Condenser failure

[bluez]

Thanks for the suggestions, got sidetracked today, will spend some quality time tomorrow, and provide an update tomorrow.
I did previously check polarity and other wiring connections all appear good, also tried disconnecting the condenser and had no spark. Will see what tomorrow brings.

[bluez]

Okay, did some testing today. Still getting initial spark when key is first turned to start, then nothing. I did notice the new coil appears no longer flat on the bottom, looks to be swollen. With key in run position and points open I see 12v at coil, resistor, and points. Thinking maybe the new coil is bad?

[cgsheen1]

The coil only gets battery voltage at when the key is turned to the ON position, correct? No voltage otherwise? (The B/W wire(s) on a Datsun should have battery voltage while IGN ON - otherwise zero voltage)

This is a fairly simple circuit (considering they looped back the battery voltage feed for the coil from the ballast to the Tach and then to the coil). A couple of things: It's a coil. So when it has battery voltage on the "+" pole, it also has battery voltage on the "-" pole. Which if you connect that (the "-" pole) to one side of the points, it also has battery voltage there.

The coil is "fired" by very very very briefly connecting that pole to ground. Check your ground circuit from the distributor to the points, through the points, and through the wire to the coil (removed from the coil for the check). Also check that the points actually break the connection to ground. My final thought is your point gap which at .50mm is at the upper end of the ".40mm - .50mm" spec. - You might try reducing that to mid-range and see if that makes a difference.

I vaguely remember back in the mid-70's that I had to buy a dwell meter and learn how to use it for my stinking Ford 351 Windsor engine which I had to tune every three months. Just one reason that once they invented EFI I never went back to a carbed and/or points vehicle...

Wait. You get one spark when the ignition is turned to ON? Doesn't that mean the coil "-" is getting a ground right at that moment? Where is it getting the ground? Are the points closed at that time?

Perhaps you should check the coil sparking by manually creating the spark condition.

Edited October 21 by cgsheen1

[bluez]

Yes coil, resistor, points only have voltage when key is on. I rechecked points, gap .48, points are fine. Have 12v when points are open, 0v when closed. Noticed when key is on for short time 2-3 minutes the coil gets warm and resistor get hot quickly. Seems odd that a plug initially gets spark, then nothing. Will order a coil.

[Zed Head]

11 minutes ago, bluez said:

when key is on for short time 2-3 minutes the coil gets warm and resistor get hot quickly.

That's normal if the points are closed.

There is a resistance test for the coil.  You might try that first.

The single spark actually makes sense if the coil has a circuit to ground continuously.  When you turn the key on the coil is energized.  When you turn the key off it is de-energized and a spark results.  It is a clue that you have a short to ground somewhere on the wires after the negative post of the coil, or the points are not opening.  Check all of the wires after the negative post, and the points, and the condenser.  Make sure that they are connected correctly.

A shorted condenser would do it too.  You can test the condenser with a meter also.  It should have OL, Open Line, infinite resistance on the meter reading.  Even though it is connected to ground it does not pass any current.  Remember, new does not mean good.

Edited October 23 by Zed Head
+ o

[bluez]

Ok thanks, short to ground makes sense. The points are opening. Will check wires more closely. The condenser wire has been disconnected for now. The new coil being deformed, raises some suspicion.

[bluez]

Spent a few hrs the last few days, tracing/testing wires. So far nothing found. Am now seeing some weak spark on the plug when cranking.  Today, I tried a new coil, no change. Decided to reconnect the condenser, to my surprise the motor fired right up several times, then nothing. Then tried again with the condenser disconnected, got nothing.  Back to tracing wires.

[Zed Head]

Try bypassing the resistor and see what happens.  Jump it end to end or just move the one on the end of the resistor to the Start post.  It is bypassed on the Start circuit so you might be right about the bad coil.  Maybe the coil is weak and needs full current to create a spark.

It will be another clue if it works.  Could be a bad coil or it could be a bad ballast resistor.

Or put the old ballast back on.

[bluez]

More quality time spent, swapped coils, resistors, tried no resistor/condenser. Still nothing, not even a pop. Everything under hood seems fine. Tomorrow will either try going back to PEI, or look at tach wiring.

[Yarb]

IMHO time to pull out the multimeter

[Zed Head]

Hot wire it.  Run a jumper from the battery positive to the coil positive post.  It it starts and rnus then you'll know that the distributor and coil and points are fine, and you can focus on the wiring and tach.

Not sure I saw rotor and cap discussed.  It might be that spark is being created but it's just not making it to the spark plugs.

Hitting Submit even though Yarb has replied.  Let's see....

[bluez]

Have already had test light and meter out checking continuity, voltage and resistance. Not seeing anything amiss, am missing something. 
Great idea hot wire, hadn’t thought of that.