So I have a 1987 6.9. I tried to start it up in maybe 20-25 degree weather and it didn't want to start up. Have it a bit and tried again. Still did not want to start but this time when I turned the key off the starter kept going until it died completely. Now I have absolutely no power even with the battery's charged. And if I hook up a jump box to the battery while the terminals are connected it makes a buzzing noise that starts and stops. But it seems when the buzzing happens the jump box stops working. But when it stops the box fires back up. I'm getting ready to go check the fuses now. Maybe I'm just not thinking clearly because it's 4 AM?

 

disregard the power issue I had a bad connection. To the positive terminal, however when it connected it just decided to try to start on its own. The solenoid on the starter? Or maybe the relay? Not sure but killed the battery before I could get the terminal back off.

 

ford always used both solenoids to run the starter .. most likely the one of the fern is bad . test it and see . neither of them are vary expensive . but you have to pull the starter to replace its solenoid .