Ignition issues

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Glanceb

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Firstly please excuse any simple mistakes that my come accross in explaing the issue, I'm new to working on cars and have run into a couple of problems on my e9.

The issue that I am having is concerning starting. The car is a 2800cs with a retro fitted 3.0cs engine. There was an alarm system on the car but it didn't seem to be connected to anything so I removed it. The following is what has happened

1: Car starting perfectly no issues
2: Tank goes dry, battery removed and reinstalled
3: Upon starting now the starter is turning there is petrol being delivered but I don't seem to have a spark.

The question is are there any steps you can follow to see if there is a problem with the coil.

I have 12v on one side of it when starting and what seems to be six on the other. I have checked the points and they are functioning correctly and the high tension wire doesn't seem to be corroded.

There is one loose wire connected to what seems to be a capicator on the body (that must go to one side of the coil) but it has never been conected and the car ran without it connected in the past.

The only difference is the alarm that I removed which was activated by a key swith on the boot, I traced the switch wires to the engine and they were connected to nothing.

There is an alarm light in the cabin that has an earth wire and another wire with no voltage, (I can assume this was only to make the lights flash in the cabin)going to it?

I'm really just looking for a sequence of steps to go through to try and find the problem, and an explanation of how to check the coil is working.


As always the experience in the forum has been a great help to me and I appreciate your input.

Best regards,

GlanceB
 
Firstly please excuse any simple mistakes that my come accross in explaing the issue, I'm new to working on cars and have run into a couple of problems on my e9.

The issue that I am having is concerning starting. The car is a 2800cs with a retro fitted 3.0cs engine. There was an alarm system on the car but it didn't seem to be connected to anything so I removed it. The following is what has happened

1: Car starting perfectly no issues
2: Tank goes dry, battery removed and reinstalled
3: Upon starting now the starter is turning there is petrol being delivered but I don't seem to have a spark.

The question is are there any steps you can follow to see if there is a problem with the coil.

I have 12v on one side of it when starting and what seems to be six on the other. I have checked the points and they are functioning correctly and the high tension wire doesn't seem to be corroded.

There is one loose wire connected to what seems to be a capicator on the body (that must go to one side of the coil) but it has never been conected and the car ran without it connected in the past.

The only difference is the alarm that I removed which was activated by a key swith on the boot, I traced the switch wires to the engine and they were connected to nothing.

There is an alarm light in the cabin that has an earth wire and another wire with no voltage, (I can assume this was only to make the lights flash in the cabin)going to it?

I'm really just looking for a sequence of steps to go through to try and find the problem, and an explanation of how to check the coil is working.


As always the experience in the forum has been a great help to me and I appreciate your input.

Best regards,

GlanceB
 
There should be at least two wires on the primary side of the coil--one is the "start" circuit which does not have a ballast resistor in it (voltage direct from the battery through the solenoid so the spark is hotter when starting) and the "run" circuit, which has the ballast resistor in the circuit to keep the coil voltage lower to prolong its life. I believe the "capacitor" to which you refer is the ballast resistor. My 74 coupe has a transparent wire connected to the coil primary for the run circuit...this is a resistance wire, hence the ballast resistor is not used. I don't believe this wire was used before 1974, so I would be suspect if your ballast resistor is disconnected. Hook it up and see what happens...
Bill
74 3.0 CS, 4310008
 
There should be at least two wires on the primary side of the coil--one is the "start" circuit which does not have a ballast resistor in it (voltage direct from the battery through the solenoid so the spark is hotter when starting) and the "run" circuit, which has the ballast resistor in the circuit to keep the coil voltage lower to prolong its life. I believe the "capacitor" to which you refer is the ballast resistor. My 74 coupe has a transparent wire connected to the coil primary for the run circuit...this is a resistance wire, hence the ballast resistor is not used. I don't believe this wire was used before 1974, so I would be suspect if your ballast resistor is disconnected. Hook it up and see what happens...
Bill
74 3.0 CS, 4310008
 
When you say the points are working correctly how did you test them? And can you be more specific on the coil voltages, was the engine turning oever at the time? You should have something close to 12v on one side of the coil and with the engine turning over you could see something like 6v because the points will be opening and closing and most meters integrate (average) the voltage. However, when the ignition is on but the engine is not turning over you should see 12 volts on both sides of the coil (points open, most likely) or 0 volts if the points are closed.

The ballast resistor is not needed if you have a newer coil with an internal ballast or if you have certain types of electronic ignition controllers.

If you want to do a simple coil test, unplug a spark plug wire and put a plug in it. Then take a piece of wire and wrap it around the plug threads on one end and connect the other end to a ground (body bolt, engine bolt, or negative battery terminal. Crank the engine while watching the plug, you should see it sparking every other rotation of the engine. Please don't let the plug get too close to the carbs as the open spark could start a fire. This will pretty much test the entire path to the plugs.

It is pretty rare for a coil to just go bad all at once. Normally they just get weaker and weaker.
 
When you say the points are working correctly how did you test them? And can you be more specific on the coil voltages, was the engine turning oever at the time? You should have something close to 12v on one side of the coil and with the engine turning over you could see something like 6v because the points will be opening and closing and most meters integrate (average) the voltage. However, when the ignition is on but the engine is not turning over you should see 12 volts on both sides of the coil (points open, most likely) or 0 volts if the points are closed.

The ballast resistor is not needed if you have a newer coil with an internal ballast or if you have certain types of electronic ignition controllers.

If you want to do a simple coil test, unplug a spark plug wire and put a plug in it. Then take a piece of wire and wrap it around the plug threads on one end and connect the other end to a ground (body bolt, engine bolt, or negative battery terminal. Crank the engine while watching the plug, you should see it sparking every other rotation of the engine. Please don't let the plug get too close to the carbs as the open spark could start a fire. This will pretty much test the entire path to the plugs.

It is pretty rare for a coil to just go bad all at once. Normally they just get weaker and weaker.
 
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