Question about 1991 Ford F250
New battery, new alternator and clean grounds and terminals. truck still reads 12.2v running and slowly drops until truck quits and not enough charge to start. only while key is on or truck is running. battery holds charge with ignition off.
Your truck may have an external voltage regulator. If it does, it will be found under the hood on the passenger side fender well. It's usually silver aluminum with Motorcraft on the top (if it's OEM). The regulator is the likely culprit by the sound of things.
Posted on Feb 13, 2014
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Posted on Jan 02, 2017
It appears that the alternator is still not charging the battery.Charge the battery up,and refire the truck.Check voltage with a voltmeter,directly off the back of the alternator.Most all alternators of your year model have the voltage regulator built into the alternator.If the alternator isn't producing any voltage,then it is bad,even if it is new.I have had defective new parts before.
Posted on Aug 10, 2008
You need to have the alternator re-checked and be sure the wiring is clean & correct. If an alternator is working properly & wiring is correct, those batteries should be charging as you drive.
Posted on Nov 27, 2008
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