Ignition problems, no spark

[Casiofi]

My minor had been intermittently stuttering while accelerating, though generally fine at constant speeds, for about a week. Then yesterday, the engine suddenly died, and I pathetically rolled into a conveniently placed layby. I thought it was overheating, but when I eventually got her home by means of a Landrover and a tow rope I found that there was no spark. So I have new points & condenser, rotor arm, dizzy cap, HT leads and spark plugs on their way as most of them look pretty jaded, and I was planning on changing them soon anyway. This morning I went out and cleaned the rotor arm, checked the points and plugs were set correctly, then went to check the spark again and she fired up! For all of 3 seconds before being back to square one. My dad suggested testing the coil by taking the lead from the coil to the dizzy off at the dizzy end and checking it as if it were a spark plug. This didn't give a spark, which as I understand it means that the problem could lie in the coil? Anyone got any ideas?

[The vast minority]

how far away did you hold the coil lead from an earth?
Al

[panky]

I did have a very similar problem on a Viva years ago, it happened just after a full service. Took me ages to find that the shiny new condenser was faulty - popped the old one back in and vroooom.

[Casiofi]

how far away did you hold the coil lead from an earth?
Al

I varied the height from touching the metal to about 1/4" away from, no spark at any height

I did have a very similar problem on a Viva years ago, it happened just after a full service. Took me ages to find that the shiny new condenser was faulty - popped the old one back in and vroooom.

I have heard of quite a few bad condensers right out of the box , so I bought three sets with the hope that at least one would work! I'm hoping they'll arrive tomorrow so I can start replacing bits!


I've ordered a new coil, just so I can rule that out if it still won't go. Thanks for the help, I'll update tomorrow and let you know if the problem's fixed!

[The vast minority]

As long as you are sure the metal was earthed, if you got no spark then the coil ( or the lead) ist probably defective but don't forget to other connections to the coil and dizzy. a simple spade connector has been known to become an insulator with corrosion under the plastic crimp. Take them off and do a continuity test.


Al

[Casiofi]

As long as you are sure the metal was earthed, if you got no spark then the coil ( or the lead) ist probably defective but don't forget to other connections to the coil and dizzy. a simple spade connector has been known to become an insulator with corrosion under the plastic crimp. Take them off and do a continuity test.


Al

That is a fair point! Not long ago I redid the female spade connector on the dizzy, but I'll give them all a look over and clean before I try fitting new parts, just to be sure. Thanks!

[bmcecosse]

Oh dear - it's NEVER the coil!!!!!! Just because there is no spark from the king lead - doesn't mean a faulty coil! It means there is no Low tension make/break taking place !! Is there any power at the coil - check both sides - with the lead from coil to dizzy disconnected.

[Casiofi]

Oh dear - it's NEVER the coil!!!!!! Just because there is no spark from the king lead - doesn't mean a faulty coil! It means there is no Low tension make/break taking place !! Is there any power at the coil - check both sides - with the lead from coil to dizzy disconnected.

I had a feeling that would be mentioned! I shan't rule it out as it looks reasonably new (only had the car a year) and I know that modern Lucas parts aren't quite as bulletproof as they used to be. But proper tests will be carried out tomorrow morning!

[alexmcguffie]

Assuming all the LT wiring is ok then I'd change the condensor first after checking the centre 'plunger' is still in the distributor cap. Due to their construction they don't last for ever. They generally cause a short circuit when they fail which effectively bypasses the points. Boefore you do that though, worth taking the distributor cap off and with the ignition on open and close the points with your finger nail and see if there's a small spark across them (there should be). That will prove the condensor, points, coil primary side and LT wiring are ok.

[Casiofi]

So the bits arrived today! I went out and checked the coil, there was voltage going into it through the spade connectors. I tried firing it up and staight up it it ran for 20 seconds or so and then died - no spark again, still voltage at the coil. So I changed and set the points, put in a new condenser, changed the dizzy cap and HT leads, but still no joy.

Assuming all the LT wiring is ok then I'd change the condensor first after checking the centre 'plunger' is still in the distributor cap. Due to their construction they don't last for ever. They generally cause a short circuit when they fail which effectively bypasses the points. Boefore you do that though, worth taking the distributor cap off and with the ignition on open and close the points with your finger nail and see if there's a small spark across them (there should be). That will prove the condensor, points, coil primary side and LT wiring are ok.

