Diagnosing an Electrical Problem

Matthew A. · Post by **Matthew A.** » Wed May 08, 2013 7:48 pm

So it seems I can't quite shake the gremlins just yet. New alternator went in a couple days ago, and started her up and then she chugged out and died.

Today we jumped her and tried running her slaved to the other vehicle. Batter was charged up nicely, and she started. Then she chugged along for a little bit, and then died. Started her again and she died even sooner. Disconnected her from the other car and pulled the plugs. Their wet which tells me that it's not a fuel line issue and that it's in the electrical somewhere.

I've looked in the distributor so I know that's not the issue and I can rule out the alternator as she was chugging even under power from another vehicle. This points me towards the ignition system or the timing. She also chugged out and died the second I tried to give her a little more gas to try and see if we could get her running properly.

The only change I've got between this alternator and the old one is that I don't currently have the ground connected to the alternator. I'm not 100% where it should go and the only place that seems like it should go is connected to a black box which is connected to the B+ post by a wire. Some help on that would be nice, but mainly I need somewhere to go on this chugging out and dying gremlin.

Mike W. · Post by **Mike W.** » Wed May 08, 2013 10:26 pm

An 80 would have the rubber mounts which make a ground wire absolutely necessary. One of the 4 screws holding the case together should stick out half an inch or so. Hook a ground wire, at least #10 if not thicker, to the block or a metal bracket that bolts to the block. Then read your charging voltage with it running, it should be at least 13.5 and hopefully more like 14. You need a meter, even a cheap one, but you need a meter.

Matthew A. · Post by **Matthew A.** » Wed May 08, 2013 10:57 pm

Mike W. wrote:An 80 would have the rubber mounts which make a ground wire absolutely necessary. One of the 4 screws holding the case together should stick out half an inch or so. Hook a ground wire, at least #10 if not thicker, to the block or a metal bracket that bolts to the block. Then read your charging voltage with it running, it should be at least 13.5 and hopefully more like 14. You need a meter, even a cheap one, but you need a meter.

She comes stock with a ground wire bolted to the block (roughly in the middle on the left side). The problem I've been having is where to mount it on this new alternator. There are two copper bolts, one is B+ where the red cable is attached, the other is connected to a black box which connects to the B+ post via a wire. None of the case screws have a nut on them, neither did my old one. The connector is a fork terminal that seems sized to fit on the bolts, though since one is connected to the other I haven't been sure that this is the solution. As I've been wanting to avoid shorting it out I've been avoiding sticking it onto things haphazardly.

I've got a meter, but I can't get her to run long enough to test anything beyond the charge in the battery, and not at all under her own power. There is no parasitic draw now, but even when slaved to another car she doesn't stay on longer than a few minutes.

Matthew A. · Post by **Matthew A.** » Thu May 09, 2013 7:01 pm

Well to hopefully make my situation a bit easier to understand, here are some images:

First the alternator:

The point on the block where the ground wire is connected:

And the connector for the ground wire:

I apologize the images aren't clearer, they looked alright when I took them, but were fuzzier than first noticed.

So that's what I'm working with when it comes to the ground.

As for the chugging I've gotten nowhere. Any ideas would be nice.

GripGreg · Post by **GripGreg** » Thu May 09, 2013 7:47 pm

UGH!! The ground connector looks really yukkie!!

Time for a change!
These relics are just that sensitive.

Matthew A. · Post by **Matthew A.** » Thu May 09, 2013 7:57 pm

GripGreg wrote:UGH!! The ground connector looks really yukkie!! Time for a change!
These relics are just that sensitive.

It's actually not in bad shape, it's just a bit dirty. Of course if I can't nail where I should be connecting it I'll never know if it's even the problem. Does no one else have a ground they can check and tell me where the darned thing goes?

GripGreg · Post by **GripGreg** » Thu May 09, 2013 8:08 pm

Clean it with the small wire or brass brush & make it look spiffy!
That way, when you find the other half, the connection will be more solid!

Matthew A. · Post by **Matthew A.** » Thu May 09, 2013 8:32 pm

GripGreg wrote:Clean it with the small wire or brass brush & make it look spiffy!
That way, when you find the other half, the connection will be more solid!

What do you mean "the other half"? The wire is still in one piece, I just don't know where it goes on the alternator.

Lesson learned: take pictures before you start pulling things apart.

