98-f150 Re-charging Problem

I Forgot To Mention That If You Let The Truck Sit For 4 Or 5
Hours The Volt Gauge Will Work For Awhile.i Can Drive For
10 Miles Or So And All Of A Sudden The Gauge Will Start To Drop
This Is With No Excessories On.if You Turn On Excessories The
Needle Will Drop Faster.

I Forgot To Mention That If You Let The Truck Sit For 4 Or 5
Hours The Volt Gauge Will Work For Awhile.i Can Drive For
10 Miles Or So And All Of A Sudden The Gauge Will Start To Drop
This Is With No Excessories On.if You Turn On Excessories The
Needle Will Drop Faster.

Have you checked all the cable connections? You may have corrosion that is causing current to be slowed down after heat gets i the cables. Look at both ends of all cables. Let us know. Oh, yeah. If the problem is only after running a little while, the alternator may not have shown the problem when it was tested. it might need to be at operating temperature before it fails. Good luck.

Way2 Old Was Right On His Explanation Of What Was Wrong.

2 Fuses Were Bad.. One I Believe Was For The Voltage Regulator
20 Amp Under The Hood On Passenger Side Fire Wall Also The
Wire Was Melted Half Way Up The Harness To The Regulator.
The Other Fuse Was A 20amp Marked Alt Under The Hood Drivers
Side Near The Radiator.works Fine Now.....

Thanks Way2old