Not getting fuel to the rail even though I can hear the fuel pump prime when I turn the key

My truck had been sitting for about three years and I’m working on getting it back on the road. One of the things I did was I replaced the fuel filter. It had less than 1/4 tank of old gas in it that I diluted with fresh gas, octane booster, and fuel system cleaner. My engine cranks fine and will even start for a second or two with starter fluid. Thought maybe there’s a clog in the lines. I looked everywhere I could to find a kink in the lines somewhere but couldn’t. Fuel pump is getting juice to it because I can hear it prime. Just no gas getting to the fuel rail. Maybe a fuel pressure regulator? I hooked a siphoning pump to the Schrader valve on the rail to see if I could pump any fuel to get some flow to the rail, but it was dry as a bone. Does that mean the clog is on the other side of the filter towards the pump? Filter is brand new btw.