how do i tell if fuel pump is bad

2000 blazer just shut off while driving then would not start again. this also happened about a month ago but started right up. I don't seem to hear the fuel pump go on.At first i did but now i don't. I hate to have my brother change the fuel pump and it be something else. How hard is it to change the pump? Also the fuel guage doesn't read properly after 1/2 a tank once it showed half a tank then all,of a sudden the low fuel light went on. I just bought the suv a month ago 103,000 miles. Other than this it was running like a champ and is in excellent condition,so i thought. Is it difficult to drop the tank on this vehicle? My brother has done a fuel pump before but not on an suv.

A fuel pressure test gauge kit is available at Harbor Freight and most chain type auto parts stores. An old Freon 12 gauge kit has the right screw on valve too if you happen to own one.
Here's the test port.

http://i131.photobucket.com/albums/p288/Clunk_/Image026.jpg

You might check the fuel pump relay, my '97 had them in the glove box....swap it with one of the other relays.