Is it hard to change the fuel pump in a 1993 chevy lumina van?

It's not that hard to change , with proper tools and instructions, I would recommend to visit local automotive store and buy the repair book for your vehicle. I would check the book before buying to makesure it covers your topic of intrest, then check which tool it needs and purchase that as well.

Changing the fuel pump is best done when tank is near empty.

However how do you know that Fuel pump is not working correctly, there is as fuel pump relay as well and fuse, have you check that ?
Is it hard to change the fuel pump in a 1993 chevy lumina van?
if you can get the vehicle up in the air enough to get the tank down. you have to make sure the you dont twist any of the lines off. make sure and clean off the top of the tank before changing the pump, you dont want any dirt and debris to get in the tank.
Is it hard to change the fuel pump in a 1993 chevy lumina van?
This could be caused by several other things and is probably not the FP.If your fuel pump goes your van will not start period. It sounds like an electrical problem.

Your best bet is to have an engine analysis done at your local Advance Auto or Pep Boys, that way you don't waste time and money.