warning JEEP WRANGLER 1994 Owner's Guide

REMOVALÐYJ MODELS
WARNING: EXTINGUISH ALL TOBACCO SMOKING
PRODUCTS BEFORE SERVICING THE FUEL SYS-
TEM. KEEP OPEN FLAME AWAY FROM FUEL SYS-
TEM COMPONENTS.
(1) Disconnect negative battery cable.
(2) Remove the fuel filler cap. Using an approved por-
table gasoline siphon/storage tank, drain fuel tank.
(3) Raise and support vehicle.
(4) Using a small straight blade screwdriver, pull
back the stems of the push clips that secure the fuel
filler neck shroud (located at bottom of left rear
wheel well) in place (Fig. 4). This unlocks the push
clip allowing them to be removed by pulling assem-
bly out of shroud. Remove shroud.
(5) Disconnect fuel fill hose and fill vent hose from
filler neck (Fig. 5).
WARNING: WRAP SHOP TOWELS AROUND FUEL
HOSES TO ABSORB ANY FUEL SPILLAGE DURING
FUEL TANK REMOVAL.(6) Disconnect fuel tank vent hose from vent tube.
Disconnect fuel supply and return hoses from tubes
(Fig. 6).
The fuel tank and skid plate are removed as an as-
sembly.
(7) Centrally position a transmission jack under
skid plate/fuel tank assembly.
(8) Remove skid plate/fuel tank assembly mount-
ing nuts (Fig. 7).Do not loosen tank strap nuts.
(9) Lower the skid plate/fuel tank assembly
slightly and disconnect the gauge sender wire con-
nector.
(10) Lower the fuel tank on transmission jack.
(11) Remove tank strap nuts to remove tank from
skid plate.
Fig. 4 Fuel Filler Neck ShroudÐYJ Models
Fig. 5 Filler Neck HosesÐYJ Models
Fig. 6 Fuel Tank HosesÐYJ Models
Fig. 7 Fuel TankÐRemove/InstallÐYJ Models
14 - 14 FUEL SYSTEMJ

INSTALLATIONÐYJ MODELS
(1) Place tank into skid plate. Wrap straps around
tank with strap bolts inserted through holes in skid
plate. Tighten strap nuts to 7.3 Nzm (65 in. lbs.) torque.
(2) Raise skid plate/fuel tank until gauge sender wire
connector can be connected to harness connector.
(3) Finish raising skid plate/fuel tank assembly
into position. Tighten mounting nuts to 16 Nzm (12
ft. lbs.) torque. Remove transmission jack.
(4) Connect fuel fill hose and fill vent hose to filler
neck. Tighten hose clamps.
(5) Connect vent hose to vent tube.
(6) Connect fuel supply hose to the supply tube and
fuel return hose to return tube. Tighten hose clamps.
(7) Install fuel filler neck shroud with push clips.
(8) Lower vehicle.
(9) Fill fuel tank. Install filler cap.
(10) Connect negative battery cable to battery.
(11) Start vehicle and inspect for leaks.
FUEL GAUGE SENDING UNIT
The fuel gauge sending unit is attached to the fuel
pump module. Refer to Fuel Pump Module in the
Fuel Delivery System section of this group.
FUEL TANK PRESSURE RELIEF/ROLLOVER VALVE
The fuel tank is equipped with a pressure relief/
rollover valve (Fig. 8). The dual function valve will
relieve fuel tank pressure and prevent fuel flow
through the fuel tank vent tubes in the event of ac-
cidental vehicle rollover.
The valve consists of a plunger, spring and orifice/
guide plate (Fig. 9). The valve is normally open allowing
fuel vapor to vent to the EVAP canister. Here it is
stored until it can be consumed by the engine (undercontrolled conditions). The plunger seats in the guide
plate at the orifice preventing liquid fuel from reaching
the EVAP canister. This is done if bottom of plunger is
contacted by fuel sloshing in tank when vehicle is cor-
nering.
In the event of accidental vehicle rollover, the valve
is inverted. In this position the plunger is forced
against the guide plate and raw fuel is prevented
from flowing through the valve orifice into the fuel
tank vent tube.
REMOVAL
WARNING: THE FUEL SYSTEM IS UNDER A CON-
STANT PRESSURE (EVEN WITH THE ENGINE OFF).
BEFORE SERVICING THE PRESSURE RELIEF/
ROLLOVER VALVE, THE FUEL SYSTEM PRESSURE
MUST BE RELEASED. REFER TO THE FUEL PRES-
SURE RELEASE PROCEDURE IN THIS GROUP.
(1) Disconnect negative battery cable.
(2) Remove the fuel filler cap and drain fuel tank.
Refer to Fuel Tank Removal.
(3) Remove fuel tank. Refer to Fuel Tank Removal.
(4) The rollover valve is seated in a grommet. Re-
move by prying one side upward and then roll the
grommet out of tank (Fig. 8).
INSTALLATION
(1) Start one side of grommet into opening in fuel
tank. Using finger pressure only, press valve/grom-
met into place.
(2) Install fuel tank. Refer to Fuel Tank Installation.
(3) Fill fuel tank. Install fuel tank filler cap.
(4) Connect negative battery cable.
(5) Start vehicle and check for leaks.
Fig. 8 Valve LocationÐTypical
Fig. 9 Pressure Relief/Rollover Valve Operation
JFUEL SYSTEM 14 - 15

