MSefi.com read only forum (Jan.15,2018)

just a quick question as i am fitting injection to a car that never had it before.
the fuel comes from the tank, to a filter then to the fuel pump. the fuel pump then feeds the fuel to th fuel rail.
from the fuel rail it then feeds an external fuel pressure regulator, the pressure regulator holds back the fuel till it reaches the pressure and releases excess back to the tank.
Hope i have go that bit right.
when the power is removed from the fuel pump is the pressure supposed to dissapear??? (my regulator has a gauge on it)
I was under the impression that the fuel should stay pressurised between the fuel pump and the pressure regulator when switched off?

thanks for your help

i am guessing fuel pump then as regulator is new, i suppose i could fit a 1 way valve inline after the fuel pump that way no fuel can find its way back through the pump

The fuel rail should hold significant pressure until the engine has cooled down to prevent a fire. This is the same reason a car's cooling system is held under pressure to prevent boiling. My 1990 VW has a sensor for temperature above the intake manifold and a sensor for fuel pressure on the rail. They are simple on/off switches that are wired to a couple relays. After the car is turned off: if the temperature is above a certain point and the pressure drops below a certain point, the relays are powered in such a way to turn the pump on.