47 replies to this topic

[bluequinn]

I did some more testing and have more information

Firstly, I have a big fat spark at the king lead from the coil, and sparking at the points, which are opening and closing as they should. 

But I have zero spark at the plugs. I tried another known good spark plug and got no spark there either. 

 

I'm guessing this means a failed condensor, yes?

 

My thinking is to go straight for an electronic ignition conversion and do away with the old setup.

 

My second discovery was that i am sometimes able to crank the starter motor by simply waggling the wires that lead to it behind the grille. I must have a short in that section of the loom. Not ideal. However that's a secondary problem.

[gazza82]

If you get a spark from the king lead then the problem is probably the distributor cap or rotor arm.

 

The small carbon brush is still there I guess? Transfers the spark from the king lead via the rotor arm to each plug in turn .. they can, and do, drop out!

[Ethel]

The points look a tad burnt to me, but that's just from a photo & if they've been in there for years that could be why as much as a specific fault. It would suggest the condenser, but if you're getting a good spark out of the king lead, maybe not. The points & condenser are service items, so just changing them would have been routine in this situation - BUT, there's enough dodgy new parts out there so  you should at least hang on to the old ones if you do replace them in your search for a cure.

 

As Gazza says the distributor cap would be the prime suspect from your last post. It's another item that's worth carrying as a spare. You can do some confirmatory diagnosis by fitting each plug & its lead directly to the coil to see if they spark. Not too necessary, but if you're going to order parts online it could save you making an extra order.

 

Just leaving the filler cap off would eliminate a blocked fuel tank breather & a good start with the fuel system is to take the fuel hose off the carb & crank the engine to see if it's pumping fuel. Catch it in a bottle & you can use it to splash a little directly in to the carb's air intake to see if the engine catches on it. As has already been said though - always check the ignition first.

[Steam]

Forget the condensor, electronic module or any fuel issue until you have spark at the plugs. As said above cap or rotor arm. Once you have a good spark at the plugs you can then start to sort it.

[Mr Piggy]

Could also be rotor arm. If you crank it,holding the king lead about 6mm above the brass part of the arm the spark should not jump to it. If it does, the insulation on the arm has failed. If the rotor arm is good the spark will try to go somewhere else, like up your arm! So plastic pliers are recommended.

[68+86auto]

It is not recommended to test electronic ignition systems with the leads disconnected.

[bluequinn]

Hello again,

 

It has been a while. I have a house renovation I have been finishing off, but today I did some more on the Mini.

 

I replaced the spark plugs with new, correctly gapped, NGK BP5ESs (also have some Accuspark AC9C which are a 6 heat range)

I fitted new HT leads, a new distributor cap and rotor arm. (and took very great care to put the leads in the right place.)

I fitted and gapped some new points and a new condensor.

Basically every part of the ignition system apart from the dizzy itself and the coil is now brand new.

 

None of that helped.

 

I took the float chamber lid off and it had fuel in it. I removed the dashpot and blew the carb jet clean with some compressed air. I did the same to the fuel tank breather pipe. 

 

And it still won't start. Not even a cough.

I am running out of things to try.

Edited by bluequinn, 28 April 2025 - 12:49 PM.

[bluequinn]

Still no spark.

 

It's got to be the coil, by now, hasn't it?

[sonscar]

Take off the coil lead from the dissy and wedge a sparkplug in it.Earth the plug to the block.Take off the wires from the negative coil terminal.Use a wire to connect the negative terminal to the engine block with the ignition turned on.Tap the wire on and off the block and the plug should fire.Do you have power to the coil in run AND crank positions.Steve..

[68+86auto]

Switching out all those parts now means you could've introduced more issues.

DO NOT buy any more parts unless they are TESTED to be faulty. You are throwing money and time away. New doesn't equal better.

From your previous reports, you have a voltage drop issue but your distributor is working. Fix the voltage drop and your issue may be fixed.


Most new distributors are garbage, don't buy one.

Edited by 68+86auto, 29 April 2025 - 04:32 AM.

[gazza82]

When you swapped out the contacts and condenser did you make sure the small plastic top-hat washers are in the right places?

Also check the small lead coming off the same contacts connectors is still in one piece. It's very fine and over time the wires break .. one tug too many and ... 😞

[bluequinn]

When you swapped out the contacts and condenser did you make sure the small plastic top-hat washers are in the right places?

Also check the small lead coming off the same contacts connectors is still in one piece. It's very fine and over time the wires break .. one tug too many and ...

 

This has thrown me. I have no idea.

I didn't notice that there *were* any plastic top hat washers. Can you provide an illustration so I can check?

 

The small lead did indeed look frail, but I think it is still intact.

[68+86auto]

When you swapped out the contacts and condenser did you make sure the small plastic top-hat washers are in the right places?

Also check the small lead coming off the same contacts connectors is still in one piece. It's very fine and over time the wires break .. one tug too many and ...

 
This has thrown me. I have no idea.
I didn't notice that there *were* any plastic top hat washers. Can you provide an illustration so I can check?
 
The small lead did indeed look frail, but I think it is still intact.

Your model of distributor doesn't have them.

[bluequinn]

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.

[bluequinn]

Just back from a good whizz through the countryside. It's running like a champ again! Phew!