i have a 2002 blazer 4.3 vortec has new battery and just replaced the starter motor will not turn over when you try to turn it over it just clicks once like its throwing the starter up but not turning thats the same thing it did before i put a new starter in it. I took the battery to advance had it tested and charged im lost any ideas would be greatly appreciated thasnks

 

Are your battery terminals clean? The next thing would be to check the fusible link between the starter and the battery.

 

There are only a handfull of things that can cause this problem.......
1. The battery doesn't have enough cranking Amps
2. The Starter is bad
those 2 are very unlikely based on your post so I'd check these things
1. There is high resistance on the battery positive, or ground cable. IE.. corrosion under the plastic covers at the battery, or a loose connection at the starter (again unlikely with a new starter) or the ground cable on the front of the engine.
2. The starter isn't grounded very well to the engine block..(VERY unlikely)
3. The engine is seized up.
4.The engine is Hydrolocked.
Like I said there isn't much that can cause a "no crank" condition. You have already verified the integrity of Many components such as the ignition switch and the ignition wiring, because the starter does click when you try to start it. So it has to be one of those things listed above....If I think of any other POSSIBLE causes I'll post up, but I think that's it.

EDIT! Whoops, just thought of another cause...take the drive belt off and see if it cranks over then. You could have a belt-driven accessory siezed up and keeping it from cranking....not very common, but I have seen it happen.