battery drain

[longsix]

hey guys,
on my ,86 f150, 4.9l, the battery drains over a few days , when not in use.
i changed the altenator, checked voltage, engine running(12.3v).
recharged battery over night ,checked voltage(12.8v).
cranked truck, checked voltage(12.4).
new alt. has the plug built in, so i checked all connections, they seem ok.
what could i have overlooked?
thanks in adv....longsix

[Gary Lewis]

Your voltage should be 14.0 or more when running, so if it is 12.3 or 12.4 your alternator isn't working.

By "has the plug built in" do you mean it doesn't have a regulator on the fender?  If so it is the 2G alternator and you may have a wiring problem.  You might want to read this TSB from Ford on it and check your wiring: http://www.garysgaragemahal.com/96-21-04-2g-alternator-repair.html.

[Steve83]

Post several pics of the alt, its wiring, the battery terminals, the starter relay (on the inner fender), the body/frame/engine ground points...  Read this caption & follow the link for instructions on embedding pics in your posts: