1995 JEEP YJ battery

FUEL DELIVERY SYSTEM
INDEX
page page
Fuel Filter................................ 9
Fuel Pressure Leak Down Test................ 8
Fuel Pressure Release Procedure.............. 6
Fuel Pump Capacity Test.................... 7
Fuel Pump Electrical Control.................. 5Fuel Pump Module......................... 3
Fuel System Pressure Test................... 6
Fuel Tubes/Lines/Hoses and Clamps............ 9
Quick-Connect Fittings..................... 10
FUEL PUMP MODULE
The fuel pump module is installed in the top of the
fuel tank. The fuel pump module contains the follow-
ing components:
²Electric fuel pump
²Fuel pump reservoir
²In-tank fuel filter
²Fuel gauge sending unit
²Fuel supply and return tube connections
The fuel pump used on all vehicles is a turbine
type pump. It is driven by a permanent magnet 12
volt electric motor that is immersed in the fuel tank.
The electrical pump is integral with the fuel sender
unit. The pump/sender assembly is installed inside
the fuel tank.
The fuel pump has a check valve at the outlet end
that consists of a ball held against a seat by force ap-
plied from a spring. When the pump is operating,
fuel pressure overcomes spring pressure and forces
the ball off its seat, allowing fuel to flow. When the
pump is not operating, spring pressure forces the ball
back against the seat preventing fuel backflow
through the pump.
Fuel system pressure is maintained at approxi-
mately 214 kPa (31 psi). This is when the pump is
operating and vacuum is supplied to the fuel pres-
sure regulator. If vacuum is not supplied to the pres-
sure regulator, fuel pressure will be approximately
55-69 kPa (8-10 psi) higher. This may be due to a
broken or clogged vacuum line. When the fuel pump
is not operating, fuel system pressure of 131-269 kPa
(19-39 psi) is maintained for approximately 2 to 6
hours. This is done by the fuel pump outlet check
valve and the vacuum assisted fuel pressure regula-
tor.
REMOVALÐXJ MODELS
The fuel pump/gauge sender unit assembly can be
removed from the fuel tank without removing the
tank from the vehicle.
WARNING: THE FUEL SYSTEM IS UNDER A CON-
STANT PRESSURE (EVEN WITH THE ENGINE OFF).
BEFORE SERVICING THE FUEL PUMP MODULE,
THE FUEL SYSTEM PRESSURE MUST BE RE-LEASED. REFER TO THE FUEL PRESSURE RE-
LEASE PROCEDURE IN THIS GROUP.
WARNING: EXTINGUISH ALL TOBACCO SMOKING
PRODUCTS BEFORE SERVICING THE FUEL SYS-
TEM. KEEP OPEN FLAME AWAY FROM FUEL SYS-
TEM COMPONENTS.
(1) Remove fuel filler cap. Perform the Fuel Pres-
sure Release Procedure as outlined in this group.
(2) Disconnect negative battery cable.
(3) Using an approved portable gasoline siphon/
storage tank, drain fuel tank until fuel level is below
one quarter (1/4) full.
(4) Raise and support vehicle.
WARNING: WRAP SHOP TOWELS AROUND FUEL
HOSES TO ABSORB ANY FUEL SPILLAGE DURING
FUEL TANK REMOVAL.
(5) Disconnect fuel vent supply and return tubes
from fittings on fuel pump module.
(6) Disconnect fuel pump module electrical harness
connector from main harness.
(7) Using a brass punch and hammer, remove fuel
pump module lock ring by carefully tapping it coun-
terclockwise (Fig. 1).
Fig. 1 Removing Lock RingÐXJ ModelsÐTypical
JFUEL DELIVERY SYSTEM 14 - 3

(8) Remove fuel pump module and O-ring seal.
Discard old O-ring and fuel pump module inlet filter.
DISASSEMBLYÐXJ MODELS
(1) Remove and discard fuel pump inlet filter.
The wire terminals to the fuel pump motor are dif-
ferent in size and cannot be connected to the wrong
terminal.
