73 Dart Alternator doesn't show charge anymore.

[SputnikOne]

Hey all, replaced the electrical fuel pump on my Dart last week to a mechanical one and taped off the power wire that went to it with electrical tape, the ammeter was reading normal for abit but now it won't show charge even if I give it gas, it shows discharge when I turn things on, and then goes back to just below zero and stays there.

 

[dano]

Disconnecting a power wire should not change your charge circuit unless its grounding out. You should do something more than electrical tape, like sealing shrink tube, etc.

Have you measured the battery voltage at the battery? There are several things that can cause this, bad alternator, voltage regulator, dirty battery connectors, are just to name a few. Is your car all stock?

 

[MadScientistMat]

Try pulling the fuel pump fuse and see if the problem goes away - that would be a quick way to make sure the wire isn't grounding out

 

[SputnikOne]

I'll have to check the fuses, judging by the "craftsmanship" of the previous work I discovered I'm not too sure there's even a fuse for it, there is one of the fuses that has wires going to it like it's added on, I'll try that one.

 

[Mattax]

Is your car all stock?

I agree that this is the starting piont.
Figure out what was done and where that wire was attached.

It's possible, especially if the pump was in the engine compartment, that the installer branched off of the 'ignition' feed. I put ignition in quotes because that circuit was used to power the ignition itself, the alternator field, and depending on the year etc also powered a throttle stop solenoid, electric choke assist and maybe some emissions items.

IIRC the ignition circuit and its branches do not have fuses in 1973.
The fuel pump could have pulled power from a fuse. If it did, then it would have been fed from the switched 'Accessory' feed.

 

[SputnikOne]

How would I figure out what that fuse is for? Just pull it and see what doesn't work anymore when I start the ca

 

[Mattax]

Do you see a new fuse somewhere?
Or at the fusebox do you see a new wire added?

 

[SputnikOne]

Yeah, there's one fuse with a red wire that comes off of it, same color as the one used for the pump, not that I think I can really trust the color.

 

[Mattax]

Yeah, there's one fuse with a red wire that comes off of it, same color as the one used for the pump, not that I think I can really trust the color.

Agree, you can not trust the colors. Chrsyler used red wires too.
Are you looking at the fuse box or at an inline fuse?

 

[SputnikOne]

Fuse box under the dash

 

[Mattax]

Fuse box under the dash

OK. Lets look in the books.

 

[Mattax]

In the mean time, start where its more likely to be related to the problem.
The alternator is not producing power or not producing enough power.
If you have a voltmeter, then that can be used to help diagnose.
If not, or if its not handy, start with the wire that you taped. Where does it come from?
Also look at the wires connecting to the alternator.
There is one that feeds power to the rotor (blue wire) and one that connects the rotor to the regulator (green wire). Both of them go through an extra connector near the back of the engine. make sure they are connected and in good shape.

Check the alternator output wire. Its connects to the 'Batt' terminal on the alternator and also goes through the engine connector. Do not let this one touch any metal. It is connected to the battery positive at all times. if you need to work with it, disconnect the battery..

If you post some photos, that may help us too.

 

[Mattax]

In the mean time, start where its more likely to be related to the problem.

The reason I wrote that is with '73 is that the fusebox is not illustrated the same way it was in the earlier books. We have to go back and forth betwqeen pages to figure out the circuits.

There is a 12 gage red wire with a white stripe that feeds that feeds the fuses that are always hot. Nothing to be gained by messing with that.

OK there is also X1, a red 16 gage wire coming from fuse 4. That's standard from the factory.

X1 goes to the cigar lighter and some options like map light.
But Fuse 4 also feeds M1 which includes the dome light. So if the dome light works, then that fuse is OK.

 

[SputnikOne]

Some other hints while I can't really troubleshoot right now, before when I bought the car it had some other strange electrical bugs, like the blinker pace speeding up when I stepped on the gas, or slowing significantly with the lights turned on, the hazards only work with a blinker turned on. The pump was wired in a way so that it running on whatever key position is just before the ignition position, with all the other accessories.

 

[Mattax]

From your video, it seems everything you checked was working normal other than the alternator circuit.
The battery was powering the ignition which takes very little current, and that's what the ammeter showed.
When the lights were turned on, the ammeter showed more power being drawn from the battery.

The open white circles and squares represent connectors. The 'engine connector' is a common location for problems to develop on the cars that have them.

Look around the right rear of the engine.

 

[Mattax]

Some other hints while I can't really troubleshoot right now, before when I bought the car it had some other strange electrical bugs, like the blinker pace speeding up when I stepped on the gas, or slowing significantly with the lights turned on, the hazards only work with a blinker turned on. The pump was wired in a way so that it running on whatever key position is just before the ignition position, with all the other accessories.

Might have been drawing enough power that at the alternator could not supply the system at 14 Volts, but as engine speed increased the alternator could supply everything.

This where having a handheld voltmeter in addition to the dash ammeter can be helpful.
if the ammeter is showing increased charging with increasing engine rpm, then the question is whether This is because the battery was low, or because the alternator is not being properly regulated.
Checking the voltage with the engine at higher rpm will show whether the regulator is providing proper control.

 

[SputnikOne]

Okay, I'll borrow a voltmeter from my work and see if I can grab a friend to help test it, I should just be looking at the batteries cottage and see how it changes around the normal (12?)

 

[Mattax]

Now that problem is gone.
The problem now is the alternator is not supplying power.
I would be looking at the wires for something disconnected.
Then a voltmeter could be helpful when testing, so having one on hand wouldn't hurt.
But right now I'd start with checking hte wires for a failed connection, and looking for modifications the previous owner may have done. Post photos and people here can help.

 

[Mattax]

When the car is running normally the alternator produces power at 14 Volts more or less.
Current flows as shown by the orange arrows.
With the lights on current flow would look like this

When you turned the lights on, the ammeter went from less than 5 amps discharge to 15 amps discharge. So the engine was running on the battery and then the lights were also pulling from the battery.

This could be because the alternator or the regulator had an internal failure.
Or it could be the alternator output wire, or either of the field wires (blue and green) are disconnected.

 

[Mattax]

PS. Borrow a battery charger and give it slow charge.
The last thing needed is to run the battery down and then when the problem is solved and the alternator is working, have it damage the circuits.

 

[67Dart273]

You HAVE to check battery voltage, both after night to see if it's charged, and when running to see if it's charging. it might be as simple as the ammeter is stuck.

Then we can do something

 

[SputnikOne]

Yeah, couldn't get around to borrowing the voltmeter today, gonna have to see if I can get it tomorrow or over the weekend, will keep y'all updated.

 

[Mattax]

Watching the video we see the ammeter is working. There really is no question about it. A voltmeter can confirm it and help with some troubleshooting, but its not needed. All of the major possibilities can be checked by looking and some simple tests.

 

[dano]

Props to Mattax for the help.

When owning one of these cars, you really should own a voltmeter, a cheap one will do. A timing light, vacuum gauge, and optionally a test light.

 

[SputnikOne]

Hey all, still no luck on getting a hold of a voltmeter, but I went out and took photos of just about every piece of electrical spaghetti I could find, I understand "replace all of it" is probably the preferred solution, but I'd like to get it working again atleast for now.