'91 F-150/Manual trans/IL 6/4.9L...hang on to your hats

I had a check engine light running rough, pulled the truck into the driveway (from 40ft away). I disconnected the battery cables to see if the computer would reset long enough to take it to Auto Zone to see what I needed for the check engine light.

Came back ~10mins and reconnected the battery...it sparked hard, then stopped. I put the key in, realized I had no power. I checked the battery (5yrs old) and it was completely dead and would not take a charge.

I took the bat to Auto Zone and got a new one and talked to them about it. "You shorted it out" How? I have no idea.

Then I put the new bat in and got some slight sparks. I attempted to start and it would lose all power. I disconneted the bat so I didn't fry another one.

My bud and I take the starter relay off and see a burn on the back..."that's it"...not...replaced it and got the same problem.

As soon as I turn the key "on" just prior to starting, it sparks and looses power.

So...it's the starter right? I disconnected the power to the starter then turned the truck on, radio, AC, everything worked. Dropped the starter replaced it and still broke.

These 2 USAF and Marine Corps aviators proudly admit we are completely stumped.

Any Ideas??????

Thanks, Joe

 

Is there any chance that your cable from the battery to the starter could be shorting out??