mattB52

I have an '06 silverado 4X4 with 5.3 V8. I am having problems with is starting. It turns over fine and firest atleast a couple times but will not start. I just got the truck and have had no issues. It was running fine then I turned off the ignition for about 5 min went to start it and it wouldnt. MY gas light had come on prior to that so I thought I may have run out of gas, I have put aver 6 gal in it and still am having problems. I tried puring the air out of the fuel system at the air valve on the fuel rail on the engine. I have also tapped and shaken lines to see if its clogged. I thought about changing the fuel filter but it is built into the fuel pump which is in tank and costs about $330. I was thinking about changing the pressure regulator since it is an easy $40 change. Any ideas?