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Discussion Starter #1
Greetings,

I just got a 85 mk2 that had been sitting for over 2 years. The owner said the car was having problems before with loosing power and then it just stopped working altogether. It would not start - it only clicked. I got the car to start and run with some starting fluid and a boost. The car was idling very low, but ran for a while. When I removed the jumper cables, it cut off. Does this sound like electrical? Fuel? Any assistance will be appreciated.


Shawn
 

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Does the car have a good battery in it?
 

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Sounds like alternator/Wiring/fusible link from the alternator. You can technically run with only the alternator attached with no battery. This is bad on the alternator though.
Weak running while on the jumpers could be a ground somewhere. Does the other vehicle sound like it is getting bogged down or the rpm drop until you disconnect the jumpers?
Not fuel since it runs and you are saying it only stops when the jumper cables are disconnected.

There is an 85 TSRM link in my signature that has a wiring diagram.
 

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Test battery...IF its been sitting for at least that long I would just replace the battery...

Check fusible links at the positive cable end at the battery

Test alternator...

Then Check for proper voltage at battery
 
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Might be my misconception on the subject but:
If the car stops running once the jumper cables are removed then it would be that there is no power to the terminals, this is obvious. Battery obviously but since there is still no power with the engine running the alternator is also not supplying power to the battery. If you get a new battery and don't solve the issue with getting power from the alternator it will kill the battery.
In the past I have jumped a car with no battery and drove it to move around.
 

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Discussion Starter #7
It seems that my problem is complex. I tested my battery and alternator. My battery tested at around 12.50. However, I can only start the car with a jump from my other car. Even though the battery was charged and is showing good power, it won't start the car. As soon as I jump it from another car, it starts right up. When I remove the jumper cables, it cuts right off. I tried to test the alternator, but I don't know which one was showing the charge - was it the one from my car or the host car that I used to jump the car. How can you test an alternator if the car won't start on its own? The previous owner says he changed about 6 alternators as whatever the wiring problem is kept killing them. He said the alternator lasted a little while and the car drove normal until it didn't work anymore. Any ideas how I can get this issue resolved? I am prepared to take it to professionals, but who might be good at fixing these kind of issues? Thanks.

Shawn
 

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How old is the battery? Could show good voltage but have high internal resistance which would cause it to not be able to put out enough current to start the car. Recommend getting it tested at an autoparts store.
A bad battery that requires high current to charge causes problems with our cars to the point of fire. Could be that the battery or battery connection is bad and causing charging issues that burns out the alternator. Use the wiring diagram from the TSRM and do some continuity/resistance testing.
Low current to the starter plunger may be another issue. Use a starter trigger. It's a hand held momentary switch that you hook directly from the battery (+) to the starter pin on the starter. Basically hot wire it.
On my 2J install I needed to put in an additional relay to make the current to the plunger come directly from the battery. If the hot wiring method works you may need to add one as well.
If the starter trigger doesn't work and the battery is good I am at a loss and will have to differ to someone else.
 

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Discussion Starter #9
Darrow,

Thanks for your very helpful suggestions. I have removed the alternator and taken to the autozone to be tested - it failed. I have ordered a new alternator and will also get a new battery. The current battery is not the right size for the car. In fact, it's quite big and barely fits. I'm just worried that once I put in the new alternator that the real problem will destroy the new alternator. How can I determine if there are other problems?

Shawn
 

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If there's other problems, you probably won't see the proper 14.4v you should see out of a new alternator when you put a volt meter on it when running. Could be the PO kept throwing new alts at it when the battery was bad, or that he kept using crappy Alts. What brand did you get? I bought a brand new Bosche last time and its been really good.

Either way, check all your important connections, for corrosion or frayed wires or broken connectors. Like battery negative terminal, start high power lead, engine ground at the firewall, high power lead at the alt, etc. Take a good look at the main fusable link off the positive terminal and open up the black box to see if the links inside are happy.
 

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Discussion Starter #11
SupraFiend,

Thanks for the advice. Someone suggested that I put a fuse between alternator and battery to protect battery if there is a bigger problem somewhere. What do you think about this idea?

Shawn
 

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There is the stock fusible link between the alternator and the battery. That is a slow blow wire/fuse. It's the 's' shaped thing in the diagram. Modern cars have slow blow fuses but look like big fuses but with a small block inside instead of the normal looking metal bend. In the past I got a fuse block off of a '90s toyota that had a alternator fuse that connects to the battery connection and just moved the alternator wire to this newer fuse block with a newer style slow blow fuse. It is advisable since the stock fuse box will not catch fire on any type of charging/bad battery issues.
 

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Discussion Starter #13
Greetings,

I had a mechanic come look at the car yesterday. He discovered that the alternator tensioner was missing and the belt was loose. He's convinced that this is the problem as the belt is probably slipping and the alternator not charging the battery. This makes sense as the previous owner reported symptoms (car loosing power, electronics working sporadically) consistent with this type of issue. What are your thoughts? I order the tensioner but it will take a week to arrive.
 

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How is the heck is the alternator mounted then. The tensioner is the upper part of the mount. Like the top part of the alternator goes into a slot in the tensioner. No tensioner the alternator is just floating sitting on the lower mount.
It still wouldn't completely explain not running when disconnected. It should still run on battery for a bit before it loses charge. Something is still amiss.
Based on that revelation pictures may be needed of the battery to validate it is attached to the cars electrical.
 

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Discussion Starter #15
I changed the battery and now the car will start on its own. However, the multi meter indicated that the alternator was not charging the batter. The mechanic noticed that the belt was loose and went to tighten it, but there was no tensioner. The alternator was attached to the mount that the tensioner should be attached to.
 

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You've got other problems if the car is being driven like that since the same belt drives the water pump.
 

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The alternator is tensioned by a nut on a threaded rod right off the top bolt hole for the alt. I bet you the little washer that goes on the stud that goes in the top of the alternator is just not in the washer. I've seen that before where people didn't understand how the tensioner worked and were using pry bars and shit to tension up the alternator while tightenging it down. Its supposed to look like this...

 

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If your assembly isn't set up so you can wrench on this nut when the top stud/bolt is a little loose (you have to loosen the lower one too), then its put together wrong. Seen that a couple times.
 

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Discussion Starter #19
SupraFiend,

I don't even have a tensioner. The alternator is bolted straight to the bracket that the tensioner is supposed to be connected to. We only discovered this when it was discovered that the belt was loose. Went to tighten it up and noticed that there was no way to tighten.
 
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