[MidnightAuto]

Just concluded fixing one thing, and now I have a firing problem out of the blue. Tried to diagnosis but am coming up short so looking for some guidance. Went to start car after sitting for a week. With gas evaporating, sometimes it can take a bit. But it never started. Checked gas and am getting fuel.

I noticed that my msd 6al box was not lit up with the key in on position. It does blink 5 times initially, but then goes out. It’s usually lit up in the on position after the blinking. So I presume it’s a spark issue. I take the coil wire from dizzy and ground it and can see spark arcing when car turns over. So coil is fine. Then I pull a plug and leave in the boot to watch for spark at gap. No spark. So I would think this is now a dizzy issue. I do have a petronix II, which I know others have had issues. I have never had an issue (and my understanding is that it’s usually related to a poor ground, which I have lots of ground straps everywhere). In any case, I just happen to have a new petronix II as a back up and swapped it out. Still no start, and the msd led is still not lighting up with key in on position. So to sum:

Won’t start
Msd 6al led not lighting up in on position
Coil seems to be firing fine
No spark at spark plug.

Where do I troubleshoot from here?

[64speed]

There is a guide in your MSD instruction about grounding the white wire to check for spark. The red light on mine does not stay on after the 5 flashes either. Only stays on when it’s running.

[mgarblik]

If your getting a strong blue/white spark from the end of the coil wire at the distributor, the MSD and the Pertonix unit is functioning. The Pertronix "Module" is triggering the MSD. Personally, I would just use a set of points to trigger the MSD to eliminate a failure down the road. Spark from coil should jump a 1/2" gap and have a sharp zap sound to it. So if you have that, but no spark at the end of a plug wire, the only thing left is a defective dist. Cap, (unlikely), or a defective rotor. (more likely) I would look for a broken or loose contact tang on the rotor.

[jww]

I've had condensers go bad suddenly,, too...

[MidnightAuto]

Ok thanks guys. I was not sure of the interplay with the msd and the petronix. That explanation helps. Since I am running a petronix I don’t think I have a condenser? Isn’t that connected to points?

Really strange - it’s a relatively new cap and rotor and they both look good. Have been working fine for the 6months old that they are. I’ll get back at it tomorrow and see if anything comes of it. I was going to bypass the msd altogether but wit the info above, that seems like a fruitless test…

Coil is arcing strongly with blue white flame, it does have a few second delay from when I start to crank the motor, but I assumed that was normal…

[MidnightAuto]

Here s an update. I decided to bypass the msd box and the car started. I’ll skip the part where a spark plug connector broke in half, and all my gauges stopped working, along with my new fuel sending unit apparently reading wrong and the car running out of gas. So after fixing all that krap, it seems the car is running again sans an msd box. I should have listened to all the reviews on that box.

Thanks again guys for weighing in.

With all this electronic shenanigans going on, my eye did start to stray towards a progress ignition dizzy. So cool. Maybe Santa will get me one.

[MidnightAuto]

Here s an update. I decided to bypass the msd box and the car started. I’ll skip the part where a spark plug connector broke in half, and all my gauges stopped working, along with my new fuel sending unit apparently reading wrong and the car running out of gas. So after fixing all that krap, it seems the car is running again sans an msd box. I should have listened to all the reviews on that box.

Thanks again guys for weighing in.

With all this electronic shenanigans going on, my eye did start to stray towards a progress ignition dizzy. So cool. Maybe Santa will get me one.

[MidnightAuto]

Ok well the story did not end. The car started backfiring consistently on the beat. Having seen this movie before I knew it might be crossed wires. But actually that was not it. After some pain with plug location on cap I pulled all the wires off and started from scratch. In doing that I discovered that the same node in the distributor cap as the broken plug connector was totally oxidized and crusty down the female hole. No doubt this was causing the backfire on time. Here is my question, it’s a 6 month old msd distribtor cap. Every other female hole is bright brass. Why would one plug go off the rails so much that it would make this plug inoperable? I would expect they would all wear equally? It was 7 shiny brass holes and one green crusty hole. Why only one? After 6 months?

[MidnightAuto]

Ok well the story did not end. The car started backfiring consistently on the beat. Having seen this movie before I knew it might be crossed wires. But actually that was not it. After some pain with plug location on cap I pulled all the wires off and started from scratch. In doing that I discovered that the same node in the distributor cap as the broken plug connector was totally oxidized and crusty down the female hole. No doubt this was causing the backfire on time. Here is my question, it’s a 6 month old msd distribtor cap. Every other female hole is bright brass. Why would one plug go off the rails so much that it would make this plug inoperable? I would expect they would all wear equally? It was 7 shiny brass holes and one green crusty hole. Why only one? After 6 months?

[steve25]

That bad plug wire you had was not letting the spark go where it should for the amount of time before you found it which is why terminal 7 is shot.

It’s just as well that you need to replace the cap because I bet that the cap now has some carbon tracking going on between the terminals on either side of numbed 7.

[MidnightAuto]

I guess that makes sense. I thought I maybe broke the brass end in the plug boot when I was pulling off the cap, but it was highly oxidized so perhaps I busted it when I put the plugs on the first time….