Exactly How Doe the Fuel Pressure Regulator Work?

[gselvo]

I just replaced my fuel pump assembly and took apart the old one. Problem was low fuel pressure - only 38 psi instead of the 55 psi required. Seems to have fixed the problem. Presumably low pressure was due either to the pump itself or to the regulator, both are in the assembly. The regulator does not appear to have any electrical connection so I figured I could just put an air hose on it, blow it up to 55 psi and watch it open, but this did not happen, even when it was up to over 100 psi. So, my guess is that injection spray is regulated by computer and pressure regulator is not. Different in some other systems. This is a closed system, all in the tank. Anyone know how the pressure regulator actually works in this system and why it would not blow open with high pressure air hose?

 

[joegr]

I don't know exactly which system you have. In general, returnless systems loosely regulate the fuel pressure by having a sensor and reading the pressure, and then based on that controlling how much power is applied to the fuel pump motor. Of course, I'm sure that is different with GDI, since there is also a high pressure mechanical pump.

 

[gselvo]

I don't know exactly which system you have. In general, returnless systems loosely regulate the fuel pressure by having a sensor and reading the pressure, and then based on that controlling how much power is applied to the fuel pump motor. Of course, I'm sure that is different with GDI, since there is also a high pressure mechanical pump.

The 4.6 motor 2009. But still there is a fuel pressure regulator that appears to have no electrical connection but it must do something, presumably purely mechanical

 

[joegr]

The 4.6 motor 2009. But still there is a fuel pressure regulator that appears to have no electrical connection but it must do something, presumably purely mechanical

I thought those were more like maximum pressure relief devices, but I don't really know.

 

[gselvo]

I thought those were more like maximum pressure relief devices, but I don't really know.

that occurred to me as well, but I put over 100 lb pressure on through my bike pump and it didn't oopen, maybe I need to go higher?