Dodge Dakota (R1). Manual — part 558
SPECIAL TOOLS
FUEL SYSTEM
Spanner Wrench—6856
Adapters, Fuel Pressure Test—6539 and/or 6631
Fitting, Air Metering—6714
O2S (Oxygen Sensor) Remover/Installer—C-4907
Test Kit, Fuel
Test Kit, Fuel Pressure—C-4799-B
Fuel Line Removal Tool—6782
14 - 4
FUEL DELIVERY
AN
FUEL DELIVERY (Continued)
FUEL FILTER/PRESSURE
REGULATOR
DESCRIPTION
A combination fuel filter and fuel pressure regula-
tor (Fig. 2) is used on all engines. It is located on the
top of the fuel pump module. A separate frame
mounted fuel filter is not used with any engine.
Both fuel filters (at bottom of fuel pump module
and within fuel pressure regulator) are designed for
extended service. They do not require normal sched-
uled maintenance. Filters should only be replaced if
a diagnostic procedure indicates to do so.
OPERATION
Fuel Pressure Regulator Operation: The pres-
sure regulator is a mechanical device that is not con-
trolled by engine vacuum or the powertrain control
module (PCM).
The regulator is calibrated to maintain fuel system
operating pressure of approximately 339 kPa ± 34
kPa (49.2 psi ± 5 psi) at the fuel injectors. It contains
a diaphragm, calibrated springs and a fuel return
valve. The internal fuel filter (Fig. 2) is also part of
the assembly.
Fuel is supplied to the filter/regulator by the elec-
tric fuel pump through an opening tube at the bot-
tom of filter/regulator (Fig. 2).
The regulator acts as a check valve to maintain
some fuel pressure when the engine is not operating.
This will help to start the engine. A second check
valve is located at the outlet end of the electric fuel
pump. Refer to Fuel Pump—Description and
Operation for more information. Also refer to
the Fuel Pressure Leak Down Test and the Fuel
Pump Pressure Tests.
If fuel pressure at the pressure regulator exceeds
approximately 49.2 psi, an internal diaphragm opens
and excess fuel pressure is routed back into the tank
through the bottom of pressure regulator.
Both fuel filters (at bottom of fuel pump module
and within fuel pressure regulator) are designed for
extended service. They do not require normal sched-
uled maintenance. Filters should only be replaced if
a diagnostic procedure indicates to do so.
FUEL LEVEL SENDING UNIT /
SENSOR
DESCRIPTION
The fuel gauge sending unit (fuel level sensor) is
attached to the side of the fuel pump module. The
sending unit consists of a float, an arm, and a vari-
able resistor track (card).
OPERATION
The fuel pump module has 4 different circuits
(wires). Two of these circuits are used for the fuel
gauge sending unit for fuel gauge operation, and for
certain OBD II emission requirements. The other 2
wires are used for electric fuel pump operation.
For Fuel Gauge Operation: A constant input
voltage source of about 12 volts (battery voltage) is
supplied to the resistor track on the fuel gauge send-
ing unit. This is fed directly from the Powertrain
Control Module (PCM). NOTE: For diagnostic pur-
poses, this 12V power source can only be veri-
fied with the circuit opened (fuel pump module
electrical connector unplugged). With the con-
nectors plugged, output voltages will vary from
about 0.6 volts at FULL, to about 8.6 volts at
EMPTY (about 8.6 volts at EMPTY for Jeep
models, and about 7.0 volts at EMPTY for
Dodge Truck models). The resistor track is used to
vary the voltage (resistance) depending on fuel tank
float level. As fuel level increases, the float and arm
move up, which decreases voltage. As fuel level
decreases, the float and arm move down, which
increases
voltage.
The
varied
voltage
signal
is
returned back to the PCM through the sensor return
circuit.
Both of the electrical circuits between the fuel
gauge sending unit and the PCM are hard-wired (not
multi-plexed). After the voltage signal is sent from
the resistor track, and back to the PCM, the PCM
will interpret the resistance (voltage) data and send
Fig. 2 Side View—Filter/Regulator
1 - INTERNAL FUEL FILTER
2 - FUEL FLOW TO FUEL INJECTORS
3 - FUEL FILTER/FUEL PRESSURE REGULATOR
4 - EXCESS FUEL BACK TO TANK
5 - FUEL INLET
6 - RUBBER GROMMET
7 - TOP OF PUMP MODULE
AN
FUEL DELIVERY
14 - 5
a message across the multi-plex bus circuits to the
instrument panel cluster. Here it is translated into
the appropriate fuel gauge level reading. Refer to
Instrument Panel for additional information.
For OBD II Emission Monitor Requirements:
The PCM will monitor the voltage output sent from
the resistor track on the sending unit to indicate fuel
level. The purpose of this feature is to prevent the
OBD II system from recording/setting false misfire
and fuel system monitor diagnostic trouble codes.
The feature is activated if the fuel level in the tank
is less than approximately 15 percent of its rated
capacity. If equipped with a Leak Detection Pump
(EVAP system monitor), this feature will also be acti-
vated if the fuel level in the tank is more than
approximately 85 percent of its rated capacity.
DIAGNOSIS AND TESTING - FUEL GAUGE
SENDING UNIT
The fuel gauge sending unit contains a variable
resistor (track). As the float moves up or down, elec-
trical resistance will change. Refer to 8, Instrument
Panel and Gauges for Fuel Gauge testing. To test the
gauge sending unit only, it must be removed from
vehicle. The unit is part of the fuel pump module.
Refer to Fuel Pump Module Removal/Installation for
procedures. Measure the resistance across the send-
ing unit terminals. With float in up position, resis-
tance should be 20 ohms ±6 ohms. With float in down
position, resistance should be 220 ohms ±6 ohms.
REMOVAL
The fuel gauge sending unit (fuel level sensor) and
float assembly is located on the side of fuel pump
module (Fig. 3) or (Fig. 4). The fuel pump module is
located inside of fuel tank.
(1) Remove fuel tank. Refer to Fuel Tank Removal/
Installation.
(2) Remove fuel pump module. Refer to Fuel Pump
Module Removal/Installation.
(3) 2 Door Models:
(a) Unplug 4–way electrical connector (Fig. 3).
(b) Disconnect 2 sending unit wires at 4–way
connector. The locking collar of connector must be
removed before wires can be released from connec-
tor. Note location of wires within 4–way connector.
(c) The sending unit is retained to pump module
with a small lock tab