No spark at coil

Joined
Jan 5, 2017
Messages
3,637
Location
Charlotte, NC & Alexandria, VA
I thought the whole purpose of Pertronix was to replace the igniter , so why use it.



The PerTronix igniter replaces the points and the igniter module in the semi-electronic ignition version of the 40 ignition system. I can't throw parts at the ignition system until I know it's working. An unidentified fault, like the persistent ground I apparently have, won't be solved by installing the PerTronix "igniter".
 
Joined
Jan 5, 2017
Messages
3,637
Location
Charlotte, NC & Alexandria, VA
I thought the whole purpose of Pertronix was to replace fiddly points. I know that's why I would use it.
Yeah, that's the end goal, but if the coil won't spark replacing the points isn't going to help. At this point, I'm chasing a ground fault, somewhere in the harness wiring. As soon as the rain stops...

We couldn't have had any luck Satruday anyway, there was a mystery bug we didn't know about.
 

roadstr6

SILVER Star
Joined
Apr 10, 2013
Messages
5,051
Location
Weddington, NC
Yeah, that's the end goal, but if the coil won't spark replacing the points isn't going to help. At this point, I'm chasing a ground fault, somewhere in the harness wiring. As soon as the rain stops...

We couldn't have had any luck Satruday anyway, there was a mystery bug we didn't know about.
Fred, My comment was more or less directed at @1969FJ and not you. He said the reason to use pertronix was to get away from the igniter. I have always seen it more as a way to get away from fiddling with points...exactly the reason you had planned to do it. I agree that your problem is upstream of the points (or pertronix).
 
Joined
Apr 2, 2008
Messages
10,982
Location
Victoria, BC
The igniter was added to a points system to increase the points useable life. Pertronix is designed to replace it all and get rid of the old technology. I’d loose the igniter and wire the pertronix to the coil. If that unit isn’t designed to run that way, I’d get one that is.

Disclaimer:

My ‘74 never had an igniter.
I ran an MSD 5 and then an MSD 6 still using points (doing the same thing as the igniter)
After a SBC conversion I swapped in Crane Cams Flame Thrower ignition to replace stock SBC points. For years I ran 12(+) to ballast resistor to Coil and then to the Crane Cams unit in the distributor. Now I have a ballast resistor bypass while starting (only).
 

Steamer

SILVER Star
Joined
Jul 20, 2009
Messages
1,762
Location
Miami, FL
Re-reading your first post I see my confusion and maybe for others also. I thought you had a Pertronix “Ignitor” installed in your distributor. What's in the distributor now?
 
Joined
Feb 6, 2002
Messages
15,376
Location
OC, CA
Note that the coil is not part of the engine fuse circuit. The coil is not fused. If you don’t get a big fat spark when manual grounding and ungrounding the coil, then you may have a high resistance connection somewhere. Try a hot wire directly from the battery + to the coil + and try again. If you still have a weak spark, you may have a bad coil. I have only seen one bad coil in my lifetime.
 
Joined
Jan 5, 2017
Messages
3,637
Location
Charlotte, NC & Alexandria, VA
Note that the coil is not part of the engine fuse circuit. The coil is not fused. If you don’t get a big fat spark when manual grounding and ungrounding the coil, then you may have a high resistance connection somewhere. Try a hot wire directly from the battery + to the coil + and try again. If you still have a weak spark, you may have a bad coil. I have only seen one bad coil in my lifetime.
I tried the direct connection, with both coils, which both meg out as good. I'm still stumped. Maybe I'm not holding my mouth right.
 

Engineer8000

CAPE FEAR ELECTRONICS
Joined
Aug 16, 2019
Messages
1,161
Location
SOUTHPORT NC
Website
forum.ih8mud.com
Igniter test, I don't have one of these to test so proceed at your own risk.

Regardless of the internals of the igniter, its job is to ground the coil (-) when the points are closed and open circuit the coil (-) when the points are open. Referring to the EWD, 2SB509 (Q1) Is the top transistor and is a PNP. When the points are closed, the base is at lower potential than the emitter so current flows from emitter to collector. The bottom transistor, TP5022 (Q2) is a NPN transistor. When Q1 turns on, Q2 base is at a higher potential than the emitter so it turns on and current flows from the collector to the emitter. So when the points are closed, Q1 turns on Q2 and the coil (-) is connected to ground. When the points open, Q1 and Q2 turn off, the coil (-) is disconnected from ground and the coil primary field collapses causing a spark on the coil secondary.

