Ignition problems

[Daveje]

OK, I have an '85 that starts for instantly, runs smoothly, and then dies 2 seconds later.I hadn't started it for about a week while I was working on the interior. Went to start and there was no spark at all from the coil. I had put in a new pick-up about 2 weeks ago(it was runnig fine after that) so that's the first thing I thought. Changed it out with the old one and now it has spark but runs for 2 seconds and dies.Put the new one back in to confirm and no spark, so I'm back to the old.2 bad pick-ups? Kinda funny. There is 12v to the coil. Coil resistance seems low to me, .5 ohm primary, 5800 ohm secondary, this is with some sort of short can coil and ignition module like they sell at IAP. Spark jumps a good gap with the old pick-up but is whitish-orange. I'm thinking it's an ignition problem because of the initial no spark although seems to be spark now. Fuel pump comes on with the AFM door just fine. Anyone have any ideas of what to check next? Is there a way to check the ignition module?

[rlux4]

Have you checked that your injectors are pulsing? The cold start valve will run the engine for a few seconds, but without the injectors it won't continue to run.
Ron

[Daveje]

Thanks Ron.That's makes sense and that was next but it's kind of odd there would be no spark and as soon as that's cured no pulse to the injectors but I will check that tonight.Stranger things have happened.

[rlux4]

But it sounds like you have spark if it shows at the plug and the car will run for a couple of seconds.
Ron

[Daveje]

Yep, what you're saying makes perfect sense so I'll look at that tonight. i just can't make sense of the initial no spark/pick-up thing so I've been stuck on that. Anyone know what correct resistance on that coil should be? I'm wondering if my spark is weak or something also since it's not blue which is what I thought you're supposed to look for. Blue spark good, white-orange weak.

[Daveje]

Problem is solved. Thanks again Ron. Couldn't find a pulse at the injectors, so I went through one of the troubleshooting guides and found there was no power on the ECU pin 1, which is power from the coil. The wire was loose in the crimp connection at the coil. Fixed it up and the car runs as good as usual. I guess the ECU won't fire the injectors if it doesn't sense power from the coil? Makes sense, no need for fuel in the cylinders if it thinks it's not firing.Anyway,I'm happy,easy fix, and I love a repair that doesn't cost a dime. Now I just need to retest the new pickup and see if it's really bad, doubt it.

[rlux4]

Great! Thanks for letting us know how it came out.
As an aside; I was diagnosing a poor idling problem and got zeroed in on the coolant T temp sensor ( I have a new one on the way from Autoricambi) and when I plugged the connector back on I forgot to pop the clip back on. Later on the way up to Mojave to pick up my daughter (105° in the Mojave desert) the car died on the freeway. As I pulled over and coasted to a stop I checked the tach, which still showed RPMs, so I knew it wasn't ignition related. Before I even popped the hood I knew I'd find the connector had come off the sensor. I was right. Plugged it back on, put the clip in place, and it fired right back up.
The worst part of it was how bad I felt knowing the people passing me were thinking that I was having problems with a Fiat. I wanted to make a sign, "It's my fault, not the car's!"
Ron

[Daveje]

Yep, this was my fault also I'm sure. Probably leaning on the connector or something when I was changing out the pickup.The car did have the courtesy to die in my garage and not on the road at least. Of course all the wife and kid know is dad's fiat is not running "AGAIN". The cars aren't perfect for sure, but all my problems with it have been age related or the "repairs" that have been done to it. They are at least as good as any other car of the era. (Oh, except for that whole rust-prone fuel tank thing )