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On 2 Sep 2006 at 18:06, Constantino Tobio wrote: > So, my 73 Fasty won't start. From the looks of it, I'm not getting > spark- holding the coil wire near a ground shows no spark whatsoever, > and I smell fuel in my exhaust, so I'm pretty confident that the fuel > part of the operation is good. > > I get voltage to the coil- on both sides, but I also get voltage on > both sides when the points are open. I tested out the points and > they're not shorting. I swapped in a new condenser, but this was just > throwing parts at the issue- both condensers are Bosch, as are the > points. > > Disconnecting terminals 1 and 15 of the coil, and putting a multimeter > across both lugs, gives me a resistance of zero ohms, and running the > meter for continuity test shows it's indeed continuous across the two > lugs. Resistance from each lug to the coil wire connector is around 8k > ohms. I'm reading that resistance across 1 and 15 should be more like > 20,000 ohms. Some time ago, I worked up a mathcad program to show the spark energy as a function of RPM and coil style for the stock VW/Bosch coil and the German Bosch Blue coil. I measured several stock coils to get an average and came up with a primary resistance of 3 Ohms and a secondary resistance of 9.3 kOhms for the stock VW/Bosch coil, so your numbers don't sound that bad. The zero you measure for the primary makes me wonder whether your Ohmmeter just isn't on a low enough scale (or doesn't have such a scale. For comparison, you need to measure something else that has a known resistance in that same range. Measuring between the 2 posts on the generator (with the DF wires off) should give you 3.5-4 Ohms, IIRC. > So, indeed it appears that my coil would be shorted across the two > windings somehow. > > Is this diagnosis sound? The coil appears to be an OE black coil, best > as I can tell its the one it came with. Still, given what you've told us. A bad coil, with shorted turns somewhere sounds like the only remaining possibility. Yes, I have several good ones here. If yours is actually a genuine original, that would be the first one I've heard of that went bad. OG coils will have the VW & Bosch part numbers stamped on the bottom. > If I do indeed have a sound diagnosis, Jim- I may be interested in one > of your OE black coils. Yes, I've still got some. I've never had a bad one. Just saw your second post. It's quite possible to have just a few turns of one of the windings short out to one another. This will still ruin the coil even though the change in measured resistance is insignificant. -- ******************************* Jim Adney, jadney@vwtype3.org Madison, Wisconsin, USA ******************************* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ List info at http://www.vwtype3.org/list | mailto:gregm@vwtype3.org ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~