does anyone know what pressure the tj magna fuel system operates at. I think its about 40psi but im nt 100% sure.

Approximately 265 Kpa (38.43 psi) at curb idle.

Approximately 265 Kpa (38.43 psi) at curb idle.

thanks for your help.

so as the rpm get higher does that rise? so at like 3000rpm what would it be at approximatley?

Fuel pressure is dependent on manifold pressure, not RPM. (This is why there is a vacuum hose on the FPR)

Cheers
Heath Young

That it correct, but manifold pressure depends on RPM. When throtle buterfly is closed vacuum is greater than when it is partialy open. When fully open manifold pressure is the same or nearly the same as atmosferic pressure. Higher the RPM lower the vacuum.
On magna fuel pressure regulator has 329 Kpa (47.71 psi). I assume it is a maximum pressure at which it operates. As the RPM goes up the fuel pressure goes up too.
What fuel pressure at 3000 RPM? I would not have a clue. :confused:

fuel system operating pressure 270kpa with vac. hose connected. 330-350kpa with hose disconnected

That it correct, but manifold pressure depends on RPM.

WOT is WOT mate. With a 55mm hole to let air in, even at 8000rpm, the vacuum within the manifold is negledgable.

Fuel pressure is a function of MAP and MAP only.

Fuel pressure is a function of MAP and MAP only.


Fuel is sent under pressure from the fuel tank by the fuel pump, with the pressure being regulated by the fuel pressure regulator.
The fuel is maintained at a constant pressure, relative to variances in manifold vacuum, by the fuel pressure regulator.
Excess fuel is returned to the fuel tank via the fuel return line.