What would cause the spark from the coil when the key is turned to run(on)?

 

With stator vane directly opposite PU module when ignition was energized by turning the key to on/run.

 

So if mine does it no matter what, then I have a short in the dizzy?

I connected the timing light while cranking. It is at the 10* mark while cranking.

 

I just tried to start it and it spit out of the carb and burped out of the exhaust at the same time.

 

I just tried a new ignition switch, ignition module, different harness from the ignition module to the dizzy, and did a compression check (155 to 165psi) and still the same thing. Will low voltage on the coil cause this? I am going to get my voltmeter now and will check it when I get home. Thanks for all of the help.

 

I don't think so. (BTW, very nice diagnostic scans, Mil1ion!) When you turn the key to the 'On' position the ignition switch feeds a reduced voltage (because of the ballast resistor) of 6 to 8 volts to the 'Batt" side of the coil (see upper right of Mil1ion's diagram). It also feeds full battery voltage to the ignition box on the red wire. The ignition box pulls the coil to ground, causing current to flow through the coil primary windings, charging up the coil. This should not cause the coil to discharge. (If you were to now turn the ignition key to the 'Off' position at this point, the magnetic field of the coil will collapse and that will cause the coil to fire.) But since you now turn the ignition key to the 'Start' position and the engine begins to crank, the ignition switch now feeds full battery voltage to the 'Batt' side of the coil for starting, and it also feeds full battery voltage to the ignition box on the white wire.
Then when the steel tooth of the stator interupts the magnetic field of the magnetic pickup coil inside the distributor, a current is sent to the ignition box. When the ignition box sees this current it then 'ungrounds' the 'tach' side of the coil, which causes the magnetic field of the coil to collapse, causing a spark. (Additionaly, if the ignition box sees battery voltage on its white wire, it knows the engine is being cranked, so it delays 'ungrounding' the coil for approximately 7-9 degrees, which in effect 'retards' the timing to make it easier to start the engine
That's good. So that tells us the ignition system is putting out enough voltage to fire the timing light and that the number one plug is firing at 10 degrees. Is that 10 degrees BTDC or ATDC?
And since you have swaped distributors, how are we sure it is TDC on the compression stroke and not TDC on the exhaust stroke?
That tells me that the spark is happening at the worng time.

Someone else feel free to jump in here with something we may have overlooked.

 

The coil fires when the key is turned to the on/run position but does not fire when the key is turned bak to the off position. 10* advanced. I made sure that I kept the rotor on the dizzys when removed/installed. I am absolute the firing order is right and the dizzy is not out 180*. I will check the voltage at the white wire of the control box in the morning. The coil seems to be working opposite of normal.

 

I checked the voltage at the coil. The battery side is 5.30 and the tach side is 1.5. On the ignition module the red wire and white wire are opposite colors at the plug. The key in on/run the white wire on the plug coming from the firewall has 12v the red wire coming from the firewall has 0v. The resistance from the battery side of the coil to the red wire from the firewall to the module is 9.4 ohms.

 

That's interesting. The coil shouldn't fire when current is APPLIED to the primary windings of the coil. The coil should fire when current to the coil's primary windings is suddenly turned OFF. Maybe we have a wiring issue.
Here's something that you can do to check out all the feeds to the coil at once:
1.) Disconnect the small wire from the starter relay on the inner fender. (This will keep the engine from cranking when you turn the ignition key to Start/Crank.

2.) Measure the voltage of your battery and write the voltage down.

3.) With the ignition key in the Off position, and without disconnecting the two wire connector to the ignition box, measure the voltage on the white wire and the red wire, and the Batt terminal of the coil.

4.) Turn the ignition key to the Run/On position and remeasure the voltage on the white wire, the red wire, and the Batt terminal of the coil.

5.) Finally, have someone hold the ignition key in the Start/Crank position (engine should not crank with the starter relay disabled) and remeasure the voltage on the white wire, red wire, and at the Batt terminal of the coil.

So you should end up with:

Baterry Voltage = xx.x

Key Off voltages: White = xx.xv, Red = xx.xv, Coil = xx.xv

Key On voltages: White = xx.xv, Red = xx.xv, Coil = xx.xv

Key Start voltages: White = xx.xv, Red = xx.xv, Coil = xx.xv

Let us know what you get.

 

Battery 12.4v
Key off: white 0v, red 0v, coil batt 0v, coil tach 0v
Key on: white 11.3, red 0v, coil batt 5.3v, coil tach 1.7v
Key start: white 0v, red 11.3v, coil batt 5.1, coil tach 1.7v

 

Okay, battery has adequate voltage.
Good! There is no voltage getting to the coil with the key in the Off postion.
I'm confussed here. The ignition box's Red wire should be within 1.0 volts of battery voltage with the key in the On/Run position. If the White harness wire crosses to the box's Red wire I guess we are okay here.
But the Batt terminal voltage is low. It wants to be in the 6-8 volt range with the key in the On/Run position. Anybody know the spec for the ballast resistor? Mil1ion's diagnostic procedure (fig 5.20) shows how to measure the resistance of the ballast resistor but doesn't give a spec. My wiring diagram shows 1.05 to 1.15 ohms. Maybe you better remeasure the ballast resistor's resistance according to Mil1ion's fig 5.20 example for probe placement.
There is also a problem here. When the ignition key is in the Start/Crank postion the voltage available to the Batt terminal of the coil should be within 1.0 volts of battery voltage. When cranking the engine battery voltage should be fed directly to the coil, bypassing the ballast resistor. This is done so that as the starter motor sucks up voltage there will be enough voltage available to the coil for a healthy spark.
Carefully check the two circuits (Start and Run) that feed the Batt terminal of the coil. Check all connections in thses circuits for clean connections and for any deteriation in the wires. Also check the resistance in the primary side of the coil. Any one got the spec on the coil primary resistance?
Might want to temporarily run a jumper wire from the battery positive post directly to the Batt terminal of the coil (which will temporarily bypass the ballast resistor and the two coil feed circuits) and see if that will help it to start.
As Mil1ion posted,
Blue spark = Good,
Yellow spark = Bad.

 

Taking the measurement according to mil1ion chart, I get 9~10 ohms.

 

That measurement is with the ignition box two-wire plug disconnected, the coil wire disconnected, and with the ignition switch in the Off posoition?

If it is, we have way too much resistance in that circuit. Temporarily run a jumper wire from the battery positive post directly to the Batt terminal of the coil (which will temporarily bypass the ballast resistor and the two coil feed circuits) and see if it will start with this jumper wire connected.

 

Would this resistance cause the backfiring through the carb and exhaust?

 

Yes. A weak spark may not actually arc the plug when the mixture is under compression. Or it may start to ignite the fuel and get blown out. Or it may burn very slowly and end up burning as it is pushed out the exhaust - backfire! I'd pull a sparkplug or two and see what color they are, and if they are wet or dry.

And don't forget, you should see within 1.0 volts of battery voltage at the Batt terminal of the coil when the ignition switch is in the Start/Crank position. With your battery you should see ~11.5 volts, not the 5.1 volts you are seeing. Running a temporary jumper wire from the positive post of the battery to the Batt terminal of the coil should answer that question.