Alternator cutting out - Ford Mustang Forums : Corral.net Mustang Forum
 
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post #1 of 3 Old 07-30-2011, 12:45 AM Thread Starter
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Alternator cutting out

My car just started doing this the other day and I'm not sure what would cause it. It should be noted that I currently have a Mickey Mouse 75amp reman alternator. I plan to do a 3G swap when funds permit.

The car seems to charge fine at idle, but when I start moving, 8 or 9 times out of 10, it'll drop out. The voltmeter in the dash drops to the 1st notch below half-way and the battery light will flicker and eventually stay on. As i go along, the needle will slowly creep down toward the next notch. It doesn't seem to be a fault in the instrument cluster, because noticed that my electric windows aren't as fast when this happens.

Within seconds of returning to idle, the voltmeter will jump back up and the battery light will turn off. I can push the clutch while moving and get a similar effect. Raising the engine to cruise RPM while standing still does not replicate this.

I took the alternator by Autozone, and it passed their test. I don't know it their tester failed to detect my issue or if something else is causing this. Has anyone run into a similar situation?


- '90 Mustang 5.0 LX Hatch "Ana"
H/C/I 302 with a 76mm Cartech Outlaw turbo kit, G-Force T5, plenty of MM parts... basically a budget pro-touring foxbody project
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post #2 of 3 Old 08-06-2011, 06:03 AM
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The stk rating for a 94/95 Mustang GT alternator is 130 amps. Upgrade your alternator to the correct specs and then determine if you have a problem.


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post #3 of 3 Old 08-20-2011, 09:40 AM Thread Starter
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130 amps might be stock for the 94 and 95s, but I have a '90, and 75 amps is stock for Fox-bodies. I'd like to upgrade, but funds currently don't permit that.

Either way, it was the alternator that went bad. When it stopped charging at idle, I went back and it tested bad. I can only infer that Autozone's tester spins the alternator to about idle speed. Hope someone'll find that bit of information useful.

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H/C/I 302 with a 76mm Cartech Outlaw turbo kit, G-Force T5, plenty of MM parts... basically a budget pro-touring foxbody project
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