Strange ignition issue

[DSMRossi]

I just put in a rebuilt 360 and completed reworking the harness. 43 years of people tapping connections into an old harness looked like a spider web of crap...

Anyhow, the issue I'm having now is when I turn the key to "run", I have power at the ballast resistor. I have power to the + wire to the coil, but as soon as I connect the - wire to the coil, the system seems to ground out. My test light doesn't read any power to either side of the coil, and the ballast and coil get warm. Anybody experience anything similar?

The ecu grounds to the firewall when it bolts up obviously... I'm at a loss

 

[1969383S]

You will need more than a test light when others have created this havoc!

You did not mention what year and original combo you are working with!

 

[DSMRossi]

73 with a 5 pin

 

[Rapid Robert]

I just put in a rebuilt 360 and completed reworking the harness. 43 years of people tapping connections into an old harness looked like a spider web of crap...

Anyhow, the issue I'm having now is when I turn the key to "run", I have power at the ballast resistor. I have power to the + wire to the coil, but as soon as I connect the - wire to the coil, the system seems to ground out. My test light doesn't read any power to either side of the coil, and the ballast and coil get warm. Anybody experience anything similar?

The ecu grounds to the firewall when it bolts up obviously... I'm at a loss

sounds normal to me. power to/thru the ballast/coil is being grounded by the ECU, then when the ECU is triggered by the dist pickup it opens that circuit making the coil magnetic field collapse creating the spark. its like an intake manifold can have near zero vacuum on a gauge at WOT which would be the same thing as yours with the current flowing (& you know it is flowing cuz the coil/ballast are getting hot. On a side note, is this an OE ECU with a functioning 5th pin? & if so it requires the 4 terminal (dual) ballast. Confirm that the red/green and the blue yellow ECU terminals are being fed in "start", stick a pin in there.

 

[DSMRossi]

It was normal.

I hooked a test light up to the coil and turned the motor over and got nothing.

What I ended up doing was leaving the light connected, leaving the car in "run", and moving the distributor back and forth so the reluctor was bouncing back and forth on a point. I loosened up the 5 pin connector and sure enough the light started flickering.

I cleaned up all the contacts on the 5 pin connector and the test light flickered as the reluctor rolled around trying to start, but still no go.

Checked resistance at the coil and it was low - around 8. Swapped it with a coil that was giving me a 12.5 reading and she fired right up!

Need a couple fittings for the new carb before I can really run her, but it's all set now.

Thanks!!!