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Old 10-05-2011, 11:30 PM
1976flareside 1976flareside is offline
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1976 ford f100 charging issues

my 1976 f100 has a 302cid which is not the stock motor but im told had no problems before the previouse owner parked it two years ago. i purchased the truck about a month ago and the battery will not stay charged while its running. i replaced the alternator and the battery holds a good charge as long as its not running. ive checked all the grounds and traced all the wiring back as far as i can go. Any ideas or advice that anyone has would be great, thank you
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Old 10-06-2011, 06:31 AM
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Neil W. Lareau nlareau
Can't say what's wrong with yours, but I can tell you what was wrong with mine. That 45 Amp alternator just wasn't cutting it with the radio, radiator fans, and everything else. I was driving down the road with a working alternator and still drawing down on the battery.

A junkyard 3G alternator as people describe here was the smartest, easiest upgrade I've done to this truck. $20.
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Old 10-06-2011, 09:16 PM
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fmc400 fmc400 is offline
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Does this truck have an ALT light, or an ammeter gauge in the dash? There are a few wiring items to check first; if they check out then the regulator is suspect.
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Old 10-13-2011, 03:34 PM
1976flareside 1976flareside is offline
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i do have an ammeter and i have an ambulance grade alternator but if i disconnect the neg- battery cable while its running the engine dies, and i just took the alternator down and napa tested it for me and it read out good
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Old 10-13-2011, 03:43 PM
1976flareside 1976flareside is offline
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i do have an ammeter and i have an ambulance grade alternator but if i disconnect the neg- battery cable while its running the engine dies, and i just took the alternator down and napa tested it for me and it read out good
"This truck will do the speed limit on the trailer to the scrap yard"
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Old 10-13-2011, 05:23 PM
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check the fusible link that comes from the alt harness to the battery side of the starter sel.
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Old 10-13-2011, 08:47 PM
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i do have an ammeter and i have an ambulance grade alternator but if i disconnect the neg- battery cable while its running the engine dies, and i just took the alternator down and napa tested it for me and it read out good
Never disconnect the battery from a running engine. If you do this, the alternator output can jump very high, and fry any onboard electronics like CB radios, ignition modules, etc - in some cases even burn out bulbs.

Check the fusible link in between the alternator output and the battery-side of the starter solenoid for continuity. If that's fine, then have the regulator tested.
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Old 10-13-2011, 08:47 PM
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