I own a 86 f250 with 6.9, truck runs great. If I let set for 2 weeks, the 2 batteries will be so dead that the needle on the fuel gage wont move. I have a multi meter, how do I check for a short?
thanks nick c

 

If your multi meter does Amps, Set it up for the highest amps, then disconnect your positive battery cable, connect the red lead of your meter to the positive battery post, connect the black lead of your meter to the positive battery cable!

BE CAREFUL ensure nothing shorts out!

If you have a draw the meter will show ...
Start with your meter set on the highest amp settings and work down!
DO NOT try starting the motor or turn anything on that will out amp your meter, you will burn the fuse in your meter!

Now start pulling fuses checking the meter after each fuse ... If that doesn't find it, start unhooking electrical items one at a time watching the meter!

A good place to start unplugging is the Sound System if one has been installed!

DO NOT forget to change your meter back before any other use!

EDIT
Remember, it could be bad batteries losing their charge!
Have them load tested.

EDIT2
See red ...

-Enjoy
fh : )_~

 

Also remember the dome light goes on when you open the door to get to the fuse block...

 

should be less than 3 milliamps draw for memory's in radio