MG T-ABC

I read the instructions from both the box, and here http://www.ttalk.info/Tech/PerPosGndWiring.htm on how to wire up the Pertronix kit for a positive ground car, okay no problem.

How ever, as I said in the subject line when I turn the key off the motor keeps running! I'm guessing some sort of feed back from the generator... to stop the motor I have to pull the wire off the coil.

How can I correct this please, any ideas? Do I need some sort of Diode or some electronic gizmo in line?

Pat

Ignition timing changes significantly when you follow instructions. Did you use a timing light and adjust timing?

When key turned "off" the power should stop going to coil from the ignition switch.

You are still detonating fuel. Try leaning the mixture and cooler plugs to shed heat and eliminate a hot spot.

Not all plugs are equal. Some are designed to stay hotter than others. A hot plug can cause run-on (dieseling).

Is it running normally, or is it just dieseling? I don't have a lot of experience with Pertronix but if it continues to run normally then there must be a wiring issue somewhere. As Duncan noted, the ignition switch should kill power to the coil. Therefore removing the wire should make no change once the key is in the OFF position. If there is indeed power going to the coil at all times then disconnect the battery until you figure it out. Fire hazard! A bad switch is also a possibility.

Yes, it keeps running as normal and good point(s). I'll investigate further thanks. Pat

Are you using a standard ignition warning light set up - 2.5?v bulb plus resistance in series at the bulb holder?

If more than "design" current is passing from the generator back through the ignition switch to the battery, then it can continue to power the LT side of the coil after the ign switch is turned off. Ammeter will not show charge in this circumstance (I think).

Can also have this behaviour if there is problem with cut out in voltage regulator. If that is the case then the ammeter will show charge as the engine runs on (again I think).

I found the reason the motor did not shut down. I took a 9V battery and connected it to the wire from the ign switch (that feeds the pertronix directly as wiring for a positive ground Pertronix is not normal) and the other end of the battery via a test light to ground, and the test light lit dimly... rats.... I know enough about electronics to know that there must be a short somewhere in the system. This scares the &$&#^^ out of me as I am poor enough as it is with wire stuff, let alone finding a small short - that has to be found.

I was going to remove all the wires from the ign on terminal and start tracing each one, unless anyone knows of a special tool that will pin point the short for me
Pat

I suspect your right in nominating feed back from the generator with the Pertronix installed. will it switch off normally with the generator disconnected?

Not sure if I follow what you did. Did you disconnect a wire that was running from the ignition switch to the Pertronix and connect it to one terminal of a 9V battery and the other terminal via a test light to chassis ground?

There is a path to ground from the ignition switch via the ign warning light and then the generator. That is why the warning light illuminates when the ign switch is turned on. You may possibly have just confirmed this path.

Be careful with polarity if you are introducing a second battery into the system.

Good points, I'll keep both in mind.

When I use the 9V battery I disconnect the main battery. This way I can isolate individual wires with a power source.

What I did was disconnected the power feed wire from the ign switch, to the coil and hooked up the wire from the coil to the + of the 9V battery and the test light to the - of the 9v battery then grounded the test light.

Really good point on the ign warning light, but if that is the issue then why does the car keep running when the key is turned off Ahh the mysteries...
Pat

Sorry but I am still not clear on what you did with the 9v battery. You say you disconnected the wire from the ign switch to the coil. With a Pertronix on a positive earth car I did not think any such wire existed. Isn't the Ignitor module powered from the ign switch? And then the Ignitor module connected to the coil negative terminal? That is, the module is wired between the switch and the coil? Isn't the other + side of the coil earthed?

No wonder your a bit confused, I goofed a bit, sorry

The "+" from the coil goes to earth
The "-" from the coil goes to the pertronix (black and white wire)

The black wire from the pertronix is spliced on to a white wire that in turn goes to the fuse block. This is the wire I cut to put on the 9V (is really a big square 6V) battery so I can easily trace the flow of power with out using the full force of the cars battery.

I puttered around on it this afternoon, and have solved the short issue, but created another one so to speak. I found that when I disconnected the power wire to the ign warning lamp all problems went away. Now I just have to figure out where to get power from for the ign idiot light.
Pat

Thanks. Now my question is where is this fuse block and where is it getting its power from?