ing the IAC motor pintle in and out of the air control
passage. The IAC motor is positioned when the igni-
tion key is turned to the On position.
A (factory adjusted) set screw is used to mechani-
cally limit the position of the throttle body throttle
plate.Never attempt to adjust the engine idle
speed using this screw.All idle speed functions are
controlled by the PCM.
IGNITION COILÐPCM OUTPUT
System voltage is supplied to the ignition coil pos-
itive terminal. The powertrain control module (PCM)
operates the ignition coil.Base (initial) ignition
timing is not adjustable.The PCM adjusts ignition
timing to meet changing engine operating conditions.
The ignition coil is located near the ignition distrib-
utor (Fig. 22).
Refer to Group 8D, Ignition System for additional
information.
MALFUNCTION INDICATOR LAMPÐPCM OUTPUT
The Malfunction Indicator Lamp (formerly referred
to as the Check Engine Lamp) illuminates on the in-
strument panel each time the ignition key is turned
on. It will stay on for three seconds as a bulb test.
If the powertrain control module (PCM) receives an
incorrect signal, or no signal from certain sensors or
emission related systems, the lamp is turned on. This
is a warning that the PCM has recorded a system or
sensor malfunction. In some cases, when a problem is
declared, the PCM will go into a limp-in mode. This
is an attempt to keep the system operating. It signals
an immediate need for service.
The lamp can also be used to display a Diagnostic
Trouble Code (DTC). Cycle the ignition switch On-
Off-On-Off-On within three seconds and any codes
stored in the PCM memory will be displayed. This is
done in a series of flashes representing digits. Refer
to On-Board Diagnostics in the General Diagnosis
section of this group for more information.
RADIATOR FAN RELAYÐPCM OUTPUT
XJ MODELS ONLY
The electric radiator cooling fan used in XJ models
(equipped with 4.0L engine, heavy duty cooling
and/or air conditioning) is controlled by the power-
train control module (PCM) through radiator fan re-
lay. The relay is energized when coolant temperature
is above 103ÉC (217ÉF). It will then de-energize when
coolant temperature drops to 98ÉC (208ÉF). Refer to
Group 7, Cooling Systems for more information.
The relay is located in the power distribution cen-
ter (PDC) (Fig. 23).
The electric radiator cooling fan is not used on YJ
models.
SCI TRANSMITÐPCM OUTPUT
SCI Transmit is the serial data communication
transmit circuit for the DRB scan tool. The power-
train control module (PCM) transmits data to the
DRB through the SCI Transmit circuit.
SHIFT INDICATORÐPCM OUTPUT
Vehicles equipped with manual transmissions have
an Up-Shift indicator lamp. The lamp is controlled
by the powertrain control module (PCM). The lamp
illuminates on the instrument panel to indicate when
the driver should shift to the next highest gear for
best fuel economy. The PCM will turn the lamp OFF
after 3 to 5 seconds if the shift of gears is not per-
formed. The up-shift light will remain off until vehi-
cle stops accelerating and is brought back to range of
up-shift light operation. This will also happen if ve-
hicle is shifted into fifth gear.
The indicator lamp is normally illuminated when
the ignition switch is turned on and it is turned off
when the engine is started up. With the engine run-
ning, the lamp is turned on/off depending upon en-
gine speed and load.
Fig. 23 PDCÐXJ Models
Fig. 22 Ignition CoilÐTypical
14 - 26 FUEL SYSTEMJ