(2) Disconnect fuel pump terminal wires.
(3) Remove fuel pump outlet hose and clamp. Re-
place the hose if it shows any signs of fatigue or fail-
ure.
(4) Remove fuel pump top mounting bracket nut.
Remove fuel pump (Fig. 2).
ASSEMBLYÐXJ MODELS
Whenever the fuel pump is replaced, the fuel pump
inlet filter (sock) must also be replaced.
(1) Place fuel pump top mounting bracket over top
of pump.
(2) Position fuel pump into lower bracket. Slide
stud of top bracket through hole in fuel pump side
bracket. Tighten fuel pump top mounting nut.
(3) Install new fuel pump outlet hose. Secure with
new clamps.
(4) Connect wire terminals to motor.
(5) Install new fuel pump inlet filter.
INSTALLATIONÐXJ MODELS
Whenever the fuel pump is replaced, the fuel
pump inlet filter must also be replaced.
(1) Install new fuel pump inlet filter onto fuel
pump.(2) Install fuel pump module assembly and new O-
ring seal. The rubber stopper on the end of the fuel
return tube of the assembly must be inserted into the
cup in the fuel tank reservoir (Fig. 3).
(3) Using a brass punch and a hammer, install lock
ring. Carefully tap lock ring clockwise until it seats
against stop on fuel tank.
(4) Connect fuel supply and return hoses to fittings
on fuel pump module. Tighten hose clamps.
(5) Connect fuel pump module electrical harness
connector to main harness connector.
(6) Lower vehicle.
(7) Fill fuel tank. Install fuel tank cap.
(8) Connect negative battery cable.
(9) Start vehicle and inspect for leaks.
REMOVALÐYJ MODELS
The fuel tank must be removed to remove the fuel
pump module.
WARNING: THE FUEL SYSTEM IS UNDER A CON-
STANT PRESSURE (EVEN WITH THE ENGINE OFF).
BEFORE SERVICING THE FUEL PUMP MODULE,
THE FUEL SYSTEM PRESSURE MUST BE RE-
LEASED. REFER TO THE FUEL PRESSURE RE-
LEASE PROCEDURE IN THIS GROUP.
WARNING: EXTINGUISH ALL TOBACCO SMOKING
PRODUCTS BEFORE SERVICING THE FUEL SYS-
TEM. KEEP OPEN FLAME AWAY FROM FUEL SYS-
TEM COMPONENTS.
(1) Remove negative battery cable.
Fig. 2 Fuel Pump ModuleÐXJ ModelsÐ
Disassemble/Assemble
Fig. 3 Fuel Pump ModuleÐXJ ModelsÐInstallation
14 - 4 FUEL DELIVERY SYSTEMJ

(2) Remove fuel filler cap. Perform the Fuel Pres-
sure Release Procedure as outlined in this group.
(3) Remove fuel tank. Refer to Fuel Tank Remov-
alÐYJ Models.
(4) Remove fuel pump module assembly.
(5) Remove mounting screws. Lift assembly and
gasket out of fuel tank. Discard old gasket (Fig. 4).
(6) Remove and discard fuel pump inlet filter.
DISASSEMBLYÐYJ MODELS
(1) Remove and discard fuel pump inlet filter (Fig.
5).
The wire terminals to the fuel pump motor are dif-
ferent in size and cannot be connected to the wrong
terminal.
(2) Disconnect fuel pump terminal wires from
pump.
(3) Remove fuel pump outlet hose and clamp (Fig.
6). Replace the hose if it shows any signs of fatigue
or failure.(4) Remove fuel pump top mounting bracket nut
(Fig. 6). Remove fuel pump.
ASSEMBLYÐYJ MODELS
Whenever the fuel pump is replaced, the fuel pump
inlet filter (sock) must also be replaced.
(1) Place fuel pump top mounting bracket over top
of pump.
(2) Position fuel pump into lower bracket. Slide
stud of top bracket through hole in fuel pump side
bracket. Tighten fuel pump top mounting nut.
