Truck not cranking

I have an 1987 Ford F-150 4.9L 2WD w/Manual Tranmission.

I've just replaced the battery, solenoid, and starter.

The truck won't try to crank over. But if I crossover the solenoid manually it will.

For testing purposes, I also tried to bypass the neutral switch, thinking it was bad. It still wouldn't crank over.

I'm running out of ideas.

Please help!

Went through this on a 64 that I had (except that mine was an intermitant problem). After replacing the starter, solinoid, and ignition switch I found that where the neg- cable was grounded to the body (the only place the battery was grounded) wasn't making a good enough connection.

An easy way to test this is when it won't start hook one side of a pair of jumper cables from the neg side of the battry straight to the block (making sure you get good contact) and try it again. If it starts theres your problem.

On the 64 I got a cable from a friend that had clamp/anchor in the middle. I ran the anchor in the middle to the orgional spot on the body (after cleaning the rust from the mount spot w/ some sandpaper) and the end to the block on one of the starter ears. Never had a problem after that.

Check the fuse panel, If the fuse is good then your not grounded somewhere as truckdrivinfool stated. I'd just buy a new ground/neg-cable and replace it first. If it still won't start then check/replace the brain box. They are useualy located on the driver's side wheel fender. I'm not sure how to actually test one, I'd just replace it and see it that helps. There a dime a dozen in the bone yards. It's a silver square metal box with a plug wire and bolted down by two 3/8 bolt's.