So recently, my 91 Ford has been starting on the first try, over cold nights and multiple days. Now when I try to start it, the battery is completely dead. No cab lights or anything. If I jump it, it will start up fine and idle forever. When I shut the truck off and turn the key my battery is then completely dead. I replaced the battery already, need help thanks.

 

Get the alternator and the new battery tested.

 

Check the connectors at both ends of the wires. Shiny clean and tight. Ground is just as important as power.