(3) Install new fuel pump outlet hose. Secure with
new clamps.
(4) Connect wire terminals to motor.
(5) Install new fuel pump inlet filter.
INSTALLATIONÐYJ MODELS
(1) Install a new fuel pump inlet filter.
(2) Install fuel pump module assembly with a new
gasket between the assembly and tank. Tighten
mounting screws to 2 Nzm (18 in. lbs.) torque.
(3) Install fuel tank. Refer to Fuel Tank Installa-
tionÐYJ Models.
(4) Fill fuel tank. Install fuel tank cap.
(5) Install negative battery cable.
(6) Start vehicle and check for leaks.
FUEL PUMP ELECTRICAL CONTROL
For an electrical operational description of the fuel
pump, refer to the MFI SystemÐComponent Descrip-
tion/System Operation section of this group. See Au-
tomatic Shutdown (ASD) RelayÐPCM Output.
For the 1995 model year, the ballast resistor and
ballast resistor bypass relay are no longer used to
control the fuel pump circuit.
Fig. 4 Fuel Pump ModuleÐRemove/InstallÐYJ
Models
Fig. 5 Fuel Pump ModuleÐYJ Models
Fig. 6 Fuel Pump Removal/InstallationÐYJ Models
JFUEL DELIVERY SYSTEM 14 - 5

FUEL PRESSURE RELEASE PROCEDURE
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 BEFORE
SERVICING ANY FUEL SUPPLY OR FUEL RETURN
SYSTEM COMPONENT.
(1) Disconnect negative battery cable.
(2) Remove fuel tank filler neck cap to release fuel
tank pressure.
WARNING: DO NOT ALLOW FUEL TO SPILL ONTO
THE ENGINE INTAKE OR EXHAUST MANIFOLDS.
PLACE SHOP TOWELS UNDER AND AROUND THE
PRESSURE PORT TO ABSORB FUEL WHEN THE
PRESSURE IS RELEASED FROM THE FUEL RAIL.
WARNING: WEAR PROPER EYE PROTECTION
WHEN RELEASING FUEL SYSTEM PRESSURE.
(3) Remove protective cap from pressure test port
on the fuel rail (Fig. 7).
(4) Obtain the fuel pressure gauge/hose assembly
from fuel pressure gauge tool set 5069. Remove the
gauge from the hose.
(5) Place one end of hose (gauge end) into an ap-
proved gasoline container.
(6) Place a shop towel under the test port.
(7) To release fuel pressure, screw the other end of
hose onto the fuel pressure test port.
(8) After fuel pressure has been released, remove
the hose from the test port.
(9) Install protective cap to fuel test port.
FUEL SYSTEM PRESSURE TEST
The fuel system is equipped with a vacuum as-
sisted fuel pressure regulator (Fig. 8). With engine atidle speed, system fuel pressure should be approxi-
mately 214 kPa (31 psi) with the vacuum line con-
nected to the regulator. With the vacuum line
disconnected from the regulator, fuel pressure should
be approximately 269 kPa (39 psi). This is 55-69 kPa
(8-10 psi) higher.
(1) Remove the protective cap at the fuel rail (Fig.
7). Connect the 0-414 kPa (0-60 psi) fuel pressure
gauge (from Gauge Set 5069) to test port pressure fit-
ting on fuel rail (Fig. 9).
(2) Note pressure gauge reading. Fuel pressure
should be approximately 214 kPa (31 psi) at idle.
(3) Disconnect vacuum line (hose) at fuel pressure
regulator (Fig. 8). Note gauge reading. With vacuum
line disconnected, fuel pressure should rise to ap-
proximately 269 kPa (39 psi).
Fuel pressure should be approximately 55-69 kPa
(8-10 psi) higher with vacuum line removed from reg-
ulator. If not, inspect pressure regulator vacuum line
for leaks, kinks or blockage. If vacuum line checks
Fig. 7 Pressure Test PortÐTypical
Fig. 8 Fuel Pressure RegulatorÐTypical
Fig. 9 Fuel Pressure Test ConnectionÐTypical
14 - 6 FUEL DELIVERY SYSTEMJ

codes are not displayed, the problem may be mechan-
ical rather than electronic.
