390 FE not charging!
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Senior User
Joined: Aug 2007
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390 FE not charging!
Okay so im very new to FE's let alone Fords. I have a 1977 Ford F150 4x4 with a 390. I have replaced the alternator, battery is good, and i think its the Voltage regulator? its on the passenger side fender. but no matter what I do, the ALT light is on in my truck and its only putting out 12 Volts. Is the Alternator supposed to be grounded?? because there is a prong on the back that Says: "ground" but if so where does it ground to?! Thanks!!
Post Fiend
Joined: Mar 2004
Posts: 6,056
Likes: 8
From: Union, Washington
This is not FE specific, all charging systems work the same. Why didn't you troubleshoot the problem before doing a shotgun fix by starting to replace parts haphazardly? The wrong ones to boot. You can check alternator output by jumpering from the field to the stator pins in the regulator plug (wiring harness). If you get 16.5 volts or above your alternator is good and you need to look at the battery (charge it overnight and then load test it or at least voltage test it, 12.6 volts and above is good. Then starter load test it by leaving the voltmeter on the battery and crank the starter for 10 seconds. The voltage should not drop below 10.5 volts while cranking.) and if the battery is good then replace the regulator.
Thread Starter
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Senior User
Joined: Aug 2007
Posts: 215
Likes: 0
This is not FE specific, all charging systems work the same. Why didn't you troubleshoot the problem before doing a shotgun fix by starting to replace parts haphazardly? The wrong ones to boot. You can check alternator output by jumpering from the field to the stator pins in the regulator plug (wiring harness). If you get 16.5 volts or above your alternator is good and you need to look at the battery (charge it overnight and then load test it or at least voltage test it, 12.6 volts and above is good. Then starter load test it by leaving the voltmeter on the battery and crank the starter for 10 seconds. The voltage should not drop below 10.5 volts while cranking.) and if the battery is good then replace the regulator.
I did troubleshoot it originally, the previous alternator did do anything and infact was making noise. The regulator has been replaced, I already did a load test on the battery, its 12.8Volts. I havent done it while cranking yet, ill try that in the morning
Thread Starter
|
Senior User
Joined: Aug 2007
Posts: 215
Likes: 0
This is not FE specific, all charging systems work the same. Why didn't you troubleshoot the problem before doing a shotgun fix by starting to replace parts haphazardly? The wrong ones to boot. You can check alternator output by jumpering from the field to the stator pins in the regulator plug (wiring harness). If you get 16.5 volts or above your alternator is good and you need to look at the battery (charge it overnight and then load test it or at least voltage test it, 12.6 volts and above is good. Then starter load test it by leaving the voltmeter on the battery and crank the starter for 10 seconds. The voltage should not drop below 10.5 volts while cranking.) and if the battery is good then replace the regulator.
I did troubleshoot it originally, the previous alternator didnt do anything and infact was making noise. The regulator has been replaced, I already did a load test on the battery, its 12.8Volts. I havent done it while cranking yet, ill try that in the morning
Post Fiend
Joined: Mar 2004
Posts: 6,056
Likes: 8
From: Union, Washington
Not much of a load test if you got 12.8 volts, sounds more like a static test which only tells you the battery will take a charge, not if it is any good. Cranking the starter on an FE will always get you into the 11 volt range, unless you have at least 2 batteries. Oh and under normal circumstances, if you change the alternator, you change the regulator because a bad alternator will screw up the regulator. So why didn't you mention you had troubleshot the problem?
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