switched ignition power circuit loses 12V when starter is engaged

[scudzuki]

My 72 Dart Swinger ignition switched 12V circuit loses power when I turn the key to the start position (engaging the starter solenoid), then as soon as the key returns to the run position, the switched circuit is hot again.
According to the wiring diagram, that switched circuit connects to the ignition coil, one field on the starter, and the voltage regulator.
I use the coil positive wire to trigger a relay, the battery provides 12V to the relay and the fused 12V relay output provides switched 12V to a 1 wire HEI distro and the MSD Atomic TB FI and fuel pump (the Atomic EFI has a dedicated FP power wire that can control a PWM pump or regular pump like the Walbro with regulator and return line I installed).
It wasn't until I installed the MSD FI that I noticed the FI powers up when the ignition is switched on, then changes to "shutting down" when the starter is engaged. When the ignition is switched off, the EFI displays "shutting down" for a few seconds while it writes self tuning logs to the EFI.
If I switch the ignition to on, wait for the fuel pressure to stabilize and the FI to "boot" completely, then turn the engine over for a second or 2, the engine fires (when cold) and starts when I release the starter.
It won't hot start this way, and it's also simply not right, so I need to find where the switched 12V is going.

It appears the alternator is good; I tested it out of the car, energizing the field with 12V, spinning the armature with a power drill, and measuring 15 plus V between the alt body and positive terminal.

When the engine is running, the alternator is not charging the battery, it's at 12.3V

Could a bad regulator kill the 12V on the ignition switched circuit? To my mind the only place it could be going is shorted to ground, which I suspect would eventually blow a fuse or melt something.

Could it be the ignition switch itself?

Thanks.

 

[scudzuki]

AHA! I think I know what's going on. I was just looking for a new ignition switch (just in case) and Google found an article here describing how to replace the ignition switch which led to to another thread where some member explained about IGN1 and IGN2 on the ignition switch. There are 2 brown wires under the hood that are disconnected, one with a ring terminal near the coil. I suspect this is IGN2 that went to the (now unneeded and absent) coil. I could not test that wire when I first found it 'cause I can't measure the output AND turn the key at the same time easily. I may be on to something.

 

[Professor Fate]

Yeah, you need to connect IGN1 and IGN2 together, and then connect that to the MSD ign. input.

 

[scudzuki]

Another AHA! There is a brown wire with a female blade connector that was near the ballast (when there was one) that is really the wire I'm looking for. I forget what the brown coil wire with a ring terminal was for.

 

[scudzuki]

Yeah, you need to connect IGN1 and IGN2 together, and then connect that to the MSD ign. input.

I was gonna jumper the starter solenoid trigger wire to do the same (before I knew about IGN2) until I realized that the starter would engage as soon as I switched the ignition on. The ignition switch must have a seperate contact for the starter when the switch is in the start position.

 

[plumkrazee70]

Wire IGN 1 and IGN 2 together, that will give you 12v while cranking.

I did this for my EFI conversion, and then added a push button start ona relay. So key on, wait for Fuel Pressure to come up, hit the push button and fire every time, hot or cold.

 

[scudzuki]

Wire IGN 1 and IGN 2 together, that will give you 12v while cranking.

I did this for my EFI conversion, and then added a push button start ona relay. So key on, wait for Fuel Pressure to come up, hit the push button and fire every time, hot or cold.

My car was all whored up when I got it.
It had a CDI conversion distributor plus a new spare CDI distributor (seller was unable to fix it when it quit running) and 3 different coils. I tried to get a spark swapping in different parts. I suspect it was the CDI power supply that went bad as it was never replaced.
The brown wire that went to the ballast is 2 brown wires crimpled into a sincle female blade connector.
Do I have to connect BOTH brown wires to the IGN1 wire, or is just the brown wire coming from the bulkhead connector on the firewall?

Trying to trace the wires from the diagrams in the factory service manual is a PITA when they cross pages. I almost bought a laminated color coded wiring diagram but don't want to waste the money.

 

[scudzuki]

Sooo it was not the single brown wired I traced to the bulkhead. It was the pair of brown wires that disappear into the wiring harness. Now the engine starts while I'm cranking because there is spark and fuel pressure and fuel injection while cranking.

Charging is still fucked though. I reinstalled the Powermaster alternator that that came with the car after I bench tested it following directions I found on YouTube. 12V to the field connectors, spun it with a drill, 19V across the alt case and power stud. Another alt that came with the car only put out 15V tested the same way but that still passes AFAIK.
No charging when installed. Followed the same YT guy's directions for testing in the vehicle. left the blue field wire connected connected the other field terminal from the alt to battery ground, started it, shot up to over 14V. Installed a new regulator, even added a ground from the case to another chassis ground point, battery is draining while running (11.9-12V). Guess I can jumper the alt field terminals to the reg, rule out an issue with the wiring?

Thoughts?

Getting close to test driving it, but I don't want to get stranded on the road.

Gonna create another thread so it catches more eyes.

Thanks.

 

[67Dart273]

That action is completely normal. The ONLY ignition power "when cranking" comes from IGN2, which supplies full battery power to the coil + The INTERESTING and weird thing is, on the newer cars which had factory electronic ignition, the ECU box gets LOWER voltage, because it only gets power (when cranking) by backfeed through the ballast to the ECU!!!

One thing you do NOT want to do, is to imitate that by using the yellow "start" signal which engages the start relay. That will cause backfeed to the relay when running. If you have, say, a stick car with no clutch switch, or when you have the auto in park or neutral, the starter will stay engaged when running