73 240 No spark

[Shawninvancouver]

OK, good idea.  i will test those two wires next... i am sure i am not getting spark as the green/white needs to be going to the ballast..

just need to figure out which black and black/whites i need to to use the ballast and to the coil.. but the posted video explains that clearly..

[Zed Head]

On 4/28/2024 at 10:32 AM, Shawninvancouver said:

I do get power to the coil.  Both pos and neg have power.  When trying to start the car I have power leaving the front of the coil.  

What does "leaving" mean?

If you have voltage at the coil there's no reason to focus too much on the wiring if you're only trying to start the engine.  

Give a better description of what you're actually seeing.  How do you know you're not getting spark?

[Shawninvancouver]

hey Zed,

I have tested for voltage coming out of the coil where it goes to dizzzy.. power is coming out of it..  it also has power with the key on position... but no spark.

not getting spark as i have spark plug test light hooked to engine to show when spark.. no spark.. also have tried 3 dizzys/// they all were cleaned and looked good.. i have read a few things of green white wire and the tach,, and if tach aint hooked up the car wont get spark.. true>???

[Zed Head]

30 minutes ago, Shawninvancouver said:

out of the coil where it goes to dizzzy.. power is coming out of it..  it also has power with the key on position... but no spark.

If "power" is coming out of the center wire of the coil - that is "spark".  You're still not describing where, exactly, you are looking when you say "no spark".  

When testing just the coil and points you should remove the center wire from the top of the distributor cap, leave it connected to the coil, and do your spark test.  Place the end of the wire close to a grounding point, like the intake manifold, close but with a small gap for the spark to jump.  Then do whatever you're doing to look for spark, spinning the engine or opening and closing the points by hand.

The spark from the coil passes to the center of the distributor cap and is picked up by each spark plug wire electrode as the rotor turns inside the cap.

 

Edited April 29, 2024 by Zed Head

[Yarb]

Have you read the electrical section in the FSM? There aren’t simple answers for a car that hasn’t run in a very long time. You have to get educated with the system and follow the trouble shooting listed in the FSM. It can be numerous issues contributing to this. According to the experience level makes a huge difference. A test light isn’t the the answer alone. Grab an DVM and start taking ohm and voltage measurements per the FSM. Make notes as you go to eliminate possible defects etc. Step by Step it’s a very simple ignition system.

[Shawninvancouver]

ok.  i am no electrical genius,  when i tested the coil i put a volt meter on end of coil - center of it where wire goes to dizzy and tested volts.. i assumed it should have voltage, which it did.. i am just looking for some clarification if the car will start/get spark, if the green/white tach wire is not connected to the ballast resistor.. ??  what are the effects when tach wire not connected? i have read the car wont start.. is that true??

zed, when i say no spark i mean at the plugs in the engine, have tested them with a spark plug tester and held plug near metal when trying and have never seen spark,,,  could it be 3 bad dizzys or a green/white wire not connected???

[Yarb]

Are you turning the car over when you’re testing for spark?

[Shawninvancouver]

Of course Yarb. I’m a hack but not that dumb.  I do have power.  Starter motor is cranking. Just no bloody spark.  Any idea on green white tach wire?  Do those spark plug testers work. ??

Edited April 29, 2024 by Shawninvancouver

[240dkw]

You cannot use a meter to measure the high voltage coming out of the centre post on a coil, read what Yarb/ Zedhead are saying as to how to test it, they are trying to help you. Maybe study the pages it might help you.

Edited April 30, 2024 by 240dkw

[Zed Head]

5 hours ago, Zed Head said:

remove the center wire from the top of the distributor cap, leave it connected to the coil, and do your spark test. 

Place the end of the wire close to a grounding point, like the intake manifold, close but with a small gap for the spark to jump. 

Then do whatever you're doing to look for spark, spinning the engine or opening and closing the points by hand.

Pull the wire from the distributor, set it close to a ground point, have somebody turn the ley to Start while you watch the gap.  You should see a spark.  A meter is the wrong tool for a spark test.

Your distributor connection is obviously different than in this Youtube short. top of the cap instead of underneath, but you can figure it out.  We all just need to hear from you that you've done this and nothing happened or somethng happened.  We need something concrete to understand about what you're working on.  It is a very common and well-known spark test procedure.

 

[Patcon]

Some cars have proven to be sensitive to the tach being missing but not necessarily all of them. It's a little bit of a mystery.

You also need to understand how the guys on the forum help. We don't like to assume or overlook the obvious. So you need to be very descriptive of your procedures. We will get a solution faster that way. 🙂

[Captain Obvious]

The 240s run the ignition signal THRU the tach, so no... The car (in stock wired configuration) will not spark unless the tach is connected.

If you want to hotwire the system and bypass the tach and much of the original wiring, try this...

Take the wire off the front side of the ballast resistor.
Run a jumper wire from that front end of the ballast  directly to that "+" battery terminal.
Crank the car and see if you get a spark. 

If you get a spark, your points are working correctly and the problem is elsewhere.

Here's a pic of what I'm talking about: