I have L03 Caprice
I had trouble once firing up over last weekend(took 6 tries had spark and fuel). Today go to leave and i could not start. I take a look at the tbi unit its working fine. I the test for spark. there was none-performed with a tester.
Ifollow my flow charts and coil tested fine, pick-up was within spec at 670 ohms. had batt pos at coil-11.9 volts due to cold cranking. that left the module. there wasnt anything i could find on testing it so i had to get a ride to the parts store. stopped at the "vatozone" the test failed in the field category and passed on everything else then she ran it again while i was on the phone it passed-figured it was intermittent...installed new one and still wasnt any spark.I double check every wire and the connections to the coil were a little loose on one side i try to fire and motor turn over slowly but it did and ran fine.
so I take the old module to 4 differnt stores 2 of which had different testing equipment and it tested good at every one. at another "vatozone" the thing tested bad again in the field category but the guy say i gotta scrape this crud off and it passed.
trying to figure if i got;got or just intermittent. idk what the field is.
could my problem be just that the connection was just bad to begin with?

 

Bad connections will cause the ign. not to work. Also keep in mind that there are no dedicated ground wires for the ignition on the older HEI setups. The ground path is thru the dist. base and the intake. If the base, or hold down clam are cruddy, that will cause the ignition system not to fire as well. All the connections, from the plugs, to the hold down screws, to the base and clamp need to be clean or there wont be a complete circuit.

As for the coil, keep in mind that they can test fine, but still be bad. Corona discharge in the secondary can sometimes burn thru the insulation, and allow high tension from the secondary to leak into the primary. The coil will look fine, but when its in operation, it will arc out internally when the engine is under heavy load and the ECM is commanding additional dwell for acceleration. I had this happen on several coils, and it can take the module out with it when it happens.

 

well I tried my old factory one and it didnt want to fire up so i didnt give it any other thought cause that one was still working when it was taken off. and if it was shorting i'd figure there would be a missfire or other condition before the problem happened. with that new module though my mileage went up a little and acceleration as well...