Strange Ignition Problem

[jimynick]

How about putting a meter across the + side of the coil and watching the voltage as the car does it's act. If you're losing voltage either partially or completely, then at least you can trace the problem with the feed. As stated, HEI wants a straight 12 volts all the time and that's the first thing I'd confirm. 

[Super Blue 72]

Is there a way to test those GM modules?  Might not be the module...   

[HEMROID]

I wired up the amp gauge wires as a quick check yesterday, it seemed to work...

So having read this article (really informative) I've gone and done this exactly as this - save for bulkhead connectors as they were new in my car - so it has obviously had this problem before:
http://madelectrical.com/electricaltech/amp-gauges2.shtml

I used 12 gauge wire but I didn't use the soldier connections... Hopefully it'll be ok.

Even if this isn't my problem it should be done anyway, I'll replace my Ammeter with a Volt meter.

[HEMROID]

And it won't start again, no ignition. Going to hook it back up excluding the Ammeter and see if I can get ignition.

This is so frustrating.

[HEMROID]

No ignition, probably another dead module? Since I've paid for five so far, at various shops who have no idea what the problem is, I'm not buying another one. I've nearly bought the MSD's value in modules.

Going to leave it again today.

[Super Blue 72]

 

Get some rest and start fresh in the morning... 

[Super Blue 72]

Ooops, just saw you are in Australia.  I have nooooo idea what time it is ober there!!!    It's 10:48pm on the east coast of the USA.

[HEMROID]

Haha you're right though, it's 99 degrees here today so I'm going to leave it. Have had enough. I'm seriously tempted to fit the MSD.

[Talkwrench]

Correct coil should be Bosch HEC 716  [715 if you want female connection]  0.41 Ohms
I converted to HEI using a cheap chinese dissy and then used good bosch parts, module and coil. Re-graphed it myself and I havent had problem, goes real well.
Note what has been said about No ballast resistor and it getting full 12 volts...

[HEMROID]

I just took the cover off the module, checked the earth and all the wires and now it fires but doesn't run! Ignition dies instantly.

I definitely don't have a HEC716 - it looks nothing like it. It's some other piece of junk that just says "12V performance coil".

[jimynick]

With the latest piece of the puzzle being it fires but won't run, have you considered the ignition switch? There are two separate positions- start and run and if the one works, maybe it's the other. If you read my first post, you'll put that meter on the coil and see when and on what circuit you've got/lost voltage. Infuriating, no doubt.

[HEMROID]

The voltage at the coil is fine and I think the ignition switch is fine too, but all I've done is fiddled with it ie. holding it in certain positions and whatever else. I tried all that very early on as it's what I thought it was.

Seems the coil that I have needs the ballast resistor in place (which was unhooked when I got my tune - I removed it). It needs 1.5 ohms of resistance. But I don't know what symptoms and overheating coil would show? It would be more than just no spark at all I'd presume? Which it is, sometimes. But then again, it really is anything in between (spark for 5-10mins, starts but won't run, no spark at all).

Either way I need a new coil, I'll get one tomorrow.

[Super Blue 72]

Just a thought, if it doesn't take too much work, might be an idea to consider changing it back to the old ignition set up and see if it runs to rule out other possible issues, like jimmynick just mentioned maybe it's a ignition switch or other part outside of the parts in the new ignition system. 

[HEMROID]

Fitted the HEC716. For Australians with HEI, the replacement Repco part (they no longer stock the genuine Bosch item) is a barrel type and incorrect.

The car seems to want to start today, but it just won't run. I had it run for about 10 seconds but it was farting around like it and not wanting run. I do wonder if it's killed another module...

I really need someone who knows what they're doing to look at it. Sigh...

[HEMROID]

Just advanced the timing and it runs! Strange because I never touched the distributor, seems the old barrel coil with no ballast was the problem. The car won't idle now, though. And I of course there's no timing mark on the car and the blokes who tuned the carby said the engine was too tight to turn to put one on.