Jeep 2002 WJ - Fuel Pressure Solenoid Description; Operation; Removal

FUEL PRESSURE SOLENOID
DESCRIPTION
The fuel pressure solenoid is attached to the rear
of the fuel rail. The solenoid controls and maintains
the rail pressure constant along with a control cur-
rent transmitted by the engine control module (ECM)
(Fig. 10).
OPERATION
High pressure which is present in the fuel rail
flows to the ball seat of the solenoid (Fig. 11). The
specified pressure required by the system is built up
in the rail by the fuel pressure solenoid building up a
magnetic force which corresponds to this specific
pressure by means of a control current from the elec-
tronic control module (ECM) (Fig. 11). This magnetic
force equals a certain outlet cross section at the ball
seat of the solenoid. The rail pressure is altered as a
result of the quantity of fuel which flows off (Fig. 11).
The current fuel pressure is signaled by the fuel
pressure sensor to the engine control module (ECM).
The controlled fuel flows back along the return fuel
line, into the tank.
In a de-energized state, the fuel pressure solenoid
is closed as the spring force presses the ball into the
ball seat (Fig. 11). When driving, the fuel pressure
solenoid is constantly open (Fig. 11). When engine is
started, the fuel pressure solenoid is held closed by
magnetic force (Fig. 11). When driving, the pressure
of the fluid counteracts the magnetic force of the coil
and the slight spring force (Fig. 11).
REMOVAL
WARNING: NO SPARKS, OPEN FLAMES OR SMOK-
ING. RISK OF POISONING FROM INHALING AND
SWALLOWING FUEL. RISK OF INJURY TO EYES
AND SKIN FROM CONTACT WITH FUEL. POUR
FUELS ONLY INTO SUITABLE AND APPROPRI-
ATELY MARKED CONTAINERS. WEAR PROTECTIVE
CLOTHING.
(1) Disconnect negative battery cable.
(2) Remove engine cover (Refer to 9 - ENGINE -
REMOVAL).
Fig. 9 MAF SENSOR LOCATION
1 - TURBOCHARGER
2 - MAF SENSOR
3 - AIR CLEANER HOUSING
4 - MAF SENSOR ELECTRICAL CONNECTOR
Fig. 10 FUEL PRESSURE SOLENOID
1 - INJECTION LINES
2 - FUEL RAIL
3 - FUEL RETURN LINE
4 - FUEL PRESSURE SOLENOID
5 - OIL LINE
6 - SEALS
7 - FUEL RETURN LINE AT COOLER
8 - HIGH PRESSURE FUEL LINE TO FUEL RAIL
9 - FUEL LINE BRACKET
10 - FUEL PRESSURE SENSOR
WG FUEL INJECTION 14a - 9
MANIFOLD AIR FLOW (MAF) SENSOR (Continued)