REMOVAL
(1) Disconnect the electrical connector from the
sensor.
(2) Remove the sensor from the intake manifold.
INSTALLATION
(1) Install the sensor into the intake manifold.
Tighten the sensor to 28 Nzm (20 ft. lbs.) torque.
(2) Connect the electrical connector to the sensor.
CRANKSHAFT POSITION SENSOR
For description, operation and removal/installation
procedures, refer to Group 8D, Ignition Systems in
this manual.
ENGINE COOLANT TEMPERATURE SENSOR
The coolant temperature sensor is installed in the
thermostat housing (Fig. 5).
REMOVAL
(1) Drain cooling system until the coolant level is
below the cylinder head. Observe theWARNINGSin
Group 7, Cooling.(2) Disconnect the coolant temperature sensor wire
connector.
(3) Remove the sensor from the thermostat hous-
ing (Fig. 5).
INSTALLATION
(1) Install coolant temperature sensor into the cyl-
inder block. Tighten to 28 Nzm (21 ft. lbs.) torque.
(2) Connect the wire connector.
(3) Fill the cooling system. Refer to Group 7, Cool-
ing System.
FUEL FILTER
Refer to the Fuel Delivery System section of this
group for removal/installation procedures.
FUEL INJECTOR
REMOVAL
(1) Remove the fuel rail. Refer to Fuel Rail Re-
moval in this section.
(2) Remove the clip(s) that retain the fuel injec-
tor(s) to the fuel rail (Fig. 6).
Fig. 3 Sensor LocationÐ2.5L Engine
Fig. 4 Sensor LocationÐ4.0L Engine
Fig. 5 Engine Coolant Temperature SensorÐTypical
Fig. 6 Injector Retaining Clips
JFUEL SYSTEM 14 - 55

INSTALLATION
(1) Install the fuel injector(s) into the fuel rail as-
sembly and install retaining clip(s).
(2) Install fuel rail. Refer to Fuel Rail Installation
in this section.
(3) Start engine and check for fuel leaks.
FUEL PUMP MODULE
Refer to the Fuel Delivery System section of this
group for removal/installation procedures.
FUEL PUMP RELAY
The Fuel Pump relay is located in the Power Dis-
tribution Center (PDC) (Figs. 1 or 2). For location of
this relay within the PDC, refer to label on PDC
cover.
FUEL RAIL ASSEMBLY
REMOVAL
WARNING: THE FUEL SYSTEM IS UNDER CON-
STANT FUEL PRESSURE (EVEN WITH THE ENGINE
OFF) OF APPROXIMATELY 131-269 KPA (19-39
PSI). THIS PRESSURE MUST BE RELEASED BE-
FORE SERVICING THE FUEL RAIL.
(1) Remove fuel tank filler tube cap.
(2) Disconnect the negative battery cable from bat-
tery.
(3) Perform the Fuel System Pressure Release Pro-
cedure as described in the Fuel Delivery System sec-
tion of this Group.
(4) Remove and numerically attach a tag (if fuel
injector is not already tagged), the injector harness
connectors. Do this at each injector (Fig. 7).
(5) Disconnect vacuum line from fuel pressure reg-
ulator (Fig. 7).
(6) Disconnect fuel supply line from fuel rail and
the fuel return line from fuel pressure regulator (Fig.7). Refer to Fuel Tubes/Lines/Hoses and Clamps, or
Quick-Connect Fittings. These can both be found in
the Fuel Delivery section of this group.
(7) Remove fuel rail mounting bolts.
On models with automatic transmissions, it may be
necessary to remove automatic transmission throttle
line pressure cable (and bracket). This will aid in fuel
rail assembly removal.
(8) Remove fuel rail by gently rocking until all the
fuel injectors are out of the intake manifold.
INSTALLATION
(1) Position tips of all fuel injectors into the corre-
sponding injector bore in the intake manifold. Seat
injectors into manifold.
(2) Tighten fuel rail mounting bolts to 27 Nzm (20
ft. lbs.) torque.
(3) Connect injector harness connectors to appro-
priate (tagged) injector.
(4) Connect both fuel lines to fuel rail.
(5) Connect vacuum supply line to fuel pressure
regulator.
(6) Install protective cap to pressure test port fit-
ting.
(7) Install fuel tank cap.
(8) Connect negative battery cable to battery.
(9) Start engine and check for fuel leaks.
FUEL SYSTEM PRESSURE RELEASE PROCEDURE
WARNING: THE FUEL SYSTEM IS UNDER A CON-
STANT PRESSURE (EVEN WITH THE ENGINE OFF)
OF APPROXIMATELY 100 KPA (14.5 PSI). BEFORE
SERVICING THE FUEL PUMP, FUEL LINES, FUEL
FILTER OR FUEL INJECTOR, THE FUEL SYSTEM
PRESSURE MUST BE RELEASED.
Refer to the Fuel Delivery System section of this
group. See Fuel Pressure Release procedure.
FUEL TANKS
Refer to the Fuel Tank section of this group for re-
moval/installation procedures.
FUEL TANK PRESSURE RELIEF/ROLLOVER VALVE
Refer to the Fuel Tank section of this group for re-
moval/installation procedures.
FUEL TUBES/LINES/HOSES AND CLAMPS
Refer to the Fuel Delivery System section of this
group for removal/installation procedures. Also refer
to Quick-Connect Fittings in the Fuel Delivery sec-
tion of this group.
IDLE AIR CONTROL (IAC) MOTOR
The IAC motor is mounted to the throttle body ad-
jacent to the throttle position sensor (Fig. 8).
Fig. 7 Fuel Injector HarnessÐTypical
14 - 56 FUEL SYSTEMJ

