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Engine Died. Some Internet Diagnosis Please?


Best Answer bluequinn , 07 May 2025 - 12:17 PM

Update. My Mini is running!
 
A friend who is very good at fixing mechanical things came round today to help me fix the Mini. 
To recap, since it died I have replaced the points, condensor, rotor arm, dizzy cap, spark plugs and HT leads. Plus the vacuum advance hose, because it's rubber bushings were looking quite tired. (Also a new air filter, oil filter and oil change, prior to this)
 
We started by checking voltage to the coil. 13v present and correct. Then he directly attached a plug to the coil (as per sonscar's suggestion above). It had no spark at the coil, but then after some tinkering we got a good fat spark. To be honest I have no idea what that tinkering was. Anyway, with the cap off and a nice spark at the points, the Dizzy cap went back on and we had good sparks at all the plugs. But it still wouldn't start. Plugs out, lots of compression, so that was alright.
 
My friend thought the plug leads were in the wrong places, and had got them in what appeared to be the right order. We looked again at this, and suspected we were 180 degrees out, so we swapped them over. 
That got it running on two cylinders. Then we swapped two around again, and we got all 4 cylinders back again!
 
The engine ran but was running very fast and the revs weren't dropping, so he gave the carb a good clean and check over, adjusted the throttle cable, and got it idling properly.
 
We suspect the coil is breaking down and caused all this (although the old points were looking quite fried). A new coil will be ordered today.
 
And an electronic ignition conversion while I am at it, now that it is running properly again.
(Would you still call it modernising when you would be fitting something to a 1991 car that even my old Vespa had back in 1978?)
 
I am going to give it a proper test drive now, and see if it has any more issues.
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#16 Designer

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Posted 05 April 2025 - 12:58 PM

Hi,

 

Check the connection between the black wire coming out of the dizzy and connecting to the white wire with black tracer(or black wire with white tracer which ever way you see it).

I had similar problem and a bad connection there was the culprit.

 

Paddy



#17 bluequinn

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Posted 05 April 2025 - 05:12 PM

Here’s the inside of the dizzy. Not much access or time to do more than that today.
New points and condenser in 2016. That’s long enough for them to go bad but it hasn’t done that many miles in that time.

How can I test this? Just test for spark or something multimetery? I have never had a vehicle with points before.

If I’ve got to replace them I’d be daft not to change for electronic ignition, right?

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#18 Quinlan minor

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Posted 05 April 2025 - 05:36 PM

That cam pad looks mighty dry. That'll accelerate the heel pad wear, a lot.

Check the points gap. I won't be surprised if it's closed up from the ideal.



#19 timmy850

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Posted 05 April 2025 - 08:54 PM

The rotor contact also looks a bit corroded. You can scuff that up with a wire brush to get shiny metal on the edge and the centre. While you’re there, the contacts inside the cap need to be clean too

There’s lots of small items throughout the ignition system that can add up to misfires or no start when they’re worn or old

#20 Steam

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Posted 06 April 2025 - 06:20 AM

Nothing obviously wrong from your photo, check the points gap/dwell angle and condition of points contact areas. Then pull a spark plug or 2 out and reconnect to lead holding against the block with insulated pliers, see what the colour of thee spark is, should be strong blue white across the plug contacts.

#21 bluequinn

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Posted 08 April 2025 - 06:36 PM

Ok, today I pulled all the plugs and gapped them to 25 thou. Two were too widely gapped. I also cleaned up the rotor arm, and the contacts in the cap, oiled the felt thing, and set the points gap to 15mm. I checked all the coil and dizzy wiring and it all looks Ok, but not perfect. The coil has been changed for a Ducelier one and there are a lot of heat shrunk adaptors for the different connections.

Anyway none of this did any good at all. It will not start.
The starter motor is very strong at least. There was also a good smell of fuel. And brake cleaner sprayed in the air intake didn’t work.

That’s about all the checking I can do without a glamorous assistant to turn the key while I check for spark.

Tomorrow a package of parts arrives, so I can service the carb. Judging by the plugs though the fuelling has been spot on. On Friday my wife returns from a work trip so I can do more checking.

I don’t think I have eliminated anything yet.


Edited by bluequinn, 08 April 2025 - 06:46 PM.


#22 bpirie1000

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Posted 08 April 2025 - 08:05 PM

Check the battery connections. Also the engine earthstrap is certainly worth checking, usually under the engine mount on left hand side of the car. Underthe master cylinder.

I would also say clean up the rotor arm connections.

Edited by bpirie1000, 09 April 2025 - 07:45 AM.


#23 68+86auto

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Posted 08 April 2025 - 10:28 PM

Tomorrow a package of parts arrives, so I can service the carb.

 

Please do not touch the carb until you KNOW what the problem is. If you do something incorrect during the rebuild then it will make more complications in order to get it running. You need to get out a multimeter and measure the voltages everywhere when trying to start it. You don't need an assistant, simply turn the key on and then make a connection between the starter battery terminal and large spade in order to crank. Make sure it's not in gear.



#24 bluequinn

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Posted 09 April 2025 - 08:11 AM

Oh that’s game-changing advice. Thank you!

#25 bluequinn

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Posted 09 April 2025 - 03:37 PM

OK, small update. I have 11 volts across the coil terminals when not cranking. As its a ballasted system it should be lower than that, right?

Would that be a condensor killer?



#26 Steam

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Posted 09 April 2025 - 08:25 PM

Did you test for a spark with the plugs out, should be strong blue / white.

#27 bluequinn

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Posted 09 April 2025 - 08:40 PM

I tried. I don't have the manual dexterity to hold 3 wires at once.

There were sparks, there was a pop, I decided it that discretion was the better part of valour.

 

I shall wait for my wife to return on Friday and she can be on key turning duties.



#28 68+86auto

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Posted 09 April 2025 - 10:38 PM

OK, small update. I have 11 volts across the coil terminals when not cranking. As its a ballasted system it should be lower than that, right?

Would that be a condensor killer?

 

If the points are open, you should see the battery voltage. If the points are closed, you should see lower than that. 11v indicates that your points are probably open and your problem is a bad battery or connection somewhere. See what voltage the battery posts are at with the ignition on.



#29 sonscar

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Posted 10 April 2025 - 07:26 AM

Treat the points as a switch,the cam lobes open the switch turning off the coil and making it spark.On off on off and so on.The rotor is also a switch rotating to send the spark to the correct plug.It is not magic.Steve..

#30 Earwax

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Posted 11 April 2025 - 10:12 PM

the one person alone underbonnet starter procedure ( as mentioned by 68 +86auto) is a winner.  Off track but possibly worth mentioning for the long haul in mini mechanicals

 

google       remote starter button tool - for the ultimate lazy sit on your stool and diagnose helper and relatively cheap. One of the autosparkies on here might be able to recommend some 'heavy duty' types or specs .






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