No Spark on 1978

[wgwollet]

Hello, thanks to all in the past who replied.

I found a bad ignition switch, and need to replace, but in the mean time, I found no 12 volts to fuse #12 (counting from front of car), that feeds the rear CDI. The 12 volts comes from the ignition switch which I troubleshooted as bad. So I jumped fuse #11 to fuse#12 to power up the rear. Then I had a bad delayed action relay (relay used to run engine 3 sec after shut down), so jumped that.

Now I get power to CDI box, but still no power to plugs? I get a spark when engine turned off but not during cranking...I replaced the distributor cap and rotor, green wire to distributor is OK. Some say a CDI box that makes a humming noise, which mine does is not a true test of working correctly....I do not have another SC CDI box to try...I did try spark from coil but I think it was not correct, because I seen spark at number 6 wire only when switched turned off...is the ignition switch a problem still after jumping, I think 12 volts is needed no matter where it come from, yes?

Any ideas..

[jwasbury]

With all the jumpering of wires, you need to verify that the CDI gets power not only with the ignition switch in the "run" position, but also in the "start" or "cranking" position. Of all those fuses up front, there are only a couple that fit that criteria. Most of the 12v circuits disconnect when cranking, so as to maximize the cranking amps going to the starter. Could be you've tapped into 12v that is live only when the key is in the "run" position, but the the "start" position. Check it out.

[T77911S]

if you are jumping pin 30 to "L" at the relay and you are getting 12v to the CD, nothing else matters as far as power. put a test light on the 12v line to the CD. a MM does not provide a load and can give you a false reading. check light at the battery, should be that bright at the CD.

12v does not go thru the fuse up front to the relay in back. it goes to the bottom only, then to the relay.

check for good power at pin 30 at the relay, with a test light.

a Cd can "whine" and still be bad. if mine made noise and i had to guess, i would guess bad coil, then CD. a blaster coil is around $45. BUT, i would make sure other wiring is good. also, the dist can be bad. pull the connector at the CD. ohm the 2 wires to the dist. i think it should be around 600 ohms. (i should really check mine cause i keep telling people this).
pull a plug wire and put a plug on the end and ground it while someone else starts it to check for spark. you can also try connecting a timing light and see if it triggers.

it seems odd that you would have a bad switch AND problems else where.....

[wgwollet]

Thanks guys, really appreciate the response.....