Is this a symptom of a weak alternator?

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My FJ40 was fully restored and when I got it back it ran fine for two days and then things started going wrong.

I first started noticed it when I hit around 100km/h on the freeway and the car made a popping sound and the engine felt like it had hit the rev limiter.

Then it started happening at lower speeds, 80km, then 60km, eventually, it would keep stalling to the point I couldn't keep the car running for a minute.

I sent the car back to the garage and they attributed the problem to a faulty distributor. On Thursday I picked up the car and they told me they were waiting on a new alternator to arrive since the one I had wasn't strong enough but that I could drive the car temporarily. So I took the car and drove it to my hotel around 30 minutes away (the car is in a different country so I was staying in a hotel). As I was parking I noticed my AC was making a weird ticking sound, but if I pressed the gas pedal in and revved the engine RPM up, the sound with go away. I took note of it then parked the car and checked in before deciding to go grab a bite to eat.

When I went to start the car the battery was completely dead. Luckily hotel valet had a booster so boosted the car and I decided to take the car back to the garage. On the way back, maybe 15 mins from the garage, I turn on the lights cuz it was starting to get dark and then a few minutes later at around 100km/h the car makes a popping sound, I was like oh s***. So I move over to the far right lane and slow down, the car started to choke and eventually died. So I rolled off using momentum to the side of the road.

Obviously, I was really upset since the garage had assured me the issue was sorted when in fact it wasn't. They're now saying the issue is happening because of the weak alternator, which I guess could make sense? Does that sound right? Could it be the alternator? I sadly don't trust anything the garage says anymore.

stuck1.jpg


stuck2.jpg
 
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The alternator is not working well. When the truck was boosted you had the charge in the battery which didn’t last long.

It’s likely the alternator or the regulator. However, it could also be poor connections between the alternator and battery (but less likely).

With a functional alternator it’ll keep running with little to no battery. When I’d had my 40 parked for 2 years the 7 year old battery was complete dead. I jumped it and drove home 90 miles. It wouldn’t restart without a jump, but would run all day once started.
 

Subterranean Nik

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Can the garage check for you with a multimeter?

With truck running (after getting base voltage measurement as well), should be able to take a voltage reading at battery posts and determine if alternator is charging.

Agree with @bikersmurf as to likely issue.

Good luck and beautiful restoration!!!! Hopefully this is the last hurdle for you.

Nik
 
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Noting that it is “fully restored”, makes me think some of the ground connections may be poor due to paint. You may need lock washers that’ll bite through it the paint to make a good connection.

In a full restoration I’d likely rebuild or replace the alternator… but definitions vary.

Don’t get discouraged… they’ll likely be a few things to sort out and then you’ll have a super reliable truck.
 
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But are the symptoms related to a bad alternator? I know battery dying is a symptom but the engine making popping sounds out of the exhaust (like a backfire) then stuttering and dying while cruising on the highway, is that something a bad alternator could cause?
 
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But are the symptoms related to a bad alternator? I know battery dying is a symptom but the engine making popping sounds out of the exhaust (like a backfire) then stuttering and dying while cruising on the highway, is that something a bad alternator could cause?
Backfiring is not an alternator issue, it is an ignition issue or could be the mixture is too lean. You said they replaced the distributor but did they install new cap and rotor with new wires? It could be a crack distributor or carbon tracking in the distributor also ask to check the base timing. Hope it's a simple fix.
 
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Backfiring is not an alternator issue, it is an ignition issue or could be the mixture is too lean. You said they replaced the distributor but did they install new cap and rotor with new wires? It could be a crack distributor or carbon tracking in the distributor also ask to check the base timing. Hope it's a simple fix.
thanks, noted these points down for when i talk to them next. its the only issue left on the car I want to get sorted so I could finally enjoy the car. the 30 minutes I had with he car this weekend was a blast.
 
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there isn't a coil installed i think, well it's not the cylinder coil at least. they installed this for me:

View attachment 3160202
Not familiar with your particular vehicle, is that coil factory? Looking at the wire connection could be also poor connection.
 
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Not familiar with your particular vehicle, is that coil factory? Looking at the wire connection could be also poor connection.
no, not factory, i actually hadn't seen a coil like this except in my vehicle, not even sure how to search for it online since ignition coils brings up the regular cylindrical ones.
 
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no, not factory, i actually hadn't seen a coil like this except in my vehicle, not even sure how to search for it online since ignition coils brings up the regular cylindrical ones.
The coil could be your issue also the wires seem too small for a coil and it needs to be solder in all terminals and sealed.
 

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