No spark...

1411506 · 05-01-2008, 08:42 PM

I know this had been done to death, and my son just told me that there's no stupid questions...just stupid people...
So, bearing in mind that I'm a stupid people and a 911 newbie, can someone please guide me through some troubleshooting to figure out why I have no spark.
A little background - I got this 911 in November in boxes, so I have never heard it run. It's a carbureted 1970 T.
Have spent the last 5 months putting it back together and it's finally at the stage where it can be started.
It cranks, and is getting fuel - but no spark to the plugs.
Now what....
I did search, but most of the info I found was way over my head....if there are threads out there that I missed, with simple step by step troubleshooting guidelines, please point me in that direction.
Thanks in advance, Rob

Eagledriver · 05-01-2008, 08:52 PM

Rob,

If I'm not mistaken your car has a CDI system with 3 pins on the ignition box. These boxes fail sometimes. You can check the box a couple of ways. Turn on the ignition switch without cranking the engine and you should hear a very high pitched hum from the box. (you might have to pull the fuse for the fuel pump so you can hear the ignition box without the noise from the pump). If you (or your son with better hearing) can't hear the tone then the box is probably not working. You can also test the box by grounding and ungrounding the lead that goes to the points. When you do this you should get a spark from the coil.

-Andy

rennworks · 05-01-2008, 10:44 PM

Rob, ck the points next. Make sure the contacts are not corroded.

1411506 · 05-02-2008, 06:49 AM

Thanks for the advice so far....after some research on this site, I've discovered that the cdi box is actually a permatune...so no noise.
The permatune is getting 12 volts when the ignition is on, and after doing the bench tests suggested in this thread CDI Box Troubleshooting Help it passes.
I've also tested continuity on the wires from the permatune to the distributor and coil - both OK.
Points look good.....no corrosion and adjusted correctly.
Bench tested the coil and seems to be ok - I'll check the coil installed later on today when I have a helper.....

3.2 CAB · 05-02-2008, 09:17 AM

Son watches too much South Park. This is bad, mokkkayy?

1411506 · 05-02-2008, 01:53 PM

We removed a plug and plugged it back into a plug wire. Grounded the threads while cranking - no spark
We looked at points while cranking - no spark.
Not sure what to try next.....
Would welcome any input.

1411506 · 05-02-2008, 05:21 PM

Took everything out - the harness, the coil the cdi, etc. Checked/cleaned grounds, re-installed everything - yehaa, it started.
Now I don't have to listen to other peoples 911's on youtube.......
Thanks for the advice.