FUEL FILTER
The fuel filter protects the fuel injectors and fuel
pressure regulator from dirt, water and other foreign
matter. The filter is located under the vehicle along
the frame rail (Figs. 13 or 14). Replace fuel filter at
intervals specified in the Lubrication and Mainte-
nance Schedule chart found in Group 0, Lubrication
and Maintenance.
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 BEFORE
SERVICING THE FUEL FILTER.
(1) Disconnect negative battery cable. Remove fuel
filler cap.
WARNING: FUEL PRESSURE MUST BE RELEASED
BEFORE DISCONNECTING ANY FUEL SYSTEM
COMPONENT.
(2) Release fuel system pressure. Refer to Fuel
Pressure Release Procedure in this group.
(3) Raise and support vehicle.
(4) On YJ models remove the fuel filter shield (Fig.
13).
(5) Remove hoses and clamps from inlet and outlet
sides of filter (Figs. 13 or 14). For procedures, refer to
Fuel Tubes/Lines/Hoses and Clamps. Also refer to
Quick-Connect Fittings. These can be found in the
Fuel Delivery System section of this group.
(6) Remove retaining strap bolt.
(7) Remove filter from vehicle.
INSTALLATION
CAUTION: The ends of the fuel filter are marked for
correct installation. Install filter with the end marked
IN towards fuel tank and the end marked OUT to-
wards engine.
(1) Place fuel filter in retaining strap with the
marked ends in the correct position.
(2) Install retaining strap bolt and tighten to 12
Nzm (106 in. lbs.) torque.
(3) Install inlet and outlet hoses and hose clamps.
For procedures, refer to Fuel Tubes/Lines/Hoses and
Clamps. Also refer to Quick-Connect Fittings. These
can be found in the Fuel Delivery System section of
this group.
(4) On YJ models, install fuel filter shield (Fig. 13).
(5) Lower vehicle.
(6) Connect negative battery cable.
(7) Start engine and check for leaks.
FUEL TUBES/LINES/HOSES AND CLAMPS
Also refer to the proceeding section on Quick-Con-
nect Fittings.
Fig. 13 Fuel Filter and ShieldÐYJ Models
Fig. 14 Fuel FilterÐXJ Models
JFUEL DELIVERY SYSTEM 14 - 9

WARNING: THE FUEL SYSTEM IS UNDER A CON-
STANT PRESSURE (EVEN WITH THE ENGINE OFF).
BEFORE SERVICING ANY FUEL SYSTEM HOSES,
FITTINGS OR LINES, THE FUEL SYSTEM PRES-
SURE MUST BE RELEASED. REFER TO THE FUEL
PRESSURE RELEASE PROCEDURE IN THIS
GROUP.
Inspect all hose connections such as clamps, cou-
plings and fittings to make sure they are secure and
leaks are not present. The component should be re-
placed immediately if there is any evidence of degra-
dation that could result in failure.
Never attempt to repair a plastic fuel line/tube. Re-
place as necessary.
Avoid contact of any fuel tubes/hoses with other ve-
hicle components that could cause abrasions or scuff-
ing. Be sure that the plastic fuel lines/tubes are
properly routed to prevent pinching and to avoid heat
sources.
The lines/tubes/hoses used on fuel injected vehicles
are of a special construction. This is due to the
higher fuel pressures and the possibility of contami-
nated fuel in this system. If it is necessary to replace
these lines/tubes/hoses, only those marked EFM/EFI
may be used.
The hose clamps used to secure rubber hoses on
fuel injected vehicles are of a special rolled edge con-
struction. This construction is used to prevent the
edge of the clamp from cutting into the hose. Only
these rolled edge type clamps may be used in this
system. All other types of clamps may cut into the
hoses and cause high-pressure fuel leaks.
