Plug fouling

[Wildwoodflower]

Hello all,
Infuriating fault with starting that felt exactly like a spark problem ... all running okay, then missing and lack of power followed by failure to restart.
Checked coil, LT signal, points and rotor arm
Found that the spring that holds the carbon rod in the distributor cap was corroded and broken.
Replaced that, car started normally.
Next day it won't start at all.
All plugs look like this.
Was worried it was piston ring leaking ... but can't be that suddenly on all four cylinders. Also note that electrodes aren't wet.
Must be mixture too rich no?
Your thoughts very welcome. It's the Cleon engine, final year of production.

 

[Wildwoodflower]

With a plug out I cannot see a spark. However, it is very sunny and I can't operate the key and look closely as I'm not a giraffe.
I replaced the LT lead to the distributor yesterday as the old one looked crispy. Coil, points and plugs are for months old.

 

[Andy McGhee]

Have you got a spark at the points?

 

[André4Renaults]

Fit a new spark plug and then see if there's a spark. Now do the same to all the leads and confirm the new spark plug produces a spark when connected to all four leads. If so, your leads are good and your plugs will need cleaning or changing. As to the colour of the old plugs, it looks like the mixture's too rich.

 

[Wildwoodflower]

I can't see. There's nobody to crank the engine.
What I can say is that the fault is intermittent.
After changing the carbon rod spring it started every time yesterday. This morning nothing at all.

 

[Andy McGhee]

You can check for a spark at the points by yourself - you don't need to turn the engine over.
- Remove the distributor cap and turn the ignition key so that the ignition light comes on. If you then separate the points with a small screwdriver, you should see and hear a spark. It should just take a couple of minutes - don't forget to turn off the ignition, though.
- If there's a spark, you know the problem's between the distributor and the plugs. If you've changed any of the leads, it's worth checking that they're pushed fully home.
- Make sure that the rotor arm's pushed fully home, too - they sometimes get stuck.
- If you've had to replace the spring underneath the carbon brush, it'd probably be worth replacing the distributor cap (there are different types; if you could post a photo of your distributor, we'd be able to give you the part number).
There's a good guide to plug condition here:

Contrôle de l'aspect des bougies d'allumage

Contrôle de l'aspect des bougies d'allumage

www.la4ldesylvie.fr

 

[Wildwoodflower]

Thanks. Yes, it is sparking at the points.
I think I may have worked out what is happening..
It's this bugger.
Here it is with the replacement spring made from the innards of a pen.
Next to it is the remains of the old spring..
Can it be that the new spring isnt making a solid contact with the metal cap at the top of its cup?

 

[Wildwoodflower]

This fellow here.

 

[Wildwoodflower]

And there she goes!
Trimmed half a turn off the spring and reseated it. Started instantly.
Who'd have thought it?
The ignition is entirely reliant on this tiny, corrosion prone and fragile spring.

Now to adjust the carb to get it running a little leaner.
Thanks to everyone for the help.