Jeep Cherokee 1988 Quick Start Manual page 5

fuel return line. The regulator is not controlled by the ECU. The
regulator's spring chamber is vented to the same pressure as the tip
of the injector.
Fig. 3: Cross Section View of Fuel Pressure Regulator
Since fuel pressure at the injector is kept constant, the
volume of fuel injected is dependent only on the length of time that
the injector is energized. The injection time duration is based on
engine operating conditions, which are provided to the ECU by the