I recently installed a fuel pressure regulator and a fuel pressure gauge on my fuel system. I am using a factory replacement fuel pump with the return line. When I first fire the engine when it has been sitting for a while the gauge reads at 6 psi. After it has warmed up it dropps to aorund 4.5 to 5 psi and can fluctuate to as low as about 3.5 at times, but returns to aruond 5 psi. I was wondering if this was because of the return line or not. What are the factory pumps rated for psi at and what do they normally idle at? What would some of the Holley mechanical fuel pumps read on a fuel pressure guage at idle?

Thanks

Or if you guys have any other suggestions on mechanical fuel pumps would be great.

Thanks. You guys are awsome.