87-93 130amp Alternator Install How-to

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MUSTANG 130 AMP ALTERNATOR INSTALL (87-93)

The factory 75 amp alternator used in the 1986-1993 Mustang 5.0L was, to put it mildly, undersized. Add on something as simple as underdrive pullies or an electric cooling fan and you've effectively killed the ability of the alternator to keep the battery charged. Luckily, turn-key solutions like our SVE 130 Amp Alternator Upgrade Kit exist to solve problems just like this. Watch the video for full instructions on how to install this kit on your Fox Mustang!
 
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Noobz347

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Great video. I'm a little concerned about the basic upgrade kits though. Those skinny little black/orange wires are barely able to keep up with the factory load and 2G alternator.

A drained battery and 130 amp alt at 2k is probably enough to set them on fire.
 

jrichker

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Missing from your Video:
The secondary power ground is between the back of the intake manifold and the driver's side firewall. It is often missing or loose. It supplies ground for the alternator, A/C compressor clutch and other electrical accessories such as the gauges. Any car that has a 3G alternator needs a 4 gauge ground wire running from the block to the chassis ground where the battery pigtail ground connects.

Problems observed with the video:
This keeps popping up. I am amazed at the number of people that don't understand that wiring MUST be properly sized to match the current that it is supposed to carry. A 4 gauge wire is the minimum size for a 130 amp alternator, and then only is it s a short length of wire, less than 10 feet.

wire-gauge-current-capacity-and-lenght-chart-gif.53745.gif


Under no circumstances connect the two 10 gauge black/orange wires to the 3G alternator. If the fuse blows in the 4 gauge wire, the two 10 gauge wires will be overloaded to the point of catching fire and burning up the wiring harness.

Here is the reasoning behind using only a single 4 gauge fused power feed to the alternator. If you use the two 10 gauge black/orange wires in addition to the 4 gauge wire, you have two fused power feed paths. The total current capacity of the wiring is the sum of the fused paths. The 4 gauge path is fused for 125 amps, and the two 10 gages wires are fused for 60 amps. That is a total of 185 amps, which exceeds the capacity of the alternator. Overload can occur without the fuses blowing, damaging the alternator.

Don't believe me? See http://physics.bu.edu/py106/notes/Circuits.html

The worst case scenario is that the alternator develops an internal short to ground resulting in a catastrophic failure. The initial short circuit surge current is limited by the resistance of the wiring. The current in a parallel circuit divides up according to the resistance of the branches. If the 4 gauge fuse opens up first, the two 10 gauge black/orange wires will be carrying the short circuit surge current. Depending on the time lag of the fuse links, they may open up before a fire starts or they may not.
 
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Foxystang87

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MUSTANG 130 AMP ALTERNATOR INSTALL (87-93)

The factory 75 amp alternator used in the 1986-1993 Mustang 5.0L was, to put it mildly, undersized. Add on something as simple as underdrive pullies or an electric cooling fan and you've effectively killed the ability of the alternator to keep the battery charged. Luckily, turn-key solutions like our SVE 130 Amp Alternator Upgrade Kit exist to solve problems just like this. Watch the video for full instructions on how to install this kit on your Fox Mustang!
 

Jarhead67

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Missing from your Video:
The secondary power ground is between the back of the intake manifold and the driver's side firewall. It is often missing or loose. It supplies ground for the alternator, A/C compressor clutch and other electrical accessories such as the gauges. Any car that has a 3G alternator needs a 4 gauge ground wire running from the block to the chassis ground where the battery pigtail ground connects.

Problems observed with the video:
This keeps popping up. I am amazed at the number of people that don't understand that wiring MUST be properly sized to match the current that it is supposed to carry. A 4 gauge wire is the minimum size for a 130 amp alternator, and then only is it s a short length of wire, less than 10 feet.

wire-gauge-current-capacity-and-lenght-chart-gif.53745.gif


Under no circumstances connect the two 10 gauge black/orange wires to the 3G alternator. If the fuse blows in the 4 gauge wire, the two 10 gauge wires will be overloaded to the point of catching fire and burning up the wiring harness.

Here is the reasoning behind using only a single 4 gauge fused power feed to the alternator. If you use the two 10 gauge black/orange wires in addition to the 4 gauge wire, you have two fused power feed paths. The total current capacity of the wiring is the sum of the fused paths. The 4 gauge path is fused for 125 amps, and the two 10 gages wires are fused for 60 amps. That is a total of 185 amps, which exceeds the capacity of the alternator. Overload can occur without the fuses blowing, damaging the alternator.

Don't believe me? See http://physics.bu.edu/py106/notes/Circuits.html

The worst case scenario is that the alternator develops an internal short to ground resulting in a catastrophic failure. The initial short circuit surge current is limited by the resistance of the wiring. The current in a parallel circuit divides up according to the resistance of the branches. If the 4 gauge fuse opens up first, the two 10 gauge black/orange wires will be carrying the short circuit surge current. Depending on the time lag of the fuse links, they may open up before a fire starts or they may not.

I installed a 130 amp alternator, and the instructions said to hook up the two 10 gauge black wires; but you're giving a compelling case as to why I shouldn't. Should I just disconnect them from the alternator and tape them up? Did they run to the starter solenoid also, and if they do should I disconnect them there also? If I don't use them will the 4 gauge wire complete the circuit that the 10 gauge black wires did?
 

fredfifty

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^this. i have the 10 gauge power wire attached to the 3g alternator post, along with the 4 gauge power wire...so the power post on the 3g should only have the 4 gauge power wire ONLY? take off and tape off the 10 gauge (black/orange stripe) power wire?
 

