Cat 3406E blew the fuel filter off

I was wrong about the pressure valve not being in the head. I swapped it out. My engine does cool the ecm with fuel. There is a line that coming from or going to the ecm on the bottom from the filter assembly and the other line is more at the top. I just don't know which way the fuel flows. If it comes from the filter housing to the ecm and out the top, where does it go? I couldn't blow any air through that line,

 

I have that new line but what a pain to try and get it loose on the top. Can't get a wrench in between the head and A/C bracket to save my soul. And it is rusted badly. I'm presuming if nothing comes out the hose at the junction block, I found my block?