I'm in a bit of a pickle, and I need some advice. My S is struggling to start. It will strike, and make a quick burst to perhaps 2000 RPM, before it collapses and stops. Today, it will do so perhaps 3 times before it stalls completely.


A video of the car struggling to start is in the link:
https://photos.app.goo.gl/yNrUcH2mjiucm5Wj7

My engine bay layout is in the image, but is 1275 with twin 1.5 SUs:
https://photos.app.goo.gl/8NU8hfpcrr3cjhJu9


To this date I have exchanged every part of
- the ignition (cap, rotor, leads, points module, spark plugs and coil) and monitored the supply for consistent 12 volts through start (yes).
- I have looked for induction leaks, and found none, including by blocking off the PCV and Booster.
- Regardles I pulled the carbs and manifold down, and rebuilt, including manifold takeoffs. The jets are clear, and bowls have the right levels of fuel, and the gaskets are all new.
- The dizzy curve is locked, and there is an accuspark blackbox. I have removed the box and connected the dizzy straight to the coil. No change. I even took the opportunity to try out the new stealth mk3, to see if it was the old stealth mk1 that was the problem.
- I've drained and replaced the fuel, clearing the lines to ensure a fresh batch.
- Compression is great, and it seems to fire on all four cylinders when it does kick.


I'm pretty happy ticking along with it, but I'm out of ideas to chase. I'd appreciate ideas, and will happily retest if I need to.

cheers

Mick

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Dashpot oil correct?? Car will run without oil but will be a B^&%$ to start....

Cheers, Ian

Thank you. I've topped them up yes. Proper SU brand and all this time too ( first time ever)

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Some ideas.
Starting and immediately revving to 2000 would suggest severe overfueling or flooding before the carbs runout of useable fuel.
Air leaks also cause this phenomonen.
I have had severly blocked air filters cause overfueling before stalling.
However I must say that it sounds like ignition on you video. Would it be possible to switch in a completely standard points setup to prove / disprove.. Do not assume new parts are not faulty either!!!
Also a rather last ditch trick I have used is to put 10 or so mls of fuel in each plug hole then try firing. It may eliminate the igntion.
Bset of luck.

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Cheers Dave.

Some more things you can double check:
Base timing it set correctly
Spark plug gaps set - and are the spark plugs fouled?
Are the leads on in the right order?
What’s the resistance from the inside the distributor cap terminal to the spark plugs end of the lead?
Which ohm coil did you fit?

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It seems like an ignition fault to me (I hear a backfire?) although since the carbs have been apart there could now be a combination of faults.

You could try disconnect the tacho, faulty ones can cause issues.

Since it's a 29d, the cap and rotor will be used unless you've got NOS. Are they definitely good?

The ignition system should always be proven to be working correctly before the fuel system is touched. Carbs rarely fail suddenly.

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1986 Mayfair (998 auto), 1974 S, 1974 Van, 1972 PMG Van

Too many minis

Yeah I agree. I'd definitely be going through the ignition system Mick.

Just watch that highly erratic pulse of the strobe light and match it to the running (or not) of the engine.

Do you have another known good dizzy you could throw in to eliminate that as the culprit? Any one will do for the purpose of the exercise.

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Cheers,
Rod.
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'63 Morris 850 (Old Secondhand CAR)

Sorry, I've been away the last couple of weeks, but am back again. Yes I'll chase out the ignition system again, but I've exchanged everything so far (excepth the body of the dizzy). It might be time to drop in a 25d I have spare.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

I have just listened to it again and I wonder if it is the firing order or the timing that is out or it is only firing on 2 or 3 cylinders.

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Cheers Dave.

Fine crack in the distributor cap caught me out once.

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1970 Mk2 Cooper S under restoration

The 29D dizzy caps are rare parts these days. I replaced the cap with a "good" used one I had, and then with another two old black LUCAS caps I had floating around, but the problem remained. Same with the rotor button. Good news was I replaced the dizzy with a 25D and the problem disapeared, but I'm going to platy with the module (and also check the advance mechanism beneath) as I think that might be the next stop.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Does the 25d have points or is it on the same electronic system?

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Cheers Dave.

Electronic points. I haven't gotten to the dizzy yet however, work keeps me pretty busy, but its on my mind a lot.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

What's the condition of the flexible wire between the advance plate and body?

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1986 Mayfair (998 auto), 1974 S, 1974 Van, 1972 PMG Van

Too many minis

Ah yes, I did replace that wire, +ve and the -ve as well. It may have been those connections.

When I get to the dizzy I'll pull her down anyway, and replace with the new wires included. Maybe the wire strands were fractured.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.