alternator upgrade problem

[5150FOX]

Hey guys, I Recently upgraded my 91 gt alternator to a 95 5.0 alternator and now I've been over charging and burning (yes catching on fire) an inline fuse holder and now a 140amp circuit breaker. I did my homework, read and understood how to's on this forum and can't see where I went wrong.

 

[HISSIN50]

This is on a new 4 AWG or numerically smaller cable?
How are the connections made?
If using a circuit breaker, a resettable unit with screw-on terminals are desirable.
Has the alt been bench tested?

 

[5150FOX]

This is on a new 4 AWG or numerically smaller cable?
How are the connections made?
If using a circuit breaker, a resettable unit with screw-on terminals are desirable.
Has the alt been bench tested?

Yes all new size 4 battery cable from autozone.
crimped on fittings.
screw on terminals, check, pictured below but 140amp
Bench test passed all sections at autozone

 

[HISSIN50]

The crimped fittings might be an issue. Are they getting excessively hot or is the insulation on the cable near the connections discoloring?

Do you have a spare regulator you can try?

 

[4rdnut]

Get rid of that car stereo fuse holder, it says 60 amp on it, so even if you put a 140 fuse in it, the made in china fuse holder can't handle the current. You can't go cheap on electrical. You want the heavy duty mega fuse and holder from pa performance alternators. The fuse bolts down in the holder. It's a 200 amp fuse which is needed to handle the current spikes.

 

[99FiveOh]

When you say overcharging, have you put a voltmeter on the car and verified that it's over charging? Overcharging and burning wires tells me there is a short somewhere and the regulator is kicking the alt into overdrive to try and correct it. The regulator takes readings on the charging system and tries to maintain a constant voltage. If there is a drop, the regulator raises the output until it levels out again.

If there is enough juice flowing through the cable to actually ignite a fuse holder, there is a huge draw going on somewhere! I've only seen this happen when an amp wire gets caught in a door or grounds itself to the firewall.

 

[jrichker]

The stock wiring has a yellow/white "sense" wire in it. Its job is to sense the voltage drop across the alternator output wiring. Make sure all the original wiring is still connected to the starter solenoid.

You will want to check the resistance from the starter solenoid junction point to the yellow wire on the alternator plug. With the battery negative connector disconnected and the alternator 3 wire plug disconnected, you should see less than 1 ohm.

Do not connect the two 10 gauge orange/black wires to the 3G alternator. You risk an electrical fire if you do.

Any car that has a 3G or high output current alternator needs a 4 gauge ground wire running from the block to the chassis ground where the battery pigtail ground connects. The 3G has a 130 amp capacity, so you wire the power side with 4 gauge wire. It stands to reason that the ground side handles just as much current, so it needs to be 4 gauge too.

The picture shows the common ground point for the battery , computer, & extra 3G alternator ground wire as described above in paragraph 2. A screwdriver points to the bolt that is the common ground point.

The battery common ground is a 10 gauge pigtail with the computer ground attached to it.
Picture courtesy timewarped1972

Correct negative battery ground cable.

Be prepared to check a voltage drop testing of connections and grounds if the first series of tests don't find anything.

Use a Digital Volt Meter (DVM) to measure the voltage drop across a connection or wire. Adding length to the test leads may be required, and does not affect the accuracy of the test. Use 18-20 gauge wire for the test leads if you have to lengthen them.
1.) Most grounds use the negative battery post as their starting point.
2.) The voltage will be small if the ground is good: less voltage drop = better connection.
3.) Be sure that the power to the circuit is on, and the circuit is being used in its normal manner. For instance, if it is a light circuit, the lights on that circuit should be powered on.
4.) To measure grounds, place one DVM lead on the battery negative post and the other on the wire or connector that goes to ground.
5.) Read the voltage drop: Light duty circuits (1-5 amps) should show .1-.25 volts. Medium duty circuits (6-25 amps) should show .25-.5 volts. Heavy duty circuits (26 amps up) should show .5-.75 volt drop. A voltage drop lower that spec is always acceptable.
6.)
See http://assets.fluke.com/appnotes/automotive/beatbook.pdf for help for help troubleshooting voltage drops across connections and components. .

 

[99FiveOh]

It's so easy to install these alternators on Fox cars it's ridiculous! The "D" shaped regulator plug is untouched in the installation which only leaves the stator wire and the 4 gauge charge wire. Connect the stator wire to the white wire coming from the "D" shaped connector and run the 4 gauge wire to a fuse holder and to the battery and you're done.

 

[5150FOX]

I've got it set up to go back to stock so that's what I'm going to do for now,because the car is still 98% stock and doesn't need that kind of power yet. Thanks for all of your replys and its definitely something to look up for later.