I let my 1988 IROC 5.7 V8 sit for about six months. I went to go start it and the battery was dead. I put a new battery in and it would crank, but wouldn't start. I put some fuel in the carb and it started right up but died after a few seconds. I took off the fuel line after the fuel filter to see if it was getting fuel and I was. I tried to start it with the line off and lots of fuel came through the line. I then removed the fuel lines in the engine compartment (see photo below) then turned the key to on and then tried to start it, lots of fuel came out of the upper fuel line but no fuel came out of the lower line.
Any ideas what the issue could be?