96 Chevrolet blazer

This could be any number of issues, may need to get a new filter if it hasnt been done. The age of the truck plays a part. Could be debris in the fuel tank that is now clogging the filter. If it is fuel injection the injector may be clogged, could be you need more fuel in it. Make sure your fuel pump works by turning on your truck with out starting it. Turn the key on and listen for the pump to click on and run sounds like a low hum. If it works then try looking to see is fuel is making its way to your carb or injector, find your fuel line and remove it and turn on your key, be very careful and put the fuel line in a can so not to start a fire.if all of these are yes then you may have a electrical problem. Im not a mechanic im just giving you ideas that ive had to do in the past.

I put 5 gallons of gasoline in it. I can hear the fuel pump running when I turn the key on. I almost got it started when I put a little gas in the carburetor.