Jarhead67

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^this. i have the 10 gauge power wire attached to the 3g alternator post, along with the 4 gauge power wire...so the power post on the 3g should only have the 4 gauge power wire ONLY? take off and tape off the 10 gauge (black/orange stripe) power wire?
I did as described above by Jarrod & Jrichter, and everything is good. I taped the two black/orange wires and zip tied them out of the way
 

Reddevil91

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So I did my 3g alternator like they said to do on the lmr video, then added 4g positive and negative cables. My friend got his installed by somebody for him and they def did it different than mine. Looks like they just pulled all the old wiring from the alternator out, Then just ran the 4g wire with fuse and spliced in the 3 wire connector but ran the white wire to the other plug. Is this correct?
46015281-3347-4C7D-8E21-5BF39E6724B7.jpeg
 

Jarhead67

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So I did my 3g alternator like they said to do on the lmr video, then added 4g positive and negative cables. My friend got his installed by somebody for him and they def did it different than mine. Looks like they just pulled all the old wiring from the alternator out, Then just ran the 4g wire with fuse and spliced in the 3 wire connector but ran the white wire to the other plug. Is this correct?
46015281-3347-4C7D-8E21-5BF39E6724B7.jpeg
Just use the supplied 4g wire, disconnect the two black/orange wires at the alternator and tape them up. That way the 4g wire takes the whole load and you don’t run the risk of a wire fire.
 
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Reddevil91

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Just use the supplied 4g wire, disconnect the two black/orange wires at the alternator and tape them up. That way the 4g wire takes the whole load and you don’t run the risk of a wire fire.
Cool thanks, so Can I just pull them out completely to clean up the wiring mess? Trying to somewhat clean up what I can. I’d really like to also clean up the vacuum tree wiper motor area also but yeah that’s a different story.
 

Jarhead67

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Cool thanks, so Can I just pull them out completely to clean up the wiring mess? Trying to somewhat clean up what I can. I’d really like to also clean up the vacuum tree wiper motor area also but yeah that’s a different story.
That's completely up to you. All I did was cut off the ring connectors (at the alternator) and put heat shrink on them to keep them from accidently shorting, then tucked them into the loom that they're in. I believe the other end goes to a fusible link at the + side of the Starter solenoid. I left that hooked up as I wasn't sure if any other circuits connected to that fusible link.
 

Reddevil91

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That's completely up to you. All I did was cut off the ring connectors (at the alternator) and put heat shrink on them to keep them from accidently shorting, then tucked them into the loom that they're in. I believe the other end goes to a fusible link at the + side of the Starter solenoid. I left that hooked up as I wasn't sure if any other circuits connected to that fusible link.
Gotcha that’s true guess that’s where the good old @jrichker comes into play for that knowledge to see if it would cause any problems. Don’t think it will but idk lol, just know they pulled all that out on my buddies and it runs fine.
 

Wayne Waldrep

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@jrichker Since this is a sticky, I'd also like to know your answer to the last couple questions regarding complete removal of the black/orange factory wires. Seems many people have eliminated all of this. I'm editing this to include this text from the other 130amp install thread that's also a sticky. "Once the location of the 10g wire has been found, cut the union and tape or use a butt join to cover up the end of the 10 gauge wire. This wire will still have power since we will need to leave the wire hooked up at the starter solenoid due to the voltage sensing wire that shares the fuse link."
I'd like to go back and check my install but before I do I'd like to know the best way. Capped at the alternator end or complete removal.
Thank you, sir.
 
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jrichker

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. The yellow/white wire is the voltage sense and power for the field. There is a fuse link embedded in the wiring where it connects to the black/orange wiring. It connects to the starter solenoid so that it can "sense" the voltage drop across the output wiring from the alternator. That's why you don't cut the black/orange wires off at the starter solenoid,

Alternator wiring diagram for 87-93 Mustangs.
 

Blown88GT

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This is also shown in Ford's EVTM. Fuselink "F" feeds power to Fuselink "E". Removing the Black/Orange wire from the starter relay will disconnect the Yellow/White wire & the battery will not charge at all. Edited picture doesn't not show the required fuse on the new 4AWG wire.
EVTM_p012a.jpg
 

Wayne Waldrep

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Sorry. I still don't see what the black/orange wires are doing up until the fuseable link. If they are left unhooked then how can they be doing anything? Looks like the yellow/white wire is the one that stays. Just trying to get it right.
 

Blown88GT

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I provided a simple explanation & gave you a picture.
jrichker explained it , too.

Let's try this.
The black/orange wires aren't doing anything because they are no longer connected to the alternator. They only maintain the fuselink connections from the regulator "A" terminal to the battery via the yellow/white wire. If you remove the black/orange at the starter relay, how would you get battery voltage to the yellow/white unless you cut it at the E to F junction & tie E back on the battery at the relay..

If this isn't clear Google "voltage sensing power supply" or read this.
https://www.acopian.com/remote-sensing.html
 
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Wayne Waldrep

Before I post a pic, do you have one of yours?
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I provided a simple explanation & gave you a picture.
jrichker explained it , too.

Let's try this.
The black/orange wires aren't doing anything because they are no longer connected to the alternator. They only maintain the fuselink connections from the regulator "A" terminal to the battery via the yellow/white wire. If you remove the black/orange at the starter relay, how would you get battery voltage to the yellow/white unless you cut it at the E to F junction & tie E back on the battery at the relay..

If this isn't clear Google "voltage sensing power supply" or read this.
https://www.acopian.com/remote-sensing.html
Thank you.