<VV> No spark

[FrankCB@aol.com]

        While I certainly agree with the use of a voltmeter/DMM/test light to 
trace out the ignition circuit as Jim so aptly describe, you can take a short
cut by connecting a jumper wire from the positive battery terminal directly to 
the positive terminal on the ignition coil (this is NOT the one with the 
black wire going to the distributor).  Now try to start the engine.  If it starts 
and runs, you know the problem lies in your wiring UPSTREAM of the coil.  If 
it still refuses to start, your problem lies either with the coil or the wire 
going to the distributor or with the points/condensor inside the distributor.
       Needless to say, you can't continue running the engine on this jumper 
cable since you have no way of shutting off the engine from the driver's seat 
and the full 12+ volts applied continuously to the ignition points will 
shorten their life considerably.  But as a short test, it should help to localize 
your problem.
       The above, of course, assumes that lack of spark is the reason for 
your inability  to start the engine.
       Reminds me of the time I rebuilt both carbs on our Corvair and, a few 
days later, noticed that the engine cut out only in sharp right turns.  As 
soon as the car straightened out the engine resumed operating.  Of course I 
jumped to the "obvious" conclusion that the problem was due to the carb rebuilding 
I had just done, but I delayed the task of rebuilding them again.  I delayed 
until I lucked out one morning when the car refused to start at all.  Lucked 
out because it's MUCH easier to find and fix a problem that is permanent instead 
of intermittent.  So I quickly discovered that the wire from the coil to the 
distributor had partly missing insulation which moved to the left on sharp 
right turns and grounded out the ignition thereby eliminating the action of the 
ignition points until the car returned to straightahead driving.  (This was a 
1966 A/C car so the coil was located such that the wire could easily ground out 
if its insulation failed.)
       So if the points do not serve to interrupt the flow of electric 
current through the coil at the proper time, the ignition spark will either not be 
created or will be made at the wrong time.
       Good luck and let us know what you find.
       Frank "occasionally lacking spark" Burkhard

In a message dated 10/3/04 9:18:58 PM Eastern Daylight Time, 
simpsonj@bellatlantic.net writes:

> Sounds as if you need a voltmeter or at least a good continuity checker of 
> some kind.
> 
> Check to see if there is voltage at the points with the points open and the 
> ignition on.  If there is, then make sure the points are clean.  If NOT, 
> then start tracing back to see where voltage first appears -- at the 
> negative end of the coil, the positive end of the coil, etc.  Check all 
> those crimped connections -- they do corrode or loosen.
> 
> One commonly overlooked component is the black wire the runs from the coil 
> to the points.  Over time,  between the flexing caused by the vacuum 
> advance operation and the hardening of the insulation, this wire frequently 
> breaks internally at the point where it goes through the side of the 
> distributor.
> 
> Jim Simpson, Group Corvair