Classic Mustangs (Tech)Technical discussions about the Mustangs of yester-year.
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Here's the problem, the wiring on my sons 68 Mustang has been butchered by people who had no idea what they were doing! The ignition switch was cutting out so we went to replace it & found an electrical nightmare, we sorted it out & have it wired to the way schematics show it & pictures I've found. Now it won't start at all.
Here's what I have:
* First the car turns over but there's no spark.
* 0 volts at the coil + with the key off.
* 12.7 volts at the coil + with the key on.
* 10.7 volts at the coil + while turning over.
* 13.3 Volts at I (ignition) post on the solenoid when key switched on.
* 0 volts to the S (starter) side when key is on.
* 10.5 volts to the S (starter) side when turning over.
No spark at all, checked with a grounded plug & my timing light.
Jumped a lead from the battery + to the + on the coil & still no spark.
Any clues, suggestions or ideas?
We have the pink resistor wire but can't find what it's purpose is, can this be the issue? I haven't traced it to it's source yet.
Mark & Aaron
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First question: are you running points, or electronic ignition?
The pink resistor wire is supposed to run from the ignition switch to the firewall connection, and then a standard wire runs to the coil +. This should be the only source of power to the coil when the switch is in the "on" position. The resistor wire portion is supposed to drop voltage to the coil to keep from burning out points. If you're running electronic ignition, cut the resistor wire out.
If you're running points, the "I" terminal on the solenoid is supposed to feed back to the coil +. This terminal is only connected to B+ when the the ignition is in the "start" position (while the solenoid is activated). This gives full battery voltage to coil + while cranking, bypassing the resistor on the wire from the ignition switch, which aids in starting with a points system. If you're running electronic ignition and have disabled the resistor wire, this wire from the solenoid is redundant.
All that said, your wiring sounds right based on your voltage readings. You should be getting spark, assuming the distributor innards are working properly and the coil is functioning. Those are the places I'd start looking.
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