My grandfathers 97 sierra won't start. It will sit there and turn over he cant tell if its getting fire when it is turning over or not. He has replaced the fuel filter so far. We can not think of what else it could be without going into major disassembley. What would be yall suggestion as to what could be wrong.

 

put your head near the gas tank and have him turn the ignition on, if u dont hear a buzz or whine, the fuel pump is shot, common thing with these trucks

 

To check and see if the truck is getting fire you can pull each spark plug out one at a time and put it back in the boot then hold the tip of the spark plug close to something metal and turn the ignition over and look for a spark jumping from the plug to the metal object you are holding it close to and if you dont see a spark it means no fire

 

Most likely your fuel pump.
I had a 98 Silverado and I changed the pump out 3 times.
The most common problem is if you run the trucks tank to empty, or anywhere les than a quarter of a tank too often, it usually messes up your pump.
I was 17 when I had mine, so I didnt have a lot of gas money, I would usually put $20 in the tank, which is about a quarter of a tank, and run it close to empty, then put more in it. Try filling the tank up and running the gas down to 1/4 tank then fill it up, dont let it run lower than a quarter tank too often.