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Thread: Alternator Help!

  1. #1

    Exclamation Alternator Help!

    Got a bit of a problem..

    I had summit UDP's on my car, with just a CAI..Battery meter kept dropping at night with the lites on, and when I'd hit the brakes it got even worse(abs light would pop on, lights really dim, radio shut off). It would only do that a little bit depending on how you were driving, as in how much you were on the brakes..or if you drove a long distance, and stopped and held the brakes in, it would not do it..

    pretty sure I need to replace the alternator..

    also took the alternator pulley from summit off and threw my stock one back on for a few weeks..didn't help..

    what should I look for if I replace the alt, and it keeps doing this?
    Matt
    94 Ford Ranger
    01 KX125
    2002 Ford Mustang GT - 13.96 @ 98.8 (sold)

  2. #2

    Short

    If you replace the alt,,,,and it KEEPS doing it? Id say you have a short, or bare wire, or had a melt down, have you hooked up any crap that woulda caused this prob.. ?
    JUNK IT!

  3. #3
    Quote Originally Posted by How Much? View Post
    If you replace the alt,,,,and it KEEPS doing it? Id say you have a short, or bare wire, or had a melt down, have you hooked up any crap that woulda caused this prob.. ?
    I have a two hundred watt amp and a ten inch sub..even with it totally disconnected and wires out it still does it..
    Matt
    94 Ford Ranger
    01 KX125
    2002 Ford Mustang GT - 13.96 @ 98.8 (sold)

  4. #4
    Senior Member 85stang's Avatar
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    hada problem, the lights would dim when i hit the brakes. was a short in the wiring.
    85 mustang gt
    01 mustang
    06 F150
    65 t-bird (project)
    will:loco:

  5. #5
    On your 01? Where was it located?
    Matt
    94 Ford Ranger
    01 KX125
    2002 Ford Mustang GT - 13.96 @ 98.8 (sold)

  6. #6
    RRT juice_man_86's Avatar
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    the alternator pulley that comes with the underdrive kit actually speeds up the alternator a bit to compensate for the smaller crank pulley.
    2014 Mustang GT m6 - 12.97@111
    All stock down to the tires
    12.53 on slicks. Stock. No tune.

    1986 Mustang 5 speed - 12.10@110 off the sauce
    11.05 on Nitrous babying a hurt t-5

    327 stroker BOSS block with junk Pro Comp heads
    355hp n/a
    520hp on nitrous

    All Nitrous parts are gone. Turbo on the way

    Tuned by Tim @ Rodeheavers Hotrod & Dyno Shop

  7. #7
    Quote Originally Posted by juice_man_86 View Post
    the alternator pulley that comes with the underdrive kit actually speeds up the alternator a bit to compensate for the smaller crank pulley.
    causing the alternator to work harder then if its smaller and spinning faster?

    it seems the alternator is working too hard, or from everything i've done it is seeming to be my problem.
    Matt
    94 Ford Ranger
    01 KX125
    2002 Ford Mustang GT - 13.96 @ 98.8 (sold)

  8. #8
    NEWB daviac5000's Avatar
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    The (alternator) UDP is actually larger than stock and slows down the alternator. I threw on an overdrive pulley when I did my 3G upgrade. ASP makes one, but I also picked up one on Ebay recently. Have you checked/cleaned your grounds and other connections? If everything else looks good, have the alternator tested before you replace it.

    Dave

  9. #9
    Senior Member yellowstang03's Avatar
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    did you have a capacitor on your amp? if not and you used it alot it could have killed the altenator also. take it off and get them to check it and the battery i think they do it for free at advance.
    03 gt kb

  10. #10
    RRT juice_man_86's Avatar
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    the pulley that came with my old kit was smaller
    2014 Mustang GT m6 - 12.97@111
    All stock down to the tires
    12.53 on slicks. Stock. No tune.

    1986 Mustang 5 speed - 12.10@110 off the sauce
    11.05 on Nitrous babying a hurt t-5

    327 stroker BOSS block with junk Pro Comp heads
    355hp n/a
    520hp on nitrous

    All Nitrous parts are gone. Turbo on the way

    Tuned by Tim @ Rodeheavers Hotrod & Dyno Shop

  11. #11
    Quote Originally Posted by yellowstang03 View Post
    did you have a capacitor on your amp? if not and you used it alot it could have killed the altenator also. take it off and get them to check it and the battery i think they do it for free at advance.
    No, there was no capacitor on it..I had it disconnected for quite some time, but it kept doing it so I just reconnected it, and it never made a difference. (The system)

    Quote Originally Posted by juice_man_86 View Post
    the pulley that came with my old kit was smaller
    I hear that, but would that mean mean the alternator would work harder because its taking more revolutions to equal the equivalency of the stock pulley..correct? What kind of motor and car?
    Matt
    94 Ford Ranger
    01 KX125
    2002 Ford Mustang GT - 13.96 @ 98.8 (sold)

  12. #12
    Senior Member Ares's Avatar
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    You want atleast a 2:1 ratio for altenator and crank pulleys. Think I have my car pullied to about 2.5:1 so it's making near peak output at idle and won't be over spun untill about 8000rpm so I have plenty of room.
    Ed...
    2012 Ram 2500 4x4, 5.7 Hemi, leveled, 35" tires
    2004 Mustang GT - Comp Orange/5speed Best 1/4 11.94@113.64, 1/8 7.59@89.48, 1.57 60' - Best 60' 1.51, just a NA 2v

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