Fuel Problem

I have a 1989 gmc c1500 2WD Pickup,5.7Lt with 185K miles.The other day I had to tow my truck home because it would not crank back up. It appears to be a fuel problem. I can pour a little fuel into the Throttle body and it will crank,then die when the fuel runs out. I replaced the fuel pump in the tank. I checked the ecm fuse and injector fuse and they are ok. I have voltage at the fuel pump and voltage at the injectors. I turn the key to on position and put my ear to the gas cap and can hear something like the pump for about 2-3 seconds. What else can I check?