Power Cuts

[Ellie]

Hi there, Twice in the last month I have been 20 min into a leisurely Sunday drive and the engine cuts out, as if I'd turned the ignition off. While the car has momentum i try jump starting but there's nothing. So I roll to a safe place off the road. I try starting and she turns over spritely but doesn't start. I call the Road Assist and they couldn't find anything other than there is no spark at the plugs and no power at the coil. We were about to call for a tow and I tried one last time. The car started and sat there purring like a kitten. Happy days So I drove home. Noting this was after turning the imobiliser off and on numerous times and I suspected it wasn't making the same sound as normal, clicks etc.

The second time, today, same thing happened, although I took the tow truck option this time but once off the truck, I just started her up and parked in the garage as if nothing was wrong. Its like if I let her sit for an hour (waiting for road assist), she suddenly decides "its ok, I can go now"

Question is I guess, is there anything in the power circuit that may cause loss of power like this? maybe if something gets too hot? My favorite thought at the moment is that the imobiliser is faulty, just randomly coming on and eventually deactivates allowing power through.

Any suggestions are most welcome

[bobplyler]

I had a similar problem 2 years ago. I just replaced all ignition parts (coil, wires, magnetic pickup, distributor, rotor).

Also, about 15 years ago, I had a problem where the car would die. Open the hood, let it cool down, and it would start. That time, I had a pinhole in a radiator hose. It got hot, and sent a small mist onto the coil.

[18Fiatsandcounting]

My guess is one of two issues:

1. Bad Ignition Control Module (ICM). When these go bad, they stop working when hot and the ignition system shuts down. Solution: new ICM, and these are fairly generic with GM (General Motors) offering a pretty good version that works well for the Fiats.

2. Failing ignition switch. Contacts within the switch go bad over time, with the result that the ignition cuts in and out. Sometimes you can diagnose this by grabbing hold of the wires coming out of the back of the ignition switch. As you gently move them around, the ignition will cut in and out. Sometimes it's just the wire connection to the back of the switch, but more often the problem is internal in the switch. Solution: A new ignition switch.

-Bryan

[Ellie]

Hey thanks for those tips, its always a bit of a mystery when something is intermittent but its becoming a regular event so I'll need to explore and do something and those are good places to start.

Cheers

[spider2081]

Trusting the idea there was no voltage at the ignition coil, I would do some tests at the ignition switch's connector. I would first check for voltage on both the black and the brown wires at the ignition switch connector. Both of these wires feed battery power to the ignition switch. With the key off there should be battery voltage on both wires on both sides of the connector. Then turn the key on and the voltage should remain close to the same again on both sides of the connector. I would then separate the connectors and inspect them for overheating. Overheating is evident by the connector shells turning brown from their original whitish color.
Sometimes an indication of an ignition switch/connection issue is seen by the warning lights in the tachometer (oil pressure and battery warning light) not lighting when the ignition switch is turned from "off" to "run" position.

Hope this is a little help

[Razooli]

Had the same problem ... ignition switch swap did the trick.

[Ellie]

Fun turn of events, car wont start at all now. Will give me something to work with rather than being intermittent. There's no spark at the plugs, 12.6V at the coil but the Coil resistance checks were reading .7 between the terminals and 7.6k OHMS at the high voltage terminal which seems low compared to the 10 to 11k spec in the manual. Does this suggest a faulty coil?

[spider2081]

between the terminals and 7.6k OHMS at the high voltage

Yes that is low. Do you have all the wires removed form the coil when performing the resistance test? It is more common for the Ignition Control module to fail then it is for the coil to fail. Also have you removed the distributor cap and inspected the the pick up coils wires?
You should have battery voltage at the coil in both the "start" and "run" positions of the ignition switch.

[Ellie]

Is there any way of testing the ICM? I may just put a new one in as I think they're relatively cheap. i tested the Coil while in the car connected and then on the bench by itself for the resistance checks, same readings though. Strangely I would normally have started at the distributor but haven't this time, thanks for the reminder

[Ellie]

Just to close this one off, I put in a new module and left everything else. Started first time Went for a drive around the neighbourhood and all was good with the world.

[spider2081]

great news, enjoy your ride