S15/T15 2WD Jimmy V6-262 4.3L VIN W CPI (1993)
Fuel Pressure Regulator: Description and Operation
The Central Multiport Fuel Injector (CMFI) assembly has a low gain fuel pressure regulator to maintain pressure at the fuel injector through a range of
fuel recirculation rates from the in-tank fuel pump. With the ignition "ON" and engine "OFF," fuel pressure at the pressure test connection should be
380-420 kPa (55-61 psi) for 2 seconds. Fuel enters the fuel meter body through the inlet and flows into the injector cavity. When the Powertrain Control
Module (PCM) de-energizes the injector solenoid, fuel is recirculated through the pressure regulator. Fuel pressure applied to the regulator diaphragm
acts against the spring force and opens the valve from its seat. This allows fuel to flow through the fuel meter body outlet and back to the fuel tank via
the fuel return line. When the PCM energizes the injector solenoid, the armature lifts off the six fuel tube seats, delivers fuel through the fuel meter body
and out to the six poppet nozzles. The reduction in fuel recirculation reduces pressure on the regulator diaphragm and the spring force closes the valve
toward its seat until pressure is regained.