Big Blue24

I tried doubling up the spring... I put a ball point pen spring inside the Holley Blue spring, this resulted in 43psi as I recall. Next I tried stretching the Holley spring and running it by itself. This resulted in 16 psi. A month later I went back in there and stretched the spring some more, now I get 18 psi at idle which is perfect in my opinion. This spring controls an internal bypass piston, the more spring pressure, the more fuel pressure required before the internal bypass piston moves and allows fuel to internally bypass.
And no, you can't adjust this spring by pulling the bottom bolts, you must remove the large flat head screw on the side of the pump. Be careful as the spring and piston will come out as soon as you remove the screw. Be sure to pinch the fuel lines on both sides of the pump or you will pour some fuel on yourself. You can plug the hole with a finger while you stretch the spring and quickly reinstall...don't ask me how I know!

Yes JLent, I did have fuel pressure problems due to that pesky internal brass screen. Mine was half plugged up with black particles. I removed the four bottom bolts and pulled the screen.

Number47

funny i find this post after running my holley for 4 months now and it doent hold pressure steady anymore. it kinda fluctuates

Big Blue24

Check that brass screen, I bet it's full of junk! Also stretch the spring a little. My Holley has been on for 18 months now, still going strong ever since i removed the screen.