OK, here's my problem, 2003 s2000 sat over a year and half with out hardly any fuel, got the car running put on dyno and ran up to 10 psi boost, then started losing fuel pressure, mechanic sais it needs a fuel pump, drove it home with no problems, changed the fuel pump and pressure regulator and hard wired the pump with 12ga wire. Fuel pressure at 45 lbs at idle, when I give it gas pressure drops to 20 lbs voltage stays at 13.5 with no voltage drop, could the fuel pump housing be leaking, running out of things to change also took the fuel cap off. Thanks for any help

 

Where are you measuring the voltage? You want to check as close to the pump as possible.

 

The wire coming out of the relay hard wired to the pump and ground, just changed the wiring to 12 GA to see if that was the problem also tried 3 different fuel pumps and tried clamping the return line fuel pressure goes up at idle but whei I give it gas still drops to 20 psi and no leaks any where outside of tank, also it has SOS upgrade wire kit so relay is about 18" inches from pump plug