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Basic Ignition wiring question


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nu2this
New User

Nov 13, 2006, 5:13 PM

Post #1 of 7 (5212 views)
Basic Ignition wiring question Sign In

Hi,
Can someone explain how the current flows to the points when you turn the key to the on position? Does it flow to the coil first then to the points?I have an old 1969 VW bug that wont start. With the key on and the distributer cap off, when I turn the motor over I do not see the points sparking when they open.

Any help would be appreciated.


steve01832
Veteran
steve01832 profile image

Nov 13, 2006, 6:42 PM

Post #2 of 7 (5206 views)
Re: Basic Ignition wiring question Sign In

I don't have a wiring diagram for something that old. Typically, the coil is fed 12 volts. The points make and break the ground side of the coil. If the coil primary has 12 volts then you should check the negative side of the coil with a testlight connected to ground. The light should flash as you crank the engine over. If it does, replace the coil. If it stays on solid, replace the points. You can set the gap of the points with a matchbook if you don't have the specs. Usually they are around .016-.025 inch but man it's been a long time since I've worked on that stuff. Good luck and let us know what happens.

Steve


Tom Greenleaf
Ultimate Carjunky / Moderator
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Nov 13, 2006, 8:03 PM

Post #3 of 7 (5206 views)
Re: Basic Ignition wiring question Sign In

In general the start position gives full available voltage to the coil and run position is filtered thru a balast resistor to lower voltage to preserve points. When points are open a test light will light at coil and at the points where a wire goes to a condensor which in a nano second can store up the power to give it good spark.

If seeing no spark at the points test for voltage with open (high on cam) and maybe the condensor has shorted and just eats all the available current.

A dwell meter can and is very helpful for setting points to exact spec but a feeler gauge can work if you are real good. At its age it may need a new or rebuilt distributor because of bearings and a dwell meter is great at verifying that or just get a feeler gauge in the points and push-pull on the rotor and see how much freeplay you have. Good luck and hit back if you need more help I'll do my best, T



Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Nov 13, 2006, 8:10 PM

Post #4 of 7 (5205 views)
Re: Basic Ignition wiring question Sign In

Hi Steve! We both hit that at the same time but I didn't finish because a long phone call came in and I can't type and talk to someone at the same time. It's like the walk and chew gum thing Smile T



nu2this
New User

Nov 14, 2006, 8:18 AM

Post #5 of 7 (5200 views)
Re: Basic Ignition wiring question Sign In

Hi,

Thanks to both. The car had been giving me some trouble in as much as it would start and then for no reason quit. Befor it would do that though the tach go to zero and all the gauges would stop working then the engine would die. Icould reach up under the dash, jiggle some wires and presto---------it would run. So it thought I have some wireing problems. The car is a Kit Kar built from a Vdub and is fiberglass.

I have been told that these cars are notorious for beeing poorlly grounded. Perhaps thats the problem. Whatever, I want to hotwire it to move it out of my shed. I ran a wire from the Neg side of the coil to the Positive batterypost hit the starter and it fired right up. I let it run for a minute or two and then it shut it off. I connected a test light to the (-) Side of the coil, grounded the light and got no light. If I probe the case of the coil the TL glows. Might I Have a bad coil or am I doing this test incorrectly?

Thanks for any help,-------------Ken


steve01832
Veteran
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Nov 15, 2006, 3:52 AM

Post #6 of 7 (5194 views)
Re: Basic Ignition wiring question Sign In

The test light should flash when the engine is cranking. If the light is off, try bumping the engine with the key. The test light should go on and off. Bumping the engine means to hit the key to crank for a split second so the engine rotates extremely slowly. Also, investigate the wiring under the dash as this could be the root of the whole problem. I would fix this first before going into the ignition system .

Steve


nu2this
New User

Nov 16, 2006, 1:35 PM

Post #7 of 7 (5179 views)
Re: Basic Ignition wiring question Sign In

Thanks you guys,

I was able to get it startedSmile.

I totally agree that the wireing under the dash needs to be addressed. I will do that later. At least I got the car out of the shed and got it cleaned.-------------Thanks again.

Ken






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