Alternator charging question - Ford Mustang Forums : Corral.net Mustang Forum
 
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post #1 of 6 Old 08-03-2011, 08:40 AM Thread Starter
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Alternator charging question

Just had a waking thought, as I start my a.m. Coffee
---Not a good one, regarding my recently RE-replaced alternator,
---And whether or not it fixed my electrical gremlin, from June's road race on Sunday.

To set stage
Car was 140,000 miles old, & no electrical gremlins in the build, till last fall Car quit on me, after turn 8 , at a different track
---started sputtering (worse with foot in gas, rpm's better as i lift to a cruise) (quickly progressed to the point I had to lift to an IDLE , for the bogging rpm's to recover)(then the tach PEGs past redline, and car dies)
---i had to have the alternator rebuilt.
---Ran fine thereafter, till Sunday in June at RA

June race at road Atlanta:
Saturday, car ran fine till it was overheating to 240*F, and I bailed out of race. (whole other story, in another thread)

Sunday, before MY qualifying, . . .
The car died (on a buddy who was trying her out), between turns 10a & 12, : "it felt like someone hit the kill switch"
##-he tried to restart, and it didn't even click, IIRC.
##- then he sat there on grass for 15", and the it finally restarted, & he came back to the pits.

Next day:
Car ran fine for qualifying, for me: I posted my new best time (not super fast)(but a new best FOR ME).

Got to grid WAY TOO EARLY for race
~20" early?!?

For better or worse, I killed the motor
---And sat there for 20-25" with cool shirt pump, and cool helmet fan running, JUST on the full sized battery.

Made it one lap into race, and it starts sputtering in the esses, and dies at turn 5,
Acting and feeling JUST LIKE it did when the alternator died the 1st time.

Tow back to paddock, car sits, starter clicks, just like a dead battery
Throw in a 30" charge
It starts right up

Back home:
On that same short 30" charge which let me get the car on the trailer:
---I was able to drive it 5 easy miles to maaco for paint, they had to drive it a few blocks twice.
---then I was able to drive it 15 easy miles to the vinyl wrap place.
---then I almost made it home, put my foot in it on the interstate, and it sputtered, seemed to lose some spark.
---lifted my foot to cruise, all seemed fine,
---made it 5 more miles, started sputtering, tach pegged past red line, and dies (exactly how it did with the first alternator death, and exactly how it did Sunday at race)

Walked to warehouse (5 blocks away)
Got bettery charger and extension cord
40" charge and it started right up.

it NOW has a buddy's "2 month old" alternator.


Now, . . .
for the question:

If I am running underdrive pulleys (which I am)
steeda 25% Under drives

Might that spin my alternator more slowly?
(yes)(I think)

BUT, . . .


Could THAT account for the voltmeter to read low? (autometer, on my dash was reading ~11.8)

And possibly accounting for the shop thinking the old, but freshly rebuilt one, to appear to not be charging?

Reason for worry is that I haven't had a chance to lean hard, on it, to see if it has the goods, and race thus weekend

Voltmeter reading 11.8ish still

Not sure if that is the underdrive pulleys
Or a lingering gremlin
Or expected, to have subpar output with underdrives

Don't really want to wait till RACE day to decide, but am out of time

THOUGHTS?????

Long, but thanks for sticking with me if you are still here

Thx,
Doc

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post #2 of 6 Old 08-03-2011, 10:02 AM
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wow, lol, did you check the outputs with a know good quality volt meter at the alternator post, battery posts and behind your gauge wiring, varying rpms, temps, etc? Where is your battery located? Did you check and are running the proper grounds? Is all the battery wiring the proper gauges? More info (im scared to say that, lol) may help.

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post #3 of 6 Old 08-03-2011, 11:00 AM Thread Starter
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Thx for finishing
Gonna go get my own voltmeter
And take some numbers, as you described, in case I need 'em, for a shorter addition to this long mini-thread.

Other input still welcome

God let me finish the 4 quals/races this weekend
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post #4 of 6 Old 08-04-2011, 12:34 AM
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What model Mustang? I have a 93, 130A alternator swap. The gray plug/connector had a wire break. They were very brittle. Probably not your issue, but it's free to check.

Once at Willow Springs, my car kept dying each time I'd go WOT in 4th gear. It ended up bring one of the wires to the MSD ignition box grounding on the C/C plate.

Sorry for the lack of tech and just 2 personal experiences.

1993 GT 310rwhp / 351rwtq
AFR FTI EDEL Combo. MM, T-56 3.73, Brembo, 275s on 03 Cobras all around
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post #5 of 6 Old 08-04-2011, 09:43 AM
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Have you thought it might be a heat related issue? It seems to me every time it acted up it had been running for a while and then it recovered after it had sat long enough to cool off.

I had a TFI in my '95 go and it would run fine to 4000, then just wouldn't pull anymore. I don't imagine that works any better on a road course than it does a drag strip.

steve

83 & 84 GT turbos, 85.5 & 86 SVOs
93 5.0 notch, 95 GT vert & coupes, 96 GT vert
87 & 88 Thunderbird TurboCoupes
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post #6 of 6 Old 08-06-2011, 10:01 AM
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Quote:
Originally Posted by teal95 View Post
Have you thought it might be a heat related issue? It seems to me every time it acted up it had been running for a while and then it recovered after it had sat long enough to cool off.

I had a TFI in my '95 go and it would run fine to 4000, then just wouldn't pull anymore. I don't imagine that works any better on a road course than it does a drag strip.

steve
Not ruling out heat, but a bad TFI would not cause the "no click" when the key is turned to activate the starter.

It doesn't take much to blow out a regulator. I don't know about RE, but the regulators included in parts store rebuilds are junk. The diode packs just don't hold up. I went through many parts store regulators. Do yourself a favor and go to the Ford parts counter and get a good regulator. In my experience, they will provide full voltage sooner and will last. While I was having problems, I kept a spare regulator in my spares box for the track. Since I installed the Ford regulator, I never used the spare.

Eric Anderson
Alpharetta, GA

At Corner-Carvers, we're not happy till you're not happy
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