Return of the charging/starting issue to my 91 loyale

[errantalmond]

Hi all,

tonight my trusty subie died on me while I was driving. I did some troubleshooting while I waited for a ride, and made a little bit of progress. 
I need to get my big boy running again this weekend, and I hope you all might have the advice I need.

here‘s the deal: 

I’ve had this elusive issue for some time now, where some mornings, there is no crank, just click. Sticking a little battery charger on it for 5 seconds is enough to get it going. Eventually it happened more often, and then the car wouldn’t keep itself running. (Battery wasn’t charging at all while running) I tinkered around and ended up fixing the problem with a new alternator, and then I upgraded to the Nissan Maxima alternator. Both new alternators worked great. After a few months the problem crept back in and this time, I installed one of those Bosch starter relays from Amazon. That worked a charm and has kept me Problem free ever since. Today, while running errands, I had an unusual slow crank at the gas station, then 10 blocks down, accelerating from a stop light, everything got dim and the engine had no power. It wavered for a few seconds, then died quietly and I rolled into a parking spot. No crank, dim lights. Turns out that the fuse that comes with the relay had blown. Seemed strange that it was affecting the car while it was running. I replaced the fuse and that one blew right away too, still no crank. 
i get relays in theory, but they confuse the crap out of me in practice. I definitely installed everything in the right place, and I‘m not sure how to troubleshoot it.

so I disconnected it completely and reconnected the wires the way they were before I added the relay. After getting a quick jump, the engine started up easy on the first crank, idled up for about a minute, and then everything went dim and died again as soon as I turned the headlights on.

i managed to check the voltage while it was running, 12.1 v. makes me think I haven’t solved the root issue (bad ground or something?) and that it is messing up my alternator?

called it a Night and will go back tomorrow with a charged battery to try and troubleshoot the charging system some more.

 

i really need to get back on the road for my weekly commute to Seattle from Olympia, and to get my baby off the street - please throw your suggestions my way, and come out to help if you want a bit of cash and are in the Olympia area

 

best

jon

[1 Lucky Texan]

when the car is acting normally, and you turn the ignition on, and the instrument lights get 'tested', does the batt light com on? I think if it ever burns-out, you won't get field current to the alternator.

[errantalmond]

36 minutes ago, 1 Lucky Texan said:

when the car is acting normally, and you turn the ignition on, and the instrument lights get 'tested', does the batt light com on? I think if it ever burns-out, you won't get field current to the alternator.

I believe it does come on. I will have to check when I get there today. If that was the issue, the would just never charge up, right? 
 

i don’t totally get what that means by the way, since the alternator generates a current in the first place. Is the field current you refer to responsible for giving the alternator some initial power?

Thanks!

[1 Lucky Texan]

not all, but many, cars are made this way - others can give more details I'm sure;

http://www.pirate4x4.com/tech/billavista/Wiring/Part2/images/Alternator-block_diagram-2.jpg

 

 

Edited February 28, 2022 by 1 Lucky Texan

[Ionstorm66]

Check the voltage between the alternator output and the positive battery terminal. It should be 0. If there is any voltage you have an issue between the alternator and the battery. Likely the fusable links are old and corroded.

 

Also while the engine is running, check voltage from the case of the alternator to the ground on the battery, this should be 0 too. If there is any voltage then you have a bad ground.

 

Next check to see if the 2 pin connector at the alternator has 12v at the bigger wire with the engine running.