Hi Snowman
Ok I try to comment...
The fuel pump and fuel pressure regulator work in concert to control fuel pressure supplied to the fuel injectors. At a given voltage, the fuel pump supplies fuel at a relatively constant rate to the pressure regulator. Unneeded fuel diverts back to the tank, to match fuel delivery to engine demand. Fuel flow from the pump varies strongly with voltage. If system voltage is low, the pump may not receive enough power to fully pressurize the system or supply the engine at high fuel demand conditions. Fuel pressure regulators are preset for a particular operating pressure during assembly, and are not adjustable.
In most all return systems, the fuel pressure regulator contains a vacuum chamber that is connected to manifold vacuum and is separated from the fuel by a diaphragm and valve assembly. The diaphragm has fuel on one side and engine manifold pressure (vacuum) on the other.
Most fuel pressure regulators contain a calibrated spring located in the vaccum chamber side. Fuel pressure in the fuel rail is regulated by pressurized fuel from the pump acting on the fuel rail side of the regulator’s diaphragm, pushing against the spring pressure and manifold pressure (vacuum) on the other side. When the combined force of vacuum on one side plus pressurized fuel on the diaphragm gets high enough to overcome spring pressure, the relief valve orifice opens, reducing rail pressure slightly by bypassing a controlled amount of fuel to the fuel tank. When an injector opens, it causes a slight pressure drop in the rail. In return systems with a vacuum hose connected to the regulator, vacuum applied to the regulator keeps the pressure difference (pressure drop) constant between manifold absolute pressure and supplied fuel pressure.
So in another words, if you change the regulator ideally you should change to a bigger fuel pump.
However, there are always questions after questions... what if above is done but somehow the injectors are too small to allow bigger flow and so the pressurized fuel all gets return to the tank.
Maybe a way to overcome this problem is to tune your ECU. Advance the timing and prolong the injectors opening time to utilise the exccess fuel pressure.
Then once you reach this stage, you find that there is not enuf air. So how? Force induction time....
good one! so will the fuel regulator actually cure the drop of low end power for car that change their muffler to the free flow type??
Cheers!...
GONG XI FA CAI