74 Spider, green smoke escapes, cause unknown (starting issu

[perthling]

Let me set the scene.

My trusty '74 spider has been on stands for a couple of months while I overhaul the front suspension, fit sport srings, new master cylinder, hoses, pads and rotors.

Drop her back onto her wheels, connect battery, turn on ignition for fuel pump to circulate fuel. (Can hear it ticking). After 20-30 seconds, crank her over and she coughs then starts up. Runs for a few seconds then sputters out (cold, no choke etc - not unexpected). Start her up again, runs for a few seconds then quits. Different kind of stopping - not a fuel/air type issue, but electrical in that it doesn't even cough, just stops.

Turn the key off and on, start poking around for a reason why she has stopped. A few seconds later a mass of electrical smoke billows from behind the dash. I pull the battery isolator and start probing behind the dash. The blue-with-black-stripe wire which leads from the fusebox to the ignition coil is red hot, it has melted the sheath and looks like it has shorted out some of the other wiring as it has melted.

So, I can fix the symptom but am trying to work out the cause. Is it possible that the ignition coil can have failed in a way that resulted in a short being generated? Ignition coil had been replaced from standard points type to higher power type (Bosch) to support electronic ignition, but car has been run for 18 months with this system fitted without problem. Not sure why the fuse didn't pop either, as that should have been the weak link.

Will be reviewing the fuse installation and wiring diagrams in the coming weekends to determine the extent of damage and possible causes/factors.

Anyone else ever experienced anything like this? If it's not the coil which caused it, could it be a fault in the ignition barrel instead? Would/could that lead to a short back through the ignition wire?

As electrical is not my forte, any help would be greatly appreciated.

[124JOE]

you poor guy
hello perthling,
sorry to hear anyone to ever have this type of issue.
i had a problem simalar to yours,

it only takes one time to turn it over and pow a huge disaster.
so this is how i remember,
turned it over and burned a wire up from the ING to the coil.zap!
bad smells and all.
i got some heavy wire "i think 16 gauge"and ran a replacement
remove the old one at least what you see.
then start on the others one at a time.
just try to stay with the same gauge"as you see/replace" rule.

joe

[perthling]

Joe

Did you determine what caused your problem though? I also thought about running thicker gauge wire, but as the car ran fine for 18 months with the current setup I feel that's just a bandaid solution rather than tracking down the root of the issue.

Glad to hear I'm not the only one though!

I have a complete loom from a Coupe so a can potentially replace large sections without too much effort (apart from the dash removal etc).

[124JOE]

yes it had a meyal braket to hlod the wires on the inside fender that had lost its screw
so it slid down to the coil and arked!
i found it right away and only lost the one wire

once you reroute al the bad wires it might be fixed.

good luck.joe

[perthling]

Just an update on this, the issue was traced to the ignition barrel. I replaced the more modern coil I had fitted previously with a barrel type coil (I suspected the modern coil may have been fired during the incident), ran a fresh wire between the ignition and the coil (with a fuse installed) and also overhauled the ignition barrel (disassembled and cleaned terminals).

This has fixed the problem but I will also be installing headlight relays to take some of the load out of the ignition switch.

[KidDingo]

G'day Perthling,

I did the headlight relay upgrade using the IAP kit. Modified it a bit so as not to disturb the original wiring too much, just in case I had to go back and retrofit the old set up. It works great, although I don't have any dashlights now, but that might be unrelated.