KenB · Post by **KenB** » Fri May 10, 2013 2:13 am

My man,

In the first pic you posted, way over on the right side, you see that stud coming out of the alternator body? Way over on the edge. Put the other end of your ground wire from the block there and keep it in place with a nut (M4? M5? one of those metric sizes). Your current connector end isn't ideal but it should work. Ideally, you'd cut that connector off, solder on a new ring connector and use that.

If you are not grounding the alternator like this--from alt body to block-- that's one of your big problems. Your car dies out after a little while because the battery isn't getting recharged by the alternator as you drive--because it's not grounded.

KenB

Matthew A. · Post by **Matthew A.** » Fri May 10, 2013 2:48 am

KenB wrote:My man,

In the first pic you posted, way over on the right side, you see that stud coming out of the alternator body? Way over on the edge. Put the other end of your ground wire from the block there and keep it in place with a nut (M4? M5? one of those metric sizes). Your current connector end isn't ideal but it should work. Ideally, you'd cut that connector off, solder on a new ring connector and use that.

If you are not grounding the alternator like this--from alt body to block-- that's one of your big problems. Your car dies out after a little while because the battery isn't getting recharged by the alternator as you drive--because it's not grounded.

KenB

The car dies even when it's getting recharged by another vehicle. I tested the battery while slaved to another vehicle and was running a strong 13.5v and it still chugged out and died.

Additionally the connector is too big for those thin bolts. To have a wire that'd fit I'd have to replace the old one. It's sized to fit on the copper bolts, my concern is that the secondary bolt is indirectly wired to the B+ bolt. I'll give that a try anyways.

It still doesn't fix the chugging though as that occurs even when a secondary electrical source is connected and is providing enough power to run the car.

Falkenberg · Post by **Falkenberg** » Fri May 10, 2013 3:26 am

The black box with the wire from b+ is a condensor. It helps to stabilize the charging voltage ripple a bit so that you will not hear the alternator hum on your radio.
You could attach your ground wire to it's base (post) but since you have a large connector, you'll have to figure out how to make a decent fit there. Replacing the connector with a ring-type would be an option.
Perhaps your old alternator was a bit different? That could explain why you can't find now where the connector should go. Even so, any solid connection to the alternator body is sufficient to solve the charging issue.

As far as running problems, I don't think they are related. Did something else happen to the car in the mean time?

Matthew A. · Post by **Matthew A.** » Fri May 10, 2013 11:57 am

Falkenberg wrote:The black box with the wire from b+ is a condensor. It helps to stabilize the charging voltage ripple a bit so that you will not hear the alternator hum on your radio.
You could attach your ground wire to it's base (post) but since you have a large connector, you'll have to figure out how to make a decent fit there. Replacing the connector with a ring-type would be an option.
Perhaps your old alternator was a bit different? That could explain why you can't find now where the connector should go. Even so, any solid connection to the alternator body is sufficient to solve the charging issue.

As far as running problems, I don't think they are related. Did something else happen to the car in the mean time?

The only other change that's been made was the spark plugs, but we'd had those working fine when I was hunting down the last electrical gremlin I had (which was a short in the alternator diode). They aren't the correct ones, just the closest match, but since I've got the correct ones I'm going to try swapping those in today.

EDIT: As for the connector it actually fits on those just fine. I was just concerned connecting a ground to what is ultimately hooked into the battery. I'll do that today when I swap the plugs.

KenB · Post by **KenB** » Fri May 10, 2013 2:17 pm

Let me just put it this way:

Whatever other issues your car may or may not have, you will never be quite right until you ground your alternator.

KenB

GripGreg · Post by **GripGreg** » Fri May 10, 2013 4:37 pm

The 'other half' is the post it attaches to. Sorry!

Matthew A. · Post by **Matthew A.** » Fri May 10, 2013 6:18 pm

So instead of swapping plugs I just ensured the connects where tight (in case anything got loose since it'd come off the stands), attached the ground at the second bolt where the condenser is (no issues with shorts, so that's good) and double checked all my electrical connections to ensure they were good and tight.

One jump start later and she's running again. I don't know if one of the connections was loose enough to cause the problem or if it was the lack of a ground (since I changed enough variables to basically make this un-scientific and thus make the results useless).

She runs a bit rough when she starts but that's likely the oil needing to warm up first. She can now be driven and I can get her oil changed properly.