Hey Mick, thanks for that in depth yet simple explanation. Hopefully it will help me get to the bottom of this problem.
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| Author: | TimB [ Mon Oct 06, 2008 12:39 pm ] |
| Post subject: | No spark? |
Quite a few weeks ago my mini wouldn't start and has been that way since. After testing a few things suggested in the Haynes manual I replaced the coil and condensor but still no luck, the problem of no spark seems to be somewhere between the coil and the distributor. Any suggestions? |
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| Author: | Hanra [ Mon Oct 06, 2008 12:47 pm ] |
| Post subject: | |
Do you have 12v at the + of the coil with the IGN on? |
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| Author: | Mick [ Mon Oct 06, 2008 1:10 pm ] |
| Post subject: | |
An easy check is to pull the high voltage coil lead out of the distibutor, hold close to the block and crank the engine over. If there is 12 volts at the coil, and you have spark from the lead (when tested as above), then it will be the distributor cap/rotor button/leads that need replacing. It may be just one of those items, but if one is gone then the rest probably won't be far off anyway. It's good sense to clear the slate of old leads and caps. If there is twelve volts at the coil, the coil is new, and there is no spark..then you need to look at your points and condensor capacitor inside the distributor. Service these in accordance with your book. |
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| Author: | simon k [ Mon Oct 06, 2008 7:41 pm ] |
| Post subject: | |
d'oh - I was in Glenrowan few weeks ago looking for something to do - I could have come over! |
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| Author: | TimB [ Mon Oct 06, 2008 8:02 pm ] |
| Post subject: | |
Well Simon, if you're ever down this way again please do drop in. I don't have a volt meter, only one of those lamp type thingys. Is it possible that the low tension wire and condensor wire at the points can be short circuiting? Can someone explain exactly how these should connect. Also the wire from the coil isn't original, does this need to be of a certain spec? |
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| Author: | Mick [ Mon Oct 06, 2008 8:12 pm ] |
| Post subject: | |
The condensor is meant to connect to the wire from the coil. There are two wires going to you coil. One is twelve volts +ve (the lamp tester you have should turn on here when the ignition is on), and a negative wire going to your distributor. The negative wire is what switches the coil on and off, inside the dizzy is a set of points, these are quite simply nothing more than a switch which turns on and off the coil once every 180 degrees of the engine. You will notice if you turn the engine over that they open and close. If you put your lamp tester on the negativer contact of the coil, you will see it turn on and off as you open and close the points. The condensor is a capacitor. A very sturdily constructed capacitor. It's role is to soak up the high voltage spikes that jump across switch contacts when they are opened suddenly. It will protect the point contacts from being eroded away from all the sparking that occurs when running. If the condensor fails, you will see it short to ground. This will mean that the points will not switch the coil on and off anymore (as they are short circuited) and the engine will stop with no spark. If it goes open circuit (wire breaks or something similar) then the arcing across the points will erode the silver away in a couple of kilometers of driving. Also stopping the spark from occurring. |
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| Author: | TimB [ Mon Oct 06, 2008 9:08 pm ] |
| Post subject: | |
Hey Mick, thanks for that in depth yet simple explanation. Hopefully it will help me get to the bottom of this problem.
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| Author: | BALLISTIC [ Mon Oct 06, 2008 11:14 pm ] |
| Post subject: | |
After you have checked the wires attaching to the coil, Check that you have fitted the points correctly at the post with the nut.....easier with a picture or diagram ....will try and post one tommorrow unless some one beats me to it, check for spark from the coil wire ( as mick mentioned) if that is ok then check these things......  do you have any gap at the points when the rotor turns?
(ignition on) Is there any spark when the points gap opens?
(inside the cap) Is the little carbon brush still in the top of the cap?
When you push on it does it move in and spring back out?
Hope these help Cheers Scott |
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| Author: | 74snail [ Mon Oct 06, 2008 11:14 pm ] |
| Post subject: | no spark! |
also check the voltage regulator and your fuses |
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| Author: | TimB [ Fri Oct 10, 2008 8:25 pm ] |
| Post subject: | |
Checked everything again and power is getting through to the low tension wire at the points connection but the points aren't sparking. I disconnected the condensor mounting and tested the moving part of the points with the points open and got no reading, Haynes manual says it must be the coil. I'm thinking it's got to be the points or the connection of the 2 wires shorting. Am I correct that the 2 wires (-ve from coil & condensor) sit together on the nylon bush that holds them against the spring of the points but insulates them from the stem of the points? Hope that makes sense. How do I check the volt regulator as 74 snail suggests? |
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| Author: | simon k [ Sat Oct 11, 2008 12:03 am ] |
| Post subject: | |
too hard Tim... if it's not going by Friday next week, drop me a PM with a phone number and I'll try to stop by on the way home from Melbourne on Sunday |
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| Author: | TimB [ Sat Oct 18, 2008 9:37 pm ] |
| Post subject: | |
Turns out it was the points. Of course the only thing I hadn't replaced. Thanks for the suggestions. Simon I only just read your post I will pm you. |
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