Problem with ignition wiring on 1972 C10

[herronnpd]

Ok so I have a 1972 Chevy C10 Step side that has been sitting for a while. I'm having problems with getting fire at the plugs. I'm not for sure if the wire I'm using from the firewall is correct. It seems as though none of my wiring matches any wiring diagram that I can find. I have a pink wire that I have traced back to the ignition that I'm using for a 12 volt wire, then I have a yellow wire back to starter, which are on the positive side of the coil. Then the wire coming from the distributor on the negative side of the coil. I have replaced the coil, distributor cap, rotor button, and points and condenser! I'm puzzled? Any help would be greatly appreciated!

[airdale94]

If you have points your hot for your coil should come off your starter wiring harness not a dedicated 12v. from your fuse box. It's a resistor wire that is white with a yellow stripe or purple and white. Then should be yellow going to your coil. It only carries 6v to avoid burning up your points. Check for spark directly out of your coil. Did you set gap on your points?

[landy]

Here's a link to a very nice color-coded wiring diagram that one of the members did. It's on the electrical forum.

http://67-72chevytrucks.com/vboard/s...d.php?t=185856

[herronnpd]

Just for more info this is an all original truck was bought new in 72 and nothing has been changed on it but there's not a white and purple wire. There's a solid purple wire running to the starter. Yeah set the point gap a 19
There's no spark coming out of the distributor! Thanks for the wiring diagram but for some reason or another the color of my wiring is different. the pink wire is marked as a resistor wire. Should I wire it to the starter? Then back to the positive side of the coil?

[VetteVet]

Here is a diagram of the ignition from the engine side of the firewall block to the coil. The orange white purple wire is a resistance wire that prevents too much voltage to the coil during normal running.

It ties into the yellow wire from the starter which supplies 12 volts to the coil only during starting. After starting the 12 volts on the yellow wire drops to 9 volts due to the resistance wire.

Check your coil positive terminal for voltage with just the key on. If you have it then the coil is bad or the distributor is the problem.



The orange white purple wire is a cloth covered wire but due to aging it may look like this.



It is right next to the no.2 blue wire.

[herronnpd]

Thanks Vette Vet, that helped out a lot. Will make some changes in the morning!

[herronnpd]

okay all the wiring is correct now, but with the key on I have 15 volts on the positive side of the coil? The coil is new still no spark out of the distributor. I've replaced the rotor button, distributor cap, points and gapped them at 19. The ignition timing is correct. Is the distributor bad? Need help?