engine and drivetrain Melting coil resistance wire

[LateApex]

This is my attempt at a first start up after much work.

 

While cranking the engine (using a remote starter switch to the diagnostic plug) to confirm baseline timing, the insulation on the resistor wire started melting.

 

I believe I have the Black coil, but I'm not sure because the PO painted it.  Here are my resistance readings:

 

(The meter, when the leads are connected to each other reads 0.6, so I assume I need to remove that number from the low-end readings.)

 

Using the "200" setting

Coil + to - = 1.1 (or 0.5, adjusted)

Resistance wire = 1.6 (or 1.1 adjusted)

 

Using the 20k setting

Coil + to center post = 5.88

 

From what I have read, all those readings sound within spec and would indicate a functioning coil.  While cranking with the timing gun attached I am getting a timing signal on the #1 plug wire.

 

I do not have an additional wire running from the solenoid to the coil and didn't before my work when the car started and ran fine.

I am running a "coil signal" fuel pump relay with the signal wire attached to the negative side of the coil, which is working correctly. 

Additional info: the resistance wire has 12.6v at the coil +

 

I'm thinking that the 35 year old resister wire cant handle the 12v load during extended cranking.  Should I go with regular wire and a block resister? 

Edited February 25, 2016 by LateApex

[FunkyLaneO]

Do you have anything else attached to the positive lug on the coil? It sounds like something is backfeeding (something high draw like a starter).  Are you sure the starter bypass wire is disconnected from the starter? if it is on the wrong lug on the starter it will do exactly what yours is doing.  The4 thing with that ignition circuit is that it is an unfused circuit and the greatest resistance is in that resistor wire, so if there is a short or overload it will roast that wire, your coil should not be able to do that (even if the wire is more than 35 years old).

[LateApex]

Nothing else attached to the coil positive lug.

The lug at the top of the solenoid, which I think is the connection for the bypass wire, is empty.  Connections on the solenoid include the battery cable, a second red, large gauge wire which I believe connects the battery cable to the engine compartment harness (my battery is in the trunk) and rectangular plastic female lug connector.

 

I found a graphic that showed that, with the black coil, the ignition wire was 9v when ignition on and no starter.  Is this correct? because mine reads 12.6v.

Edited February 25, 2016 by LateApex

[ray_]

Are you sure you have a resistance wire? You have a ballast resistor, I'm inferring. Is the wire insulation melting at the resistor connection? If so, I might be inclined to say it's almost normal. Those resistors get hot. It's what they do.

 

Cheers,

[LateApex]

Are you sure you have a resistance wire? You have a ballast resistor, I'm inferring. Is the wire insulation melting at the resistor connection? If so, I might be inclined to say it's almost normal. Those resistors get hot. It's what they do.

 

Cheers,

No, no ballast resistor, yellowish clear-insulated wire runs to the + terminal.  I only included that drawing to show the voltage difference.  When measured, the wire reads about 1 ohm of resistance.  I have been doing much reading today and I see where most coils measure around 3 ohms.  As mentioned above, mine reads 0.6 ohms.  I am thinking the very low resistance in my coil is overwhelming the resistance wire.  I am becoming more convinced I have a bad coil.

Edited February 25, 2016 by LateApex