Wonder if anyone know what the pre 99 fuel pressure is around? (4.6 HSE)
I have read that you should restrict the return pipe but how much?
Anyone ever measured what pressure the pump is capable of? (Yes sure it differ how worn it is)
Reading RAVE the pre 99 has a regulator in fuel rail with return pipe to tank but the post 99 has a regulator built in the pump set at 3.5 bar and no return line.
Underneath is from RAVE:
Fuel pressure regulator - (up to 99MY only)
The fuel pressure regulator is a mechanical device
controlled by manifold depression and is mounted at
the rear of the engine in the fuel rail. The regulator
ensures that fuel pressure is maintained at a constant
pressure difference to that in the inlet manifold. As
manifold depression increases, the regulated fuel
pressure is reduced in direct proportion. When
pressure exceeds the regulator setting, excess fuel is
spill returned to the fuel tank swirl pot which contains
the fuel pick up strainer.
Failure of the regulator will result in a rich mixture at
idle but normal at full load, or a rich mixture resulting
in engine flooding, or a weak mixture. Although the
fault will not illuminate the MIL, faults caused by the
failure may be indicated.
Fuel injectors - from 99MY
There are eight fuel injectors, one per cylinder which
the ECM operates sequentially. All the injectors are
fed from a common fuel rail as part of the returnless
fuel system. Fuel pressure is maintained at a constant
3.5 bar (52 lbf.in2) by a regulator that is integral with
the fuel pump
I have read that you should restrict the return pipe but how much?
Anyone ever measured what pressure the pump is capable of? (Yes sure it differ how worn it is)
Reading RAVE the pre 99 has a regulator in fuel rail with return pipe to tank but the post 99 has a regulator built in the pump set at 3.5 bar and no return line.
Underneath is from RAVE:
Fuel pressure regulator - (up to 99MY only)
The fuel pressure regulator is a mechanical device
controlled by manifold depression and is mounted at
the rear of the engine in the fuel rail. The regulator
ensures that fuel pressure is maintained at a constant
pressure difference to that in the inlet manifold. As
manifold depression increases, the regulated fuel
pressure is reduced in direct proportion. When
pressure exceeds the regulator setting, excess fuel is
spill returned to the fuel tank swirl pot which contains
the fuel pick up strainer.
Failure of the regulator will result in a rich mixture at
idle but normal at full load, or a rich mixture resulting
in engine flooding, or a weak mixture. Although the
fault will not illuminate the MIL, faults caused by the
failure may be indicated.
Fuel injectors - from 99MY
There are eight fuel injectors, one per cylinder which
the ECM operates sequentially. All the injectors are
fed from a common fuel rail as part of the returnless
fuel system. Fuel pressure is maintained at a constant
3.5 bar (52 lbf.in2) by a regulator that is integral with
the fuel pump
