MTVR - 12/27/2023 13:59 I wanted to make sure I'm measuring fuel pressure and not air pressure inside the fuel system, so I loosened the bleed bolt on the top of the secondary fuel filter housing (the boss that says "BLEED" on the side) a couple of turns like it says to do in the Cat manual I found online, cranked it over for a few seconds, and I'm immediately getting fuel coming out, so there is fuel in the system, and it's as bled as I can bleed it without it running. I tightened the bleeder bolt back down afterwards. I disconnected the fuel return line at the tank, pointed it at a drain pan, and pumped the hand primer pump on the side of the secondary fuel filter base. After about a half-dozen pumps, I hear a metallic click inside the secondary fuel filter housing, and fuel runs out the return hose. I'm assuming the click is the fuel return check valve still/again. And the fuel pressure test gauge never moves off zero when I'm using the hand primer pump. I got fuel running out the return hose when cranking. The needle slowly rises to 60 psi and then bounces back and forth between 30 psi and 60 psi, with fuel running out the return hose. I am stumped...