Engine shuts off randomly

[jeffshaw57]

Greetings Fiat lovers,
My 1980 carbed Spider has got me stumped, so I'm asking for your help. I've been driving this car for 34 years and know it pretty well:) It starts easily and runs like a top. A few months ago it randomly shut off while driving it on an in-town trip. I assumed it was the pickup coil wire broken which happens every decade or so. I coasted into a parking lot, popped off the cap and rotor, and checked the leads. They looked good but about time to replace so I wiggled them, replaced the rotor and cap (I've converted to electronic ignition), and turned the key and off I went 5 minutes later. I ordered a new pickup coil and replaced it and it wouldn't start at all! I put the old one back on and it started first turn. I ordered a second one and replaced it. Same thing, it wouldn't start, so I put the old one back on and back like new.

Not exactly. The random shut off after a short trip still happens. I can wiggle wires, check everything (or do nothing) and a few minutes later it starts and I make it home. I decided to replace my ignition module and coil with high performance ones just to eliminate things. Original problem remains and I added a problem. Now I cant turn over 2000 rpm without the engine stalling. I replaced the plugs with the new RGK iridium ones gapped at .035. No change. Still stalls when trying to rev over 2000 rpm (driveway or road). I put the old working coil back in and runs perfectly. It's not temperature related either. I can jump the fan constantly on and keep the temp to under 120 and it does the same thing.

It doesn't matter if the car is sitting motionless in the garage running or rolling down the road, it will shut off randomly. For example, just now it idled for 20 minutes and then shut off. I turned the key off, waited and 3 minutes later it started up and ran for 30 minutes before doing it again with a 20 minute idle and a 10 minute drive in the neighborhood. Now it has been nearly an hour and it will not start again (I pushed it home). The car did the identical thing 2 weeks ago and I had to tow it home (It started right up a few hours after that).

I have good fuel pressure, good return vent line, and have tried the gas cap off trick with no change. The fuel shutoff solenoid is working as I can disconnect the 12v lead and hear the click. When it won't start, I can pull the green lead and hear the solenoid click. The only way to explain what this shut off feels like would be to pull the fuel solenoid lead. The engine shuts off exactly like that. No spitting or stuttering, just off.

Any thoughts on what this is causing the shut off? I'd also like to know what the deal is with the new pickup coil replacements not working at all. One is the low cost one (with the black cable) and one is expensive (with the white cable). Also, I bought them from two completely different suppliers to eliminate a "bad batch". Thanks in advance!!!

https://imgur.com/a/XHHlZ

https://imgur.com/XHHlZ

[redcars]

This sounds a lot like a bad ignition switch. See if wiggling the ignition switch makes a difference.

[wetminkey]

That's what I'm reading in your post,...
Hope this helps!
Todd.

[RRoller123]

When it won't restart, check for spark at the plug while cranking the engine. A timing light over the spark lead will give a visual indicator.

[DieselSpider]

You may want to check for low voltage at the coil or distributor. On mine I had a problem where hitting the brakes caused the engine to stall and it was simply the extra load on the circuit causing a voltage drop below what was required to keep the fuel valve open on the Diesel. I had to trace back the power feeding the brake lights and fuel valve to find the connection that needed attention. I had originally thought I had a short from a broken wire or bulb however that was not the case.

[jeffshaw57]

Redcars & wetminkey- I replaced the ignition switch a couple years ago when I discovered that high resistance had burned one of the contacts and wire at the switch. While I won't 100% rule it out, I doubt it is the cause. Especially since it does the same thing idle or driving at about the same run time. It spins over and doesn't start (just like the carb fuel solenoid).

Rroller123 - I'll pull a plug wire and look at the spark to ground when it's not running and see what it's doing.

Dieselspider - I doubt it's voltage related as the lights all stay the same and I have a new alternator and battery. I will check the cranking voltage when it has quit and won't restart!

Guys - great suggestions! I will test and report back and let you know what I find.

Jeff

[spider2081]

It spins over and doesn't start (just like the carb fuel solenoid)

I doubt it's voltage related as the lights all stay the same and I have a new alternator and battery

Did you replace the original Sipea ignition switch with a Sipea switch or did you purchase a Lada ignition switch and rewire your car to accommodate the difference. The Sipea switches use 2 sets of contacts for the "run" position of the key and the Lada use only 1. Hence they do not last as long as the original.

The original Sipea ignition switch has 3 internal set of contacts. The brown wire brings power to 2 sets of contacts. One powers the headlights in the "start and run" positions of the ignition switch. The other powers the starter solenoid when the ignition switch is in the "start" position. The 3rd set of contacts is powered by the black wire. it powers the ignition system and items on fuse 1 when the ignition switch is in the "start or Run positions. So it's possible for your lights to work fine and the car to crank fine and not have proper voltage for the ignition system. When the car cranks and does not start do you have battery voltage on the pink wire of the ignition coil??

[jeffshaw57]

Spider2081 - Last night I decided to crank it up and idle until it shut off to test voltage at the pink wire on the coil. It ran 22 minutes and prior to shut off voltage was 13.5 (pink to ground). Note- pink to black on the coil is 1 volt. Immediately after shut off the volts pink to ground were 12 and, with fan running. It held but slowly dropped to 11.5.

