MG
The Classic Marque

I think the idea is to switch off the engine first. Then do the spark test.

Due to the uncertainty of this problem I just know that if I run the engine it will be fine!!
Don’t want to drive the car as 1: it will be fine or 2: not start again like on Wednesday then need to call out breakdown again.
Fairly certain that when the issue arises then the spark plugs are black which wou...

Didnt realise that David. Not that I have ignition electronics, but perhaps not good to suggest to Les then.
Removing a plug lead was standard diagnostic procedure for tracing a misfire. The lazy cylinder, not contributing to the running so no change when disconnected identified the area to look next.

Come to think of it I once saw a young mechanic pin point a misfiring cylinder on a ...

I've been advised to never remove an HT lead when the engine is running as it can lead to damage to the ignition electronics.

When it dies, does the engine keep struggling along or does it stop entirely? If the former, then have you tried pulling one lead off in turn whilst it is running? If you can pull one lead off and there is little or no change in how it runs then clearly that cylinder isnt 'assisting' and is where the problem lies.

But DO USE INSULATED PLIERS when pulling the leads off! In my younger days...

That doesn't sound too good-
Best Wishes

willy

Lonnie--just watched your video.
Starting from the front, the gearbox movement looks about normal
The universal joints appear ok
The diff movement is no good, I suspect this is where the bulk of your noise is coming from--- removing the tailshaft and checking the pinion nut would be the first step, if that is loose and tightening it up rectifies the in/out movement you 'might' get away...

Les---If you have a spare rotor button I'd give that a try first-------- but failing that I'm starting to think ign. module. I doubt it's fuel if your plugs are dark, unless it's actually flooding up on you. You mentioned earlier that your car has an alternator-? if so then it's running negative earth, so it would be a negative earth electronic ignition. This raises the question of coil polarit...

Lonnie - you've received good advice, and you're on the way to correcting everything. May I add: what a great (brief) video to clarify your issues. Way above my skillset, but could you advise what the camera setup is? Thank you. John.

Les.

Your 'debris in the fuel line' comment made me wonder whether fuel hose in the line could be collapsing in the way hydraulic hoses are known to.

Could it be disintegrating in a way that creates a sort of flap that is drawn out to block the line when fuel's flowing or by 'jiggling' as the car's in motion but relaxes when there's no flow and the car's stationary?


C

So, possible causes that I can think of:-

•Faulty electronic ignition for what ever reason ( will do Alan’s test) - apparently if the alternator is over charging then that can damage the electronic ignition. I can test for that.
•Faulty fuel pump
•Sticking float chamber needle valve in one or both carbs
•Blocked breather on fuel filler cap -don’t think it’s thi...