Is the return line banjo bolt also a pressure relief valve. Where I'm going with this is my pressure guage is connected to the fuel inlet line on the IP and I wonder what regulates fuel pressure that I see on my guage. I usually have 13-15 psi at idle and lately it has been 11-12. I also had a pressure problem last week where it would start at 12 psi and 30 secs later it would drop to 4 psi and you could hear the LP change to a higher pitch like it was cavitating,checked all from tank to IP and found no problem.:confused: