No start but have juice. need advice

[farfromhome]

TRuck wont start.I tried hooking up a tach but I think that caused the problem. I have about 12 volts in the battery,lights and wipers work.Tried to jump it, battery was getting 14+ volts when the jumper cables were hooked up but still wouldn't start. Checked all connections at battery and the conection at the ignition switch are tight.So I believe my starting circuit is faulty,isn't there a inline fuse in the harness? How do I go about tracking down the problem? Anybody have a problem like this before any help would be greatly appreciated.

Heres a little story about always disconnecting the ground cable before you unhook the starter.I didn't do it and I'm undoing the wiring on the starter to check the connection while under the truck and the ratchet handle hits the trans cooler line sparks start flying,I say "Oh @#$%" ratchet handle welds itself to the cooler line,sparks continue to fly,I smack the handle off the line,ratchet decides to take a chunk of the line with it and cooler line starts to drain tranny fluid.Awesome,I laugh and call myself a dumba$$ and go order a new line.One step forward two steps back.