I believe the ceramic device mounted under the igniter with the 4 wires connected is a resistor module.

To test the igniter, I would do this:

Disconnect the igniter wires from the coil and ballast resistor so it is electrically isolated.
Connect igniter (+) (yellow wire that normally goes to the ballast resistor) and (-) (assuming metal case?) to your 12v battery.
Connect a 12v light bulb between battery (+) and the black igniter wire that normally goes to the coil (-).

In this condition, it is the same as points open so the light should be off.

Touch the red wire that normally runs to the distributor to battery (-) and see that the light comes on.

Let me know what you find.

1653410170339.png


1653408825825.png


1653410320569.png
 
Last edited:
Joined
Jan 5, 2017
Messages
3,637
Location
Charlotte, NC & Alexandria, VA
Igniter test, I don't have one of these to test so proceed at your own risk.

Regardless of the internals of the igniter, its job is to ground the coil (-) when the points are closed and open circuit the coil (-) when the points are open. Referring to the EWD, 2SB509 (Q1) Is the top transistor and is a PNP. When the points are closed, the base is at lower potential than the emitter so current flows from emitter to collector. The bottom transistor, TP5022 (Q2) is a NPN transistor. When Q1 turns on, Q2 base is at a higher potential than the emitter so it turns on and current flows from the collector to the emitter. So when the points are closed, Q1 turns on Q2 and the coil (-) is connected to ground. When the points open, Q1 and Q2 turn off, the coil (-) is disconnected from ground and the coil primary field collapses causing a spark on the coil secondary.

I believe the ceramic device mounted under the igniter with the 4 wires connected is a resistor module.

To test the igniter, I would do this:

Disconnect the igniter wires from the coil and ballast resistor so it is electrically isolated.
Connect igniter (+) (yellow wire that normally goes to the ballast resistor) and (-) (assuming metal case?) to your 12v battery.
Connect a 12v light bulb between battery (+) and the black igniter wire that normally goes to the coil (-).

In this condition, it is the same as points open so the light should be off.

Touch the red wire that normally runs to the distributor to battery (-) and see that the light comes on.

Let me know what you find.

View attachment 3017146

View attachment 3017127

View attachment 3017147
Here is my test setup:
Position 1 (points open simulation):

20220524_143537.jpg


Position 2 (points closed simulation):

20220524_143547.jpg


test circuit confirmation:

20220524_145342.jpg


So guess the igniter isn't working.
 
Joined
Apr 13, 2011
Messages
1,981
Location
Austin, Texas
I’m not understanding why you wouldn’t just wire in a pertronix and a 30 dollar pertronix coil and Be done with it.

From that point, you really only have three probable wires to Sus out.

The two BY wires from the starter and confirmed ground on the distributor.

I know throwing 150 bucks at a situation isn’t for everyone, but if you are going that route anyway, just start fresh.

When I had a no spark at the coil situation the other day with my trollhole distributor, it was in fact the electronic igniter in distributor.

I replaced the distributor with an older distributor with performed installed and it fired right up.
 
Joined
Jan 5, 2017
Messages
3,637
Location
Charlotte, NC & Alexandria, VA
The reason is very simple. I have a 40 that won't start reliably, and when it does, it won't run. There's more the the truck than just the ignition system.

I can't verify the problem is the ignition, the fuel system, both, or something else, like a grounded circuit somewhere.

I don't believe in replacing every part I can find until the problem I''m trying to solve goes away.
 
Joined
May 14, 2016
Messages
2,045
Location
Arizona
The reason is very simple. I have a 40 that won't start reliably, and when it does, it won't run. There's more the the truck than just the ignition system.

I can't verify the problem is the ignition, the fuel system, both, or something else, like a grounded circuit somewhere.

I don't believe in replacing every part I can find until the problem I''m trying to solve goes away.

Some people have had many issues with a faulty ignition switch. It provides reliable voltage to ignition and if it is worn out it can become intermittent.
 

Users who are viewing this thread

Top Bottom