I think I know the answer to this, but I will ask anyway.

So I have my 440 in my GTX and wanted to get the motor running, so I ran the fuel line from the tank to the fuel pump, then pump to the carb. The return line was left open (this was a temporary thing).

I am unable to keep fuel pressure to the carb and I am thinking that this is due to the return line left open. Does this make sense or am I way off?

Also, does everyone run with the fuel vapor separator or have you removed it?