Dual Fans, upgraded alternator, still not enough charging ..

1993SSP

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I'm needing some tech help. I put a newer style, from the junk yard alternator on a fox body 5.0 for a guy. The reason for adding this is because he had upgraded to an aluminum radiator and dual electric fans. I upgraded all the wiring as needed for the new alternator with 4ga wire and a 140 amp breaker. He drove the car abour 25 miles round trip, got back home, shut off the car and it will not start back, he told me the amp guage would barely stay just above red. The paperwork with the fans stated they are 20 amp each. He has the fans wired on a relay and they run all the time. Any suggestions??
 
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HISSIN50

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Take a volt reading of the system, noting if the alternator has any output.
 

jrichker

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Also make sure that the 4 gauge ground was added.
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 a much current, so it needs to be 4 gauge too.

The picture shows the common ground point for the battery & alternator

Picture courtesy timewarped1972
ground.jpg
 

jrichker

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What should the volt reading be at the battery while the car is running? 13-14volts dc??

You should see 13.8-14.2 volts at idle. That range insures that the battery will charge properly. Most common is in the range of 14-14.5 volts at 1000 RPM.
 

montegoman351

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I'd say check the ground issue...get the car started...run it to Autozone, etc., and have them hook up the machine to it. I put a 130A alt on the Montego a while back, then I took the car down to Autozone and had them test it...it tested out 110A...as long as it's putting out at least 80% of it's advertized amperage...it's good...:nice:

Are you running underdrives? If so, that could hinder the charging system...:nonono:
 

LiquidGT

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Do you know what the alternator came out of?

Oh yeah, did you not use the stock wiring at all with the new 4ga wire? One of the regulator wires is hidden in the stock alt harness.
 

faststang90

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pulley on alt

i changed my over to 130 off a newer car dont remember what year (94-95) i think it was but it would not charge the batt. i was looking at the new alt and my old one and the newer one had a bigger pulley on it and the old one was smaller but the older one has a fan on the out side. so i took the pulley of the old one and installed it on the newer one. just check the pulley size
 

1993SSP

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Do you know what the alternator came out of?

Oh yeah, did you not use the stock wiring at all with the new 4ga wire? One of the regulator wires is hidden in the stock alt harness.


I plugged the stock harness into the new alternator, I then spliced the blk/white on the new sty alternator onto the blk/white on the original harness
 

LiquidGT

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Maybe heck the circuit breaker? I had a resettable (type III, I think) breaker in my car, it worked fine on the cooler days/months, but on really hot days the combined heat from the ambient air and engine would trip the breaker and its wouldnt reset until it cooled down. Now I'm using a fuse, it probably not the problem you're experiencing, but I'm just throwing that out there.
 

jrichker

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Do not use the stock wiring on a high current alternator. You are risking an electrical fire. The only exception is the SSP police/highway patrol vechicles that came witha a high current alternator and different wiring.

See the Stangnet 3G install sticky 3G Alternator Install: A How To - Mustang Forums at StangNet for proper wiring for a 3G or other high current alternator installation.
 

lang williams

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I graped a 3g out of a 94 T bird for my project 84...The stator wire on the alt plug was cut off an nothing connected to it. Can this be done? Is there a way to trick the alt. The black/white wire isn't even on my harness. Whats on the other end? I may have to run one to where ever it goes. FYI the car is a 84 with a 87 dash 4 cyl 5.0 conversion.
 

HISSIN50

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I graped a 3g out of a 94 T bird for my project 84...The stator wire on the alt plug was cut off an nothing connected to it. Can this be done? Is there a way to trick the alt. The black/white wire isn't even on my harness. Whats on the other end? I may have to run one to where ever it goes. FYI the car is a 84 with a 87 dash 4 cyl 5.0 conversion.

The stator loops from the S terminal on the regulator to the lone terminal on the 3G body. You don't need to use any OEM body harnesses for the stator circuit.
 

lang williams

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Thanks for the info hissin but I'm not following it. what is the s terminal? guess I just need to know what to do to make my own stator connection. I looked at the auto zone wiring diagrams an didn't see it. I didn't mean to jack this thread, but thanks for the info.
 

HISSIN50

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Thanks for the info hissin but I'm not following it. what is the s terminal? guess I just need to know what to do to make my own stator connection. I looked at the auto zone wiring diagrams an didn't see it. I didn't mean to jack this thread, but thanks for the info.

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