won't fully charge
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Senior User
Joined: May 2004
Posts: 149
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From: Spokane
won't fully charge
1967 f-100 with a 360 from a '71. New alt., battery, belt, and voltage regulator. ALT. dash light stays on through all tests. Alt. will NOT charge past 12.50V. Under full load, voltage drops to 12.36 steady, back to no load 12.51 steady. holding high RPM doesn't change it. Engine not running 12.50 till i hook up jumpers, then it hits close to 14V.
just bench tested the alternator @ 2 different parts stores. NAPA said it's good, and motion said it's putting out 13.8V.
I am stumped, and I have my auto tech. teachers stumped. Wires look good, terminal is clean and batt. cables are new.
any ideas????
just bench tested the alternator @ 2 different parts stores. NAPA said it's good, and motion said it's putting out 13.8V.
I am stumped, and I have my auto tech. teachers stumped. Wires look good, terminal is clean and batt. cables are new.
any ideas????
Thread Starter
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Senior User
Joined: May 2004
Posts: 149
Likes: 0
From: Spokane
update...... checked, rewired and secured all the wiring in the engine compartment...checked all the grounds I could find. still has the problem, and the ALT light still shines bright.
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Joined: Jan 2001
Posts: 56,999
Likes: 2,747
From: Virginia
This is how it's wired, but your wire colors may be different.
You need to get a voltmeter and start doing some testing.
Put the negative meter lead on the case of the regulator when testing the wires at the regulator.
unplug the regulator plug and make sure;
1. With the truck off, make sure you have 12 volts on the "A" terminal of the regulator plug.
2. With the key in run, but the engine not running, make sure you have 12 volts on the "I" terminal at the regulator plug.
You need to get a voltmeter and start doing some testing.
Put the negative meter lead on the case of the regulator when testing the wires at the regulator.
unplug the regulator plug and make sure;
1. With the truck off, make sure you have 12 volts on the "A" terminal of the regulator plug.
2. With the key in run, but the engine not running, make sure you have 12 volts on the "I" terminal at the regulator plug.
Thread Starter
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Senior User
Joined: May 2004
Posts: 149
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From: Spokane
been searching the forums all day, and that's the best diagram I've seen for my set up. Thanks, and I'll probably wait for daybreak to check the wires. I have a MAC multimeter, so that won't be a problem.
Moderator
Joined: Jan 2001
Posts: 56,999
Likes: 2,747
From: Virginia
The "I" does not look correct. Do you have a testlight or a small bulb you could rig into the "I" terminal to simulate the diagram? Instead of going to the ignition switch, just touch it to the battery +, and with the truck running, see if it will start charging.
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Thread Starter
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Senior User
Joined: May 2004
Posts: 149
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From: Spokane
Found and repaired the problem!!!!!! The replacement alternators are just a bit bigger than the original, so while installed one of the bolts was touching the block. My electrical sponsor fabricated a new mounting bracket for the bottom of the alt. and now it's charging GREAT!!! thanx for the help!
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