'69 L68 with TI Getting No Spark

[Richard M.]

Re: '69 L68 with TI Getting No Spark

Okay, what is the most likely culprit when the spark comes and goes within minutes!

I decided to fall back and double check that I was not getting any spark by using my timing light. I had to reconnect the distributor pigtail and the TI harnes to the amp pigtail. Damn thing fired right up. Cut it off after only a few seconds and tried again and I'm getting no spark - as shown by my timing light. Wait a couple of minutes, it fires up once again but now hasn't the next few attempts before I decided to come in the house to fire off this update (and my battery is getting weak).

So is there a component more likely than another to exhibit this type of "come and go" behaviour?

Thanks,

Jack

Jack, The last two items you touched are therefore suspect.....the TI harness plug at the module and the Dist plug.

Put your battery charger on the battery while checking the items below.....

The Dist plug is easy to check. Make sure they're clean and tight.

The female terminals in the TI module harness plug are common intermittent problem areas. The 3 female terminals in the rubber module plug can get pushed downward or the terminals can get loose or corroded. I would remove the module from the car and carefully inspect the terminals. Ensure they are not pushed down.


If all looks good, remove the rear cover and inspect the 3 wire terminals which are connected to the circuit board. If it's the original Delco module, be VERY careful you don't break the male soldered terminals on the circuit board while checking the 3 connections.

Gray is from the Dist PU coil, Brown is Power from the Ign Switch, Black is output to the Coil+.


It could be that simple engine vibrations are making something loosen.

Rich

[Jack O.]

Re: '69 L68 with TI Getting No Spark

Bad ground to the negative side of the coil! I haven't isolated it exactly yet but believe its the ground wire mount to the amp although the amp itself seems to be grounded fine. I didn't realize a bad ground can behave in such a manner - come and go that is. I saw that discussed all over here and but it didn't occur to me until last night of how easy it was to check by simply running a new ground wire to the coil.

Thanks everyone again for all the help!

Jack

[Richard M.]

Re: '69 L68 with TI Getting No Spark

Bad ground to the negative side of the coil! I haven't isolated it exactly yet but believe its the ground wire mount to the amp although the amp itself seems to be grounded fine. I didn't realize a bad ground can behave in such a manner - come and go that is. I saw that discussed all over here and but it didn't occur to me until last night of how easy it was to check by simply running a new ground wire to the coil.

Thanks everyone again for all the help!

Jack

Good work Jack. I doubt the ground wire in the harness is broken, just a bad connection at the rad support.

The coil- is a hard ground from the harness via the TI Module case mount bolt and the radiator support ground terminal. So therefore, the TI Module was likely intermittently loosing it's ground as well. Clean everything, use toothed lockwashers UNDER the wire terminals to scratch both the rad support AND the TI Module, and you should be all set.

Ground points shown here in the wiring diagram. Note the source is solely the GND lug ground symbol to the left of the Module depiction. Also make certain your rad support is in fact grounded well. I'm unfamiliar with the C3 ground source, but may be a Harness ground to the Horn Relay mount bolt as well as the chassis frame to lower rad support 7/16" diameter mount bolts. THose get rusty over time.

http://tispecialty.com/articles/66-71diagram.htm

[Jack O.]

Re: '69 L68 with TI Getting No Spark

Given the circumstances of my issue and how it came about, as I described above, I was very much in tune to "okay, all I've done since the car stopped running is re-arrange the spark plug wires and mess with the coil/distributor connections so it has to have something to do with that". We'll I strayed far from there but should not have because it turns out it was the ground wire connector running to the coil! All I had to do is move the wire connector around a bit and I lose my ground. So, all fixed now.

Jack

[Richard M.]

Re: '69 L68 with TI Getting No Spark

Given the circumstances of my issue and how it came about, as I described above, I was very much in tune to "okay, all I've done since the car stopped running is re-arrange the spark plug wires and mess with the coil/distributor connections so it has to have something to do with that". We'll I strayed far from there but should not have because it turns out it was the ground wire connector running to the coil! All I had to do is move the wire connector around a bit and I lose my ground. So, all fixed now.

Jack

Jack, Glad you found it. But a question just to fully understand.

Was it the Black Coil- wire terminal loose at the coil and needed the attach nut tightened, or was it fixed by simply moving the wire around while the nut was tight?

Is it possible you have a aged and possibly internally broken wire? If so, this problem may return.

Rich

[Jack O.]

Re: '69 L68 with TI Getting No Spark

Rich,

The black coil wire was broke, internally, at the coil connector. The breakage of course was not visible but if I moved it around I would get good connectivity. I simply replaced the connector and all is well now.

Jack

[Richard M.]

Re: '69 L68 with TI Getting No Spark

Excellent. So as it appears, one of the last things played around with was the culprit.

Thanks for the final update Jack. Nice work.

Rich