse slower causing a lower HT but for a longer period, equals less spark.
If the black wire doesn’t go to the capacitor it is possibly an alternative way of immobilising the ignition system by shorting out the points with a switch to ground inside the car. So best to remove that wire for now.

Only two wires are needed on the coil, the supply and pig tail to the points.

Doing all the above will improve the spark but be aware the engine may be flooded from a recent failed attempt to start.

It would be interesting to know where the extra wires go, for all we know remotely it could have some home made electronic ignition under the dash.

Regards John

[mjh1]

Hi John,
I did remove all cables from the coil and distributor and run the bare minimum cabling so there is definitely no immobiliser or additional wires going anywhere, also tried with a known good coil from a running car.
I have left the car pretty much for 24 hours in-between attempts so it won't be flooded.
My only hope now is the condenser in the distributor

[myoldjalopy]

The condenser is not the last hope. Could be the points need looking at (I don't like the way the curved points spring looks bent in your picture - it might even be shorting out on the dizzy case), or the dizzy cap may be cracked or tracking, or the spring-loaded carbon bush in the cap is worn or stuck. Could be the rotor, though it *looks* like one of the good ones from the Dizzy Doc. The wire connection from the coil to the low tension insulator and dizzy lead looks a bit suspect too. By the way, it is this low tension lead inside the dizzy that takes the current to the points that I would call the 'pig-tail' lead, rather than the wire from the coil. Usually it is braided, but it is sheathed in plastic in your dizzy, although that shouldn't be causing the non-starting problem you are experiencing.
But I am still puzzled as to why the car was fine before you fitted this rev counter thing, assuming you never touched or damaged the dizzy cap in the process of fitting it.

[svenedin]

Whereabout in the country are you? There may be somebody in your local branch who can sort this out with you pretty quickly......

It seems to be quite limited to what the problem can be.

Stephen

[mjh1]

Hi Stephen, I'm in the north west,
Let me try the condenser 1st, may be as easy as that.

[oliver90owner]

If it is supposedly back to original, look up “Kettering Ignition System” on ‘goggle’. Plenty of simple hits about the simple system that has been around well over one hundred years with virtually no changes/modifications.

[myoldjalopy]

OK, let's try and be methodical. It seems that you have proved the coil is OK. So I would next test the low tension circuit as follows:
Remove the dizzy cap and then remove the wire that runs between the coil and the dizzy and connect a test lamp between these two terminals. With ignition on, turn the engine over slowly with the crank handle and the lamp should turn on and off as the points open and close. If the lamp doesn't turn on and off, there is something wrong in the low tension circuit. See that the points are opening and closing as you turn the engine.
Let us know the outcome of this test and we can go from there.

[mjh1]

Hello all, jut a quick note to say it's sorted. It was the condenser as I suspected.

Thanks to everyone who contributed.

[svenedin]

Glad it is fixed. Condensers failing is a common occurrence these days. Most are very badly and cheaply made in the Far East, despite what they may be branded as. If you search the internet you can find pictures of these condensers opened up with an explanation as to why they fail so easily. Buy condensers from Distributor Doctor. These are made properly. It is a good idea to carry a spare. They take up so little room.

Stephen