Use new original equipment type hose clamps.
Tighten hose clamps to 1 Nzm (15 in. lbs.) torque.
QUICK-CONNECT FITTINGS
Also refer to the previous Fuel Tubes/Lines/Hoses
and Clamps section.
Different types of quick-connect fittings are used to
attach various fuel system components. These are: a
single-tab type, a two-tab type or a plastic retainer
ring type.
SINGLE-TAB TYPE
This type of fitting is equipped with a single pull
tab (Fig. 15). The tab is removable. After the tab is
removed, the quick-connect fitting can be separated
from the fuel system component.
CAUTION: The interior components (O-rings, spac-
ers) of this type of quick-connect fitting are not ser-
viced separately, but new pull tabs are available. Do
not attempt to repair damaged fittings or fuel lines/
tubes. If repair is necessary, replace the complete
fuel tube assembly.WARNING: THE FUEL SYSTEM IS UNDER A CON-
STANT PRESSURE (EVEN WITH THE ENGINE OFF).
BEFORE SERVICING ANY FUEL SYSTEM HOSES,
FITTINGS OR LINES, THE FUEL SYSTEM PRES-
SURE MUST BE RELEASED. REFER TO THE FUEL
PRESSURE RELEASE PROCEDURE IN THIS
GROUP.
DISCONNECTION/CONNECTION
(1) Disconnect negative battery cable from battery.
(2) Perform the fuel pressure release procedure.
Refer to the Fuel Pressure Release Procedure in this
section.
(3) Clean the fitting of any foreign material before
disassembly.
(4) Press the release tab on the side of fitting to re-
lease pull tab (Fig. 15).
CAUTION: If this release tab is not pressed prior to
releasing the pull tab, the pull tab will be damaged.
(5) While pressing the release tab on the side of
the fitting, use a screwdriver to pry up the pull tab
(Fig. 16).
(6) Raise the pull tab until it separates from the
quick-connect fitting (Fig. 17). Discard the old pull
tab.
(7) Disconnect the quick-connect fitting from the
fuel system component being serviced.
(8) Inspect the quick-connect fitting body and fuel
system component for damage. Replace as necessary.
(9) Prior to connecting the quick-connect fitting to
component being serviced, check condition of fitting
and component. Clean the parts with a lint-free
cloth. Lubricate them with clean engine oil.
(10) Insert the quick-connect fitting into the fuel
tube or fuel system component until the built-on stop
on the fuel tube or component rests against back of
fitting.
Fig. 15 Single-Tab Type Fitting
14 - 10 FUEL DELIVERY SYSTEMJ

(11) Obtain a new pull tab. Push the new tab down
until it locks into place in the quick-connect fitting.
(12) Verify a locked condition by firmly pulling on
fuel tube and fitting (15-30 lbs.).
(13) Connect negative cable to battery.
(14) Start engine and check for leaks.
TWO-TAB TYPE FITTING
This type of fitting is equipped with tabs located on
both sides of the fitting (Fig. 18). These tabs are sup-
plied for disconnecting the quick-connect fitting from
component being serviced.
CAUTION: The interior components (O-rings, spac-
ers) of this type of quick-connect fitting are not ser-
viced separately, but new plastic retainers are
available. Do not attempt to repair damaged fittings
or fuel lines/tubes. If repair is necessary, replace
the complete fuel tube assembly.
WARNING: THE FUEL SYSTEM IS UNDER A CON-
STANT PRESSURE (EVEN WITH THE ENGINE OFF).BEFORE SERVICING ANY FUEL SYSTEM HOSES,
FITTINGS OR LINES, THE FUEL SYSTEM PRES-
SURE MUST BE RELEASED. REFER TO THE FUEL
PRESSURE RELEASE PROCEDURE IN THIS
GROUP.
DISCONNECTION/CONNECTION
(1) Disconnect negative battery cable from the bat-
tery.
(2) Perform the fuel pressure release procedure.
