1979 Spider won't crank

[Pescado]

Hey all,

Hope everyone has been enjoying the top down weather....Soooo yesterday decided to go out with my daughter for a "rip" and when I turned the key cranking was very slow and then stopped cranking, turned the key again no cranking. Tested battery and coil all looks good there, tested ignition control wire... looks good. Haven't tested the starter yet as it look like a PITA to get to so not enough time to dive into that...going to search up some starter testing videos later to see what I can figure out.

some extra info....a few days ago I was going to try the "brown wire fix" and while under the car I was looking to see how I could fit a wrench on the starter bolt and accidently made a spark show....of course I should of disconnected the battery (rookie mistake). I did start the car after this incident and drove around a few hours with no issues...but thought I'd mention this in case I damaged the starter...thoughts?

[18Fiatsandcounting]

Despite your attempt at arc welding, I don't think you damaged the starter.

If the engine turns over slowly but then stops, it's usually one of four things:
1. Dead battery. A old battery can read fine with a voltmeter, but when you try to draw any significant current out of it, the battery voltage drops way low. You can test this by measuring the voltage at the battery posts when someone else is turning the key to start. If you get less than 8 or 9 volts, your battery is bad. 9 to 10 volts is marginal.
2. Bad battery cable connections. This includes not only the connections at the battery posts but also the ground connection to the body and the plus connection to the solenoid on the starter motor.
3. The solenoid on the starter motor is going bad, in terms of the copper contacts inside are not working right. This is hard to test, so I'd eliminate the above two possibilities first.
4. It's really, really cold where you are, like below zero Fahrenheit. I kinda doubt this is the case!

-Bryan

[Pescado]

Despite your attempt at arc welding, I don't think you damaged the starter.

If the engine turns over slowly but then stops, it's usually one of four things:
1. Dead battery. A old battery can read fine with a voltmeter, but when you try to draw any significant current out of it, the battery voltage drops way low. You can test this by measuring the voltage at the battery posts when someone else is turning the key to start. If you get less than 8 or 9 volts, your battery is bad. 9 to 10 volts is marginal.
2. Bad battery cable connections. This includes not only the connections at the battery posts but also the ground connection to the body and the plus connection to the solenoid on the starter motor.
3. The solenoid on the starter motor is going bad, in terms of the copper contacts inside are not working right. This is hard to test, so I'd eliminate the above two possibilities first.
4. It's really, really cold where you are, like below zero Fahrenheit. I kinda doubt this is the case!

-Bryan

I can tell you how happy I am that I posted this before going into a starter replacement....you are right battery is no good, drops to 5v when cranking. New battery in and spider is happily cruising the streets again. Thanks again for the help...CHEERS!

[Pescado]

Looks like I still have an issue…replaced the old battery from 2016 and based on its age I thought this was for sure the issue at hand but it appears something else is going on. Yesterday while driving I noticed the brake light and seat belt light came on plus stereo started cutting in and out. I pulled over on a side road and turned the car off to see what would happen after restarting and guess what….no start . Clutch pop and got the car home, put the battery on a charger which showed the battery having low capacity. Charge the battery for a few hours and brought it back to life…let the testing begin.

Battery voltage with car off 13.2
Battery voltage when starting the car drops to 12.5 and the returns to 13v
Battery voltage stays at 13v when engine rpm is increased to 2500
Battery voltage drops to 12.6 when headlights and fan is turned on high speed

The manual I’m using to troubleshoot says if voltage doesn’t drop below 12.5 the alternator is good ( not sure about this).

I’m going to try and disconnect the battery lead while car is running to see what happens but wanted to post this info ahead of time to see your thoughts. Happy Sunday all….GO GIANTS!

[18Fiatsandcounting]

I’m going to try and disconnect the battery lead while car is running to see what happens but wanted to post this info ahead of time to see your thoughts.

I strongly suggest NOT disconnecting the battery lead while the car is running. Old style alternators used to be able to handle this, but the more modern ones like in your '79 don't like it. With the battery disconnected, the alternator goes full on and often burns out the voltage regulator.

That being said, I disagree with a shop manual that says the alternator is OK if the voltage is 12.5 volts or more. A fully charged battery can be up around 12.6 even if the alternator is doing nothing. Fiat alternators generally charge between 14.3 and 14.5 volts, and so if you get less than that when the engine is revved up, you may have a bad alternator. See above paragraph.

Based on the fact the stereo cuts in and out, it sound like you have an intermittent connection for the +12V supply for the car, and the most common cause for this is the ignition switch. Power cutting out could also "reset" the Fasten Seat Belts timer, so it comes on again. Perhaps the brake light also has a similar timer.

Very common for ignition switches to do this as they age. If the car acts up again, try wiggling the connections at the back of the ignition switch and see if anything happens. You could also have a bad connection somewhere from the battery to the ignition switch, or possibly at the fuse box. This might also cause the alternator to not charge all the time, so that could be running down the battery.

-Bryan

[spider2081]

The manual I’m using to troubleshoot says if voltage doesn’t drop below 12.5 the alternator is good

I am pretty sure your alternator should be regulating the voltage between 13.8 and 14.5 volts. !3 volts is too low for a working alternator.

Measure the battery voltage at its posts (not the cable terminals) This is the reference voltage the alternator has to be more than to charge the battery. Usually an alternator output voltage ia 1-2 voltas above the battery voltage for the battery to get a good charge.

Your symptom of the battery loosing charge points to the alternator or voltage regulator not function as it should.

I think Bryan has given you some good information.

[Pescado]

sorry I was away got sick...feeling better today so i'm going to revisit this now thanks for the info/help.

[Pescado]

Voltage at battery when disconnected from the car is 13v....I think im going to pull the trigger on a new alternator ordering piece by piece with shipping and duties gets pricy. Is there a domestic substitute that people use by any chance?

[spider2081]

If the alternator has failed usually the red battery warning light stays lit. Also if you measure the voltage at the battery with the key on but engine off it should be slightly over 12 volts. Then start the engine. With the engine running over 1200 rpm the voltage should increase 1.5 -2 volts toward 13.7-14.5 volts. If the voltage remains in the area close to with the engine not running chances are the alternator is defective. I think the voltage regulator for a 1979 is mounted to the alternator. So replacing the alternator replaces the voltage regulator.
Getting involved with fitting a non stock alternator on the car involves fabricating brackets etc.

[18Fiatsandcounting]

Before going to the trouble and expense of getting a new alternator, I suggest finding a shop that will test your alternator while in the car. Some shops might do this for free, or perhaps just charge a small amount. This assumes you can drive the car to the shop.

If you do need a new alternator, you don't have to order it from the Fiat vendors in the US. Any decent Canadian auto parts store (NAPA for example) should be able to get you a new alternator. The Fiat ones are pretty standard.

-Bryan

[Pescado]

thanks for the help guys...doing some shopping now.