Charging Problems 7.3 IDI
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Charging Problems 7.3 IDI
I have a 94 F-350 SuperDuty with a Versalift /utility body. Just purchased it last week. Runs great, has 106K miles on it.
Last night I was gonna take it out to show a friend the truck. On the way over I noticed that the Volt meter jumping back and forth. From about half to three quarters. It was like a steady fluctuation. When rpm was over 1500 the battery light would then start to fluctuate on and off just like the guage. Turned on the lights and the fluctuation became faster. The more accesories I turned on, the faster the fluctuation would become. However with the accessories on and the rpm up, the battery light would go off. Turned off the accessories while the rpm was up and the battery light then would flicker on and off.
I put a voltmeter directly on the battery and it would jump from 13.8 to 14.9 volts. It is a digital meter so it was hard getting true measurements.
This morning I started it up and did the same thing. Drove it to a shop to have a test performed on the charging system. However a couple of miles from the shop, the guage stopped its fluctuating. They performed the test and said everything checks out okay.
Drove it home and it was okay. This afternoon I drove it to my boat docks and it started up again. It continued to do this for about 35 miles and then it stopped.
The alternator looks as if it was changed recently. Case is clean, windings have no dirt on them, plus tool marks on the bolts.
All connections on batteries/alternator are spotless. Been cleaned 3 different times.
Any ideas on what to do? Thanks... D-N-B
Last night I was gonna take it out to show a friend the truck. On the way over I noticed that the Volt meter jumping back and forth. From about half to three quarters. It was like a steady fluctuation. When rpm was over 1500 the battery light would then start to fluctuate on and off just like the guage. Turned on the lights and the fluctuation became faster. The more accesories I turned on, the faster the fluctuation would become. However with the accessories on and the rpm up, the battery light would go off. Turned off the accessories while the rpm was up and the battery light then would flicker on and off.
I put a voltmeter directly on the battery and it would jump from 13.8 to 14.9 volts. It is a digital meter so it was hard getting true measurements.
This morning I started it up and did the same thing. Drove it to a shop to have a test performed on the charging system. However a couple of miles from the shop, the guage stopped its fluctuating. They performed the test and said everything checks out okay.
Drove it home and it was okay. This afternoon I drove it to my boat docks and it started up again. It continued to do this for about 35 miles and then it stopped.
The alternator looks as if it was changed recently. Case is clean, windings have no dirt on them, plus tool marks on the bolts.
All connections on batteries/alternator are spotless. Been cleaned 3 different times.
Any ideas on what to do? Thanks... D-N-B
Posting Guru
Joined: Jan 2000
Posts: 1,899
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From: Cullman Alabama
Your alternator is going. I've put five of them on my truck in the last seven years. I got one from NAPA that was guarenteed for a year, and they have replaced all five of them, because only a couple of them lasted for more than a year. Your batteries will go next if you dont change that alternator. You can do it in NAPA's parking lot in less than 15 minutes.
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Freshman User
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That was my thought to. It seems if I leave the lights on for awhile to drain down the batteries some, it does not fluctuate the voltage. It only does it when they are fully charged. Probably a diode breaking down in the rectifier. I had a Mopar that I could change the diode plates. Is Ford alternators the same way? Can they be rebuilt easily? Thanks.....D-n-B
