1994 JEEP WRANGLER engine

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

(3) Lower the vehicle.
PARK NEUTRAL SWITCH
Refer to Group 21, Transmissions for park neutral
switch service.
POWER STEERING PRESSURE SWITCHÐ2.5L
ENGINE ONLY
The power steering pressure switch is installed in
the power steering high pressure hose (Figs. 11 or
12).
REMOVAL
(1) Disconnect the electrical connector from the
power steering pressure switch.
(2) Place a small container or shop towel beneath
the switch to collect any excess fluid.
(3) Remove the switch.
INSTALLATION
(1) Install the power steering switch.
(2) Connect the electrical connector to the switch.(3) Check power steering fluid and add as neces-
sary.
(4) Start the engine and again check power steer-
ing fluid. Add fluid if necessary.
POWERTRAIN CONTROL MODULE (PCM)
On XJ models, the PCM is located in the engine
compartment next to the air cleaner (Fig. 13). On YJ
models, the PCM is located in the engine compart-
ment behind the windshield washer fluid reservoir
(Fig. 14).
REMOVAL
(1) Disconnect the negative battery cable at the
battery.
(2) YJ Models Only: Remove the windshield
washer fluid tank.
(3) Loosen the 60-Way connector mounting bolt
(Figs. 13 or 14).
(4) Remove the electrical connector by pulling
straight back.
(5) Remove the three PCM mounting bolts.
(6) Remove PCM.
Fig. 11 Power Steering Pressure SwitchÐYJ Models
Fig. 12 Power Steering Pressure SwitchÐXJ Models
Fig. 13 PCM LocationÐXJ Models
Fig. 14 PCM LocationÐYJ Models
14 - 58 FUEL SYSTEMJ

INSTALLATION
(1) After the PCM electrical connector has been
separated from the PCM, inspect the pins for corro-
sion, being spread apart, bent or misaligned. Also in-
spect the pin heights in the connector. If the pin
heights are different, this would indicate a pin has
separated from the connector. Repair as necessary.
(2) Install PCM. Tighten three mounting bolts to 1
Nzm (9 in. lbs.) torque.
(3) Engage 60-way connector into PCM. Tighten
connector mounting bolt to 4 Nzm (35 in. lbs.) torque.
(4) YJ Models: Install windshield washer fluid
tank.
(5) Connect negative cable to battery.
QUICK-CONNECT FITTINGS
Refer to the Fuel Delivery System section of this
group for removal/installation procedures.
THROTTLE BODY
REMOVAL
(1) Disconnect the negative battery cable.
(2) Disconnect air cleaner hose from throttle body.
(3) Disconnect idle air control motor and throttle
position sensor wire connectors.
(4) Disconnect accelerator cable, throttle cable (au-
tomatic transmission) and speed control cable (if
equipped) from throttle arm (Fig. 15).
(5) Remove throttle body mounting bolts, throttle
body and gasket. Discard old gasket (Fig. 16).
INSTALLATION
(1) Install throttle body and new gasket. Tighten
throttle body mounting bolts to 12 Nzm (9 ft. lbs.)
torque.
(2) Connect idle air control motor and throttle po-
sition sensor wire connectors.
(3) Connect throttle linkage to throttle arm.CAUTION: When the automatic transmission throttle
cable is connected, it MUST be adjusted.
(4) If equipped with an automatic transmission,
connect and adjust the transmission line pressure ca-
ble. Refer to Group 21, Transmissions for adjustment
procedure.
(5) Install air cleaner hose to throttle body.
(6) Connect negative battery cable to battery.
THROTTLE POSITION SENSOR (TPS)
The TPS is mounted to the throttle body (Figs. 17
or 18).
REMOVAL
(1) Disconnect TPS electrical connector.
(2) Remove TPS mounting bolts.
(3) Remove TPS.
INSTALLATION
The throttle shaft end of the throttle body slides
into a socket in the TPS (Fig. 19). The TPS must be
installed so that it can be rotated a few degrees. (If
Fig. 16 Throttle
BodyÐRemoval/InstallationÐTypical
Fig. 17 TPS LocationÐ2.5L Engine
Fig. 15 Cables at Throttle Body
JFUEL SYSTEM 14 - 59

the sensor will not rotate, install the sensor with the
throttle shaft on the other side of the socket tangs).
The TPS will be under slight tension when rotated.
(1) Install the TPS and retaining bolts.
(2) Connect TPS electrical connector to TPS.
(3) Manually operate the throttle (by hand) to
check for any TPS binding before starting the en-
gine.
TORQUE CONVERTER CLUTCH RELAY
On YJ models, the TCC relay is located in the en-
gine compartment. It is attached to the cowl panel
with one bolt (Fig. 20). On XJ models, the TCC relay
is located in the power distribution center (PDC)
(Fig. 21). For location of this relay within the PDC,
refer to label on PDC cover.
VEHICLE SPEED SENSOR
The vehicle speed sensor (Fig. 22) is located on the
extension housing of the transmission on 2WD mod-
els. It is located on the transfer case on 4WD models.
REMOVAL
(1) Raise and support vehicle.
(2) Disconnect the electrical connector from the
sensor.
(3) Remove the sensor mounting bolt (Fig. 23).
Fig. 18 TPS LocationÐ4.0L Engine
Fig. 19 Throttle Position SensorÐInstallation
Fig. 20 TCC Relay LocationÐYJ Models
Fig. 21 Power Distribution CenterÐXJ Models
Fig. 22 Vehicle Speed Sensor LocationÐTypical
14 - 60 FUEL SYSTEMJ

