battery gauge
 

Does anybody have an idea why my battery gauge needle go up and down on my 86 GXL

Sounds like mabe a bad ground, or the amps coming out of your alternator.

I was just speaking with one of my friends and he says that ford has this problem frequently. There are springs inside the altrnator that keep pressure on magnets that read amps or something but they recieve voltage fom the armatre. Basically you need to rebuild or get another alternator. Try hiting it with a rubber mallet to see if it will correct at all.

bad ground

I am new at this rotary mechanics can you explain when you said bad Ground!! thanks

the ground wire tp the battery from the frame isnt getting a good connection

you can take a piece of good 6 or 8 guage wire and run it fron the rotor houseing to the negative battery post and it should fix it