RX7 2RTR- 1308cc 1.3L Turbo FI (1989)
Fuel Pressure Regulator: Description and Operation
Secondary Fuel Rail (Delivery Pipe) And Injector
The fuel pressure regulator, built into the secondary fuel rail, maintains a constant pressure differential between intake manifold absolute pressure and
fuel system pressure.
Injector Duration Vs. Quantity @ Different Manifold Absolute Pressures
When manifold pressure is low (high vacuum), more fuel will spray from the injector than will at high manifold pressure (low vacuum) for the same
injection duration and fuel pressure. The fuel pressure regulator increases fuel system pressure as manifold absolute pressure increases, so that the
percent change in injection duration equals the percent change in the quantity of fuel injected.
Fuel Pressure Regulator
Control vacuum is applied to a diaphragm which operates a pressure valve. When the engine is under very light load, control vacuum is high, spring
pressure against the regulator valve is reduced and the fuel system is regulated at a lower pressure. When the engine is under heavy load (as in wide open
throttle operation), manifold absolute pressure increases reducing control vacuum. More spring pressure is applied to the valve and fuel system pressure
is increased by the same amount as manifold absolute pressure, maintaining a constant differential under changing engine loads.
The pressure regulator control (PRC) solenoid, is installed in the vacuum line to the fuel pressure regulator. During hot re-start, the ECU energizes the