SPECIFICATIONS
GENERAL INFORMATION
The following specifications are published from the
latest information available at the time of publica-
tion.If anything differs between the specifica-
tions found on the Vehicle Emission Control
Information (VECI) label and the following
specifications, use specifications on VECI label.
The VECI label is located in the engine compart-
ment.
FUEL TANK CAPACITIES
FUEL SYSTEM
TORQUE
14 - 62 FUEL SYSTEMJ

Fig. 22 Receiver DryerÐ4.0L Engine
24 - 32 HEATING AND AIR CONDITIONINGJ

Fig. 7 Air Cleaner VenturiÐTypical
Fig. 8 CCV SystemÐ2.5L EngineÐTypical
Fig. 9 CCV SystemÐ4.0L EngineÐTypical
JEMISSION CONTROL SYSTEMS 25 - 5

FUEL SYSTEM
CONTENTS
page page
ACCELERATOR PEDAL AND THROTTLE CABLE... 16
FUEL DELIVERY SYSTEM................. 2
FUEL TANKS........................... 12
GENERAL INFORMATION.................. 1
MULTI-PORT FUEL INJECTION (MFI)ÐCOMPO-
NENT DESCRIPTION/SYSTEM OPERATION . 17MULTI-PORT FUEL INJECTION (MFI)Ð
COMPONENT REMOVAL/INSTALLATION . . . 54
MULTI-PORT FUEL INJECTION (MFI)Ð
GENERAL DIAGNOSIS.................. 32
SPECIFICATIONS....................... 62
GENERAL INFORMATION
Throughout this group, references are made to par-
ticular vehicle models by alphabetical designation or
by the particular vehicle nameplate. A chart showing
a breakdown of the alphabetical designations is in-
cluded in the Introduction section at the beginning of
this manual.
TheFuel Systemconsists of: the fuel tank, an
electric (fuel tank mounted) fuel pump and a fuel fil-
ter. It also consists of fuel tubes/lines/hoses, vacuum
hoses, throttle body and fuel injectors.
TheFuel Delivery Systemconsists of: the electric
fuel pump, fuel filter, fuel tubes/lines/hoses, fuel rail,
fuel injectors and fuel pressure regulator.
AFuel Return Systemis used on all vehicles.
The system consists of: the fuel tubes/lines/hoses that
route fuel back to the fuel tank.
TheFuel Tank Assemblyconsists of: the fuel
tank, filler tube, fuel gauge sending unit/electric fuel
pump module, a pressure relief/rollover valve and a
pressure-vacuum filler cap.
Also to be considered part of the fuel system is the
Evaporation Control System.This is designed to
reduce the emission of fuel vapors into the atmo-
sphere. The description and function of the Evapora-
tive Control System is found in Group 25, Emission
Control Systems.
FUEL USAGE STATEMENT
Your vehicle was designed to meet all emission reg-
ulations and provide excellent fuel economy using
high quality unleaded gasoline. Only use unleaded
gasolines having a minimum posted octane of 87.
If your vehicle develops occasional light spark
knock (ping) at low engine speeds, this is not harm-
ful. However,continued heavy knock at high
speeds can cause damage and should be re-
ported to your dealer immediately.Engine dam-age as a result of heavy knock operation may not be
covered by the new vehicle warranty.
In addition to using unleaded gasoline with the
proper octane rating,those that contain deter-
gents, corrosion and stability additives are rec-
ommended.Using gasolines that have these
additives will help improve fuel economy, reduce
emissions and maintain vehicle performance. Gener-
ally, premium unleaded gasolines contain more addi-
tive than regular unleaded gasolines.
Poor quality gasolinecan cause problems such
as hard starting, stalling and stumble. If you experi-
ence these problems, use another brand of gasoline
before considering service for the vehicle.
GASOLINE/OXYGENATE BLENDS
Some fuel suppliers blend unleaded gasoline with
materials that contain oxygen such as alcohol, MTBE
and ETBE. The type and amount of oxygenate used
in the blend is important. The following are generally
used in gasoline blends:
ETHANOL
Ethanol (Ethyl or Grain Alcohol) properly blended,
is used as a mixture of 10 percent ethanol and 90
percent gasoline.Gasoline with ethanol may be
used in your vehicle.
METHANOL
CAUTION: DO NOT USE GASOLINES CONTAINING
METHANOL.Use of methanol/gasoline blends may re-
sult in starting and driveability problems. In addition,
damage may be done to critical fuel system compo-
nents.
Methanol (Methyl or Wood Alcohol) is used in a va-
riety of concentrations blended with unleaded gaso-
JFUEL SYSTEM 14 - 1