REMOVAL
(1) Disconnect the electrical connector from the
IAC motor.
(2) Remove IAC motor torx head mounting bolts.
(3) Remove IAC motor.
INSTALLATION
(1) Install IAC motor into throttle body and
tighten retaining bolts.
(2) Connect electrical connector to IAC motor.
IGNITION COIL
Refer to Group 8D, Ignition Systems for removal/
installation procedures.
INTAKE MANIFOLD
Refer to Group 11, Exhaust System and Intake
Manifold for removal/installation procedures.
MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR
The MAP sensor is located on the dash panel near
the rear of the engine cylinder head (valve) cover
(Fig. 9).
REMOVAL
(1) Disconnect the MAP sensor electrical connector
(Fig. 9).
(2) Disconnect the MAP sensor vacuum supply
hose (Fig. 9).
(3) Remove the MAP sensor mounting bolts and
remove MAP sensor.
INSTALLATION
(1) Install MAP sensor to dash panel and secure
with mounting bolts.
(2) Install the MAP sensor vacuum supply hose.
(3) Connect the MAP sensor electrical connector.
OXYGEN (O2S) SENSOR
The O2S sensor is installed in the exhaust down
pipe just below the exhaust manifold flange (Fig. 10).
REMOVAL
WARNING: THE EXHAUST MANIFOLD BECOMES
VERY HOT DURING ENGINE OPERATION. ALLOW
ENGINE TO COOL BEFORE REMOVING OXYGEN
SENSOR.
(1) Raise and support the vehicle.
(2) Separate the electrical connectors.
(3) Remove the O2S sensor from the exhaust man-
ifold. Snap-On oxygen sensor wrench (number YA
8875) may be used for removal and installation.
INSTALLATION
Threads of new factory oxygen sensors are coated
with anti-seize compound to aid in removal.
(1) Install the O2S sensor into the exhaust mani-
fold and tighten to 30 Nzm (22 ft. lbs.) torque.
(2) Connect the O2S sensor wire connector to the
main harness.
Fig. 8 Idle Air Control
MotorÐRemoval/InstallationÐTypical
Fig. 9 MAP SensorÐTypical
Fig. 10 Oxygen SensorÐTypical
JFUEL SYSTEM 14 - 57

Fig. 2 Lockplate Removal
Fig. 3 Turn/Hazard Switch And Dimmer Actuating
Arm Screws
JTURN SIGNALS AND HAZARD WARNING FLASHER 8J - 3

Fig. 5 PRNDL Cable Clip Removal/Installation
Fig. 6 Lower Steering Column
Fig. 7 Turn/Hazard Switch And Steering Column
Connectors
8J - 4 TURN SIGNALS AND HAZARD WARNING FLASHERJ

Fig. 9 Remove Plastic Harness Cover
JTURN SIGNALS AND HAZARD WARNING FLASHER 8J - 5

Fig. 1 Buzzer Module Connector Terminal
IdentificationÐPin Side
8U - 2 CHIME/BUZZER WARNING SYSTEMSJ