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Charging/3G HELP!

1K views 11 replies 7 participants last post by  84tc302 
#1 ·
'93 GT

So I'm just finishing up my project. With the new motor I've hidden the wires and relocated the battery out back using buffhomer's (sp?) method with a cut-off switch. Used 1/O from cut-off switch to solenoid, and from battery + to opposite side of the cut-off switch from where the solenoid wire is. I then have 2ga from the battery nagative to the quad shock bracket finally there is 4ga from the alternator to the 150amp circuit breaker and then 2ga from the breaker to the back of the car and attached to the same side of the switch as the + battery wire. All connections are soldered using the correct size lugs for the cables. I also used welding cable throughout.

So here are the symptoms I'm currently experiencing:

When I first fired up the car with the new motor I had the stock battery and everything appeared to be charging correctly. After a couple starts and right before we were supposed to load the car up to go to the dyno I noticed that it was charging at maybe 10 volts at the most (second line on the gauge). The first dyno went well but it kept getting more and more difficult to start. A friend had a known good alternator so I installed it and fired it up. The gauge showed that it was charging correctly. I gave the car a rev and the gauge dropped back down to where it was previously (around the 9-10 volt mark). So I figured I'd take it up to Vato Zone to have them run a battery/charging test. On my way up there, which is maybe 2 miles at the most from my house I see the gauge jump up to where it is should be (tad bit over half way) for a few seconds then jumped back down to the second mark. By time I got to the store the gauge was pretty much at the bottom. We tried to test but the battery was to low and the alternator wasn't charging at all. So the guy jump starts me and I head home. I made it about half a mile before the car died. Obviously it was running off the battery and that had finally died. So fast forward to when I finally get it home. I looked at the circuit breaker and it was tripped. I try to reset it and it wouldn't stay. Pulled the breaker off the car and it was fried.

So I went and bought another breaker and a 3G alternator. I tested the yellow/black, green/red wires which all checked out (1993 Mustang---Alternator not charging----PLEASE HELP - Mustang Forums at StangNet). I made sure the battery was fully charged and started it up again. The gauge went up to a little bit above the half mark and all looked good. Took it for a spin and maybe half a mile from my house the gauge went back down to the second mark. When I got home I checked the breaker and now the new one is not tripped but I can't push the button to manually trip it like it is stuck in the non-tripped position. I checked all the cables and non of them felt even close to warm. I drove it a little yesterday and the gauge stays on the second mark and hasn't appeared to be running strictly off the battery...yet. I have checked resistance in all the cables and there isn't any open grounds.

I bought a 175amp fuse yesterday to try but I was hopping that someone here might have seen this before and could point me in a direction of some sort before I start comparing the advantages of selling this thing over digging through the miles of wiring.

Thanks in advance!
 
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#3 ·
I started out trying two known good stock alternators. Then went with a 3G. The same thing has happened with all three. What resistor are you referring to? I know there is one from the factory in the dash for the battery light which is excitor green/red wire correct? I don't recall reading that there needed to be another one.

Thanks for the quick reply!
 
#6 ·
Run two 4 or 6 gauge wires one on each side of the engine block to the chassis somewhere. Make sure it is cleaned and free of paint where ever you attach each side to. Sounds like high resistance in the ground circuit to me. Not sure tho without being there. Touch your volt meter to the alternator housing and the negative to the chassis in a good spot and see if you get a voltage reading. If you do, then you have high resistance or an open in your ground circuit. Just a suggestion.
 
#7 ·
I have a ground from the injector harness to the passenger head and one from the front drivers side of the block to one of the sway bar mounting bolts. From my understanding these cars can use all the ground help you can give them so I will add another from the passenger side of the block to the frame and then run one from the battery ground out back up to the block. Do you think that will be sufficient? Thanks for the advice!

Trey
 
#8 ·
have the same wiring setup except i went 4ga from alt to 150circuit breaker and 4ga from breaker straight to pos. battery post, 1ga from pos. battery post to 200amp breaker, 1ga from breaker to cutoff switch. 1ga other side of cutoff to solenoid. and 3/0 welding cable nfrom bellhousing bolt straight to bat. neg post. 1990fox with 3g 130amp 1 wire.
I would say try to run your alt charge wire to battery and not cutoff switch? something to try anyways. good luck!
 
#11 ·
I had the same thing happen to me a few years ago and it was a grounding problem.
 
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