I am having problems starting my 1996 ford f250 7.3. The battery drains dead when i disconnect and reconnect the terminals. The starter engages. when i hook up the battery terminals to the batteries, the starter engages and turns.If I hook up the battery charger with out taking off the cables, the charger needle jumps back and forth and clicks a lot. The ford has a new alternator as well as new batteries. There is a unit (mane a relay-not sure) on the passenger side under the hood that keeps clicking. What is this part called? Could this be the problem?

 

Clicking means that it is getting power on and off to its coil.

Sounds like you may have a bad starter relay or Ignition switch.

CAUTION:
Block the wheels and take it out of park and see if it still cranks when you re-hook the battery cables. Only touch for a moment as if the engine stars the truck could move.

If it does replace the starter relay.
If it does not crank then replace the Ignition switch or its plug.

 

OK, let me get this straight.

Batteries disconnected. Then you connect them and the starter spins. Right?

The thing on the finder with the big wires going to it (and some smaller wires) is the starter solenoid. It is just a relay (read: electrically-controlled switch) which takes a signal from the key, and then sends power to the starter.

Pull off any of the smaller wires to the solenoid which have slip-on connectors; don't mess with the ones which require a wrench to remove. Then, reconnect the batteries and see if the starter spins.

Roy

 

It is possible the starter solenoid is stuck in the closed position. The one on the fenderwell on the left side, disconnect the small wire, if it still cranks bang on the solenoid, if still cranking disconnect the bolted on wire going to the starter, if still cranking, check the solenoid on the starter, wires might be touching or that solenoid is stuck too. these trucks use 2 solenoids Dvaid7.3