[84LX89GT]

I put a 255 lph fuel pump in last week (preperation for my nitrous system i'm going to install) and when i checked fuel pressure i adjusted it down to 35 from 40 key on engine off....started it and it was up to 85 psi. I pulled off the return line and ran a hose from the fuel rail return (after the regulator) into a gas can. Pressure dropped to 35 psi with the engine running.
After reconnecting the return line, the pressure went back up to 85 psi.
I dropped the fuel tank and pulled off the return line at the pickup assembly to see if it was the pickup, and pressure remained at 85 psi with the fuel pickup out of the loop. I checked along the return line to see if it was pinched anywhere, but it wasn't. The line looks intact and i can't think of a cause for this except for the line being too small for pump.
Has anyone else run into this?
Am i going to have to route a larger return line to the tank?
Any suggestions on what i should do?
I'd like to do this on a budget beause i can't afford new fuel rails, and whole new fuel system with special pickup....i can save up, but it would be awhile for a fancy system.