Refer to the Fuel Pressure Release Procedure in this
section.
(3) Clean the fitting of any foreign material before
disassembly.
(4) To disconnect the quick-connect fitting, squeeze
the plastic retainer tabs against the sides of the
quick-connect fitting with your fingers. Tool use is
not required for removal and may damage plastic re-
tainer. Pull the fitting from the fuel system compo-
nent being serviced. The plastic retainer will remain
on the component being serviced after fitting is dis-
connected. The O-rings and spacer will remain in the
quick-connect fitting connector body.
(5) Inspect the quick-connect fitting body and com-
ponent for damage. Replace as necessary.
CAUTION: When the quick-connect fitting was dis-
connected, the plastic retainer will remain on the
component being serviced. If this retainer must be
removed, very carefully release the retainer from
the component with two small screwdrivers. After
removal, inspect the retainer for cracks or any dam-
age.
(6) Prior to connecting the quick-connect fitting to
component being serviced, check condition of fitting
and component. Clean the parts with a lint-free
cloth. Lubricate them with clean engine oil.
Fig. 16 Disconnecting Single-Tab Type Fitting
Fig. 17 Removing Pull Tab
Fig. 18 Typical Two-Tab Type Quick-Connect Fitting
JFUEL DELIVERY SYSTEM 14 - 11

(7) Insert the quick-connect fitting to the compo-
nent being serviced and into the plastic retainer.
When a connection is made, a click will be heard.
(8) Verify a locked condition by firmly pulling on
fuel tube and fitting (15-30 lbs.).
(9) Connect negative cable to battery.
(10) Start engine and check for leaks.
PLASTIC RETAINER RING TYPE FITTING
This type of fitting can be identified by the use of a
full-round plastic retainer ring (Fig. 19) usually black
in color.
CAUTION: The interior components (O-rings, spac-
ers, retainers) of this type of quick-connect fitting
are not serviced separately. Do not attempt to repair
damaged fittings or fuel lines/tubes. If repair is nec-
essary, replace the complete fuel tube assembly.WARNING: THE FUEL SYSTEM IS UNDER A CON-
STANT PRESSURE (EVEN WITH THE ENGINE OFF).
BEFORE SERVICING ANY FUEL SYSTEM HOSES,
FITTINGS OR LINES, THE FUEL SYSTEM PRES-
SURE MUST BE RELEASED. REFER TO THE FUEL
PRESSURE RELEASE PROCEDURE IN THIS
GROUP.
DISCONNECTION/CONNECTION
(1) Disconnect negative battery cable from the bat-
tery.
(2) Perform the fuel pressure release procedure.
Refer to the Fuel Pressure Release Procedure in this
section.
(3) Clean the fitting of any foreign material before
disassembly.
(4) To release the fuel system component from the
quick-connect fitting, firmly push the fitting towards
the component being serviced while firmly pushing
the plastic retainer ring into the fitting (Fig. 19).
With the plastic ring depressed, pull the fitting from
the component.The plastic retainer ring must be
pressed squarely into the fitting body. If this re-
tainer is cocked during removal, it may be dif-
ficult to disconnect fitting. Use an open-end
wrench on the shoulder of the plastic retainer
ring to aid in disconnection.
After disconnection, the plastic retainer ring will
remain with the quick-connect fitting connector body.
(5) Inspect fitting connector body, plastic retainer
ring and fuel system component for damage. Replace
as necessary.
(6) Prior to connecting the quick-connect fitting to
component being serviced, check condition of fitting
and component. Clean the parts with a lint-free
cloth. Lubricate them with clean engine oil.
(7) Insert the quick-connect fitting into the compo-
nent being serviced until a click is felt.
(8) Verify a locked condition by firmly pulling on
fuel tube and fitting (15-30 lbs.).
(9) Connect negative battery cable to battery.
(10) Start engine and check for leaks.
Fig. 19 Plastic Retainer Ring Type Fitting
14 - 12 FUEL DELIVERY SYSTEMJ