The centre plunger in my old cap looked pretty worn (along with the HT leads!) so I replaced it. I tried opening and closing the points manually with the ignition on, both with the old set and after they'd been replaced, and couldn't see a spark either time So I guess it's time to do some tests on the coil/wiring!

[alexmcguffie]

If you have a multimeter you can connect it between an earth point and the connector coming out of the distributor from the points. With the ignition off, open and close the points again by hand and see what resistance the meter shows. Ideally 0 ohms with points closed and infinite with them open. If not, check that the stud that the condensor and coil lead connect to is assembled correctly on the points. They should both be between in insulator and spring as indicated on the photo.[frame][/frame]

[bmcecosse]

You shouldn't have changed so many things at the one time! If it's a NEW coil - then it could well have failed.......the 'never' only applies to original coils. new coils can fail at any time - especially if they are wrongly specified for the voltage... Running for 20 seconds - you sure it's not fuel.......

[Casiofi]

You shouldn't have changed so many things at the one time! If it's a NEW coil - then it could well have failed.......the 'never' only applies to original coils. new coils can fail at any time - especially if they are wrongly specified for the voltage... Running for 20 seconds - you sure it's not fuel.......

I changed them one at a time, starting with rotor arm, then points & condenser, then HT leads and dizzy cap. Spent about 3 hours this morning just changing out each part individually, so each new part has been tried with the old setup. Pretty sure it isn't fuel, though the thought did cross my mind, there still isn't any spark when I check...

If you have a multimeter you can connect it between an earth point and the connector coming out of the distributor from the points. With the ignition off, open and close the points again by hand and see what resistance the meter shows. Ideally 0 ohms with points closed and infinite with them open. If not, check that the stud that the condensor and coil lead connect to is assembled correctly on the points. They should both be between in insulator and spring as indicated on the photo.[frame][/frame]

I didn't think to check the points like that! When I put them in, I put the coil lead connector on the bottom of the spring and the condenser lead on top of the spring, would that cause problems at all?

I think tonight I'll head out and put all the original parts back in, then repeat the process, checking with the multimeter as I go along...

[alexmcguffie]

Putting the wires as you have done is fine.

Good luck for tonight

[bmcecosse]

As long as everything is insulated from the base....doesn't matter if top or bottom.. DO check the little flexible 'low volts' wire in the dizzy..... Quick check for 'fuel' = pour an egg cup full down the carb - does it run?

[Casiofi]

So a quick update - still nothing.

I tried sticking some fuel directly down the carb and turning it over, no joy. So I think I can rule out fuel being a problem.
My new coil came but that didn't make any difference - bmcecosse, you get one free jibe!
The low volts wire in the dizzy didn't look too healthy, though I have also tried it with the one that came with my points, no difference.
I tried wiring the coil directly with new wires and new spade connectors, one from the coil to the dizzy and one from the coil to the RHS of the fusebox ( the side that only works when the ignition is on) and still nothing. Is that the correct way to wire it up?

I'm thinking there must be something really simple that I'm missing. Unfortunately my multimeter has given up the ghost so I can't really check much more for now. If anyone has any ideas, I'm completely stumped!

[bmcecosse]

You're test wiring is right enough... So -basics - is there some 'sparking ' at the points when you flick them open/closed? You NEED a meter - or at least a test lamp ..... Does the coil get warm ?

[panky]

Just a couple of thoughts. You changed the HT leads but does that include the king lead? Have the points closed up, are the wires to the points definitely under the insulator - that same Viva I had would only run with those two wires a certain way around on the post for some reason

[Casiofi]

Success!!

It turns out the coil was at fault after all!
Used a motor to check that the 12v feed to the coil was supplying current, which it was.
Then checked that the points were operating correctly by cranking it over with the dizzy cap off and the motor over the coil, which they were.
Then tried turning it over with a spark plug connected to the king lead from the coil - no spark. Changed the coil over and got a spark, so reassembled and she fired up first time! Not exactly sure what I was doing wrong before, but all seems well now. Everything is wired back through the original loom rather than the test wiring that I had in place, but with new spade connectors to ensure all the connections are as good as can be. Thanks for all the help everyone!

[panky]

Excellent, glad to have been of absolutely no help what so ever