It started right up 2 minutes later (like it has been doing) and I let it idle for another 90 minutes without any shut off! If I had tried anything new or swapped a part I would think I had solved the problem but I hadn’t. This is the first time in months it’s not shut off in 30 minutes or less after running. Does this give anybody any more clues??? Thanks,

[spider2081]

I think your voltage reading of 13.5 volts with the car running is a good measurement as the alternator brings the battery voltage up a little. When the engine died you voltage reading is still good because the alternator now is off line and you are measuring battery voltage. So I think this appears to eliminates a lot of the connections between the battery and the coil including the ignition switch.
I'm wondering if temperature is part of your issue and now the component related to your issue is not getting as hot as it did before. This past summer a number of my friends had intermittent issues and felt the Ignition control modules were the problem. One problem occurred after the module was replaced as preventative maintenance. Another felt it was the ignition pick up module failing when hot.

[DieselSpider]

Cooler weather can really mess up trouble shooting some of these potentially heat related issues. Even trouble shooting with the hood open and add a wrinkle to the process. I had similar on a motorcycle that by the time I got the panel off to check things every thing had cooled off enough to return good readings on the meter even though there was a faulty component. It wasn't until it failed 100% that it apparent where the failure was.

On my car all the voltage readings were good however the problem with stalling went away when I connected the brake lights to a different feed circuit in the fuse box which I believe was the courtesy light. The relay that keeps the fuel valve on the diesel open only draws a few milli-amps and draws power for the load directly off the battery cable. I have not been able to find the original fault with the circuit that originally powered the brake lights either however it run reliably for about 2 years now using the other power feed for the brake lights.

[jeffshaw57]

I think your voltage reading of 13.5 volts with the car running is a good measurement as the alternator brings the battery voltage up a little. When the engine died you voltage reading is still good because the alternator now is off line and you are measuring battery voltage. So I think this appears to eliminates a lot of the connections between the battery and the coil including the ignition switch.
I'm wondering if temperature is part of your issue and now the component related to your issue is not getting as hot as it did before. This past summer a number of my friends had intermittent issues and felt the Ignition control modules were the problem. One problem occurred after the module was replaced as preventative maintenance. Another felt it was the ignition pick up module failing when hot.

spider2081 I don't think it is ignition module as I was having the problem before and replaced it with a better one 2 weeks ago and the car shuts off ablot the same run time. I would like to eliminate the pickup coil but neither replacement allows the car to start. Read my original post. What the heck here!

[jeffshaw57]

Cooler weather can really mess up trouble shooting some of these potentially heat related issues. Even trouble shooting with the hood open and add a wrinkle to the process. I had similar on a motorcycle that by the time I got the panel off to check things every thing had cooled off enough to return good readings on the meter even though there was a faulty component. It wasn't until it failed 100% that it apparent where the failure was.

On my car all the voltage readings were good however the problem with stalling went away when I connected the brake lights to a different feed circuit in the fuse box which I believe was the courtesy light. The relay that keeps the fuel valve on the diesel open only draws a few milli-amps and draws power for the load directly off the battery cable. I have not been able to find the original fault with the circuit that originally powered the brake lights either however it run reliably for about 2 years now using the other power feed for the brake lights.

DieselSpider I have done my best to eliminate temperature from the equation by running it without a fan up to red without shut off, tried it on cold and hot days, and jumped the fan on so it couldn't get over 120. All the same random shut off!

[spider2081]

I would like to eliminate the pickup coil but neither replacement allows the car to start.

I recently helped a friend whose Spider would not start. I unplugged his pick=up from the coil pack to measure the pick-up resistance. The blue wire (small pin) in the connector had pushed back in the connector and was not mating with the ignition module. I tried to hold the wire as I plugged it in but could not keep it from moving in the molded black connector. I finally put the connector in place then used a pair of needle nose pliers to push the blue wire into its housing. Once I did this the car started.

You might look into the pick-up connectors and see if the spade connectors are all the way inserted. If they are you might measure the pick-up resistance it should be about 750 ohms. Lastly I have seen the magnet strip on the to and the bottom of the magnet. The magnet is properly installed when its outline shape coincides with the pick-ups base plate shape.

[bobplyler]

If it won't start, I would try spraying some starter fluid in the carb. If it starts, it's a fuel problem. If it doesn't, it's probably ignition.

[jeffshaw57]

I would like to eliminate the pickup coil but neither replacement allows the car to start.

I recently helped a friend whose Spider would not start. I unplugged his pick=up from the coil pack to measure the pick-up resistance. The blue wire (small pin) in the connector had pushed back in the connector and was not mating with the ignition module. I tried to hold the wire as I plugged it in but could not keep it from moving in the molded black connector. I finally put the connector in place then used a pair of needle nose pliers to push the blue wire into its housing. Once I did this the car started.

You might look into the pick-up connectors and see if the spade connectors are all the way inserted. If they are you might measure the pick-up resistance it should be about 750 ohms. Lastly I have seen the magnet strip on the to and the bottom of the magnet. The magnet is properly installed when its outline shape coincides with the pick-ups base plate shape.

Spider2081 - Interesting! When I ordered a new pickup coil (the first thing I tried to solve this problem), the new one came in with the blue connector pushed in so far it wouldn't make contact. I told the supplier and he sent a replacement which did not have a pushed in connector. I checked my original, which I'm still using, and it is not pushed in. What I can't figure out is why the two replacement pickup coils dont allow my engine to start. Should I check the magnet? I really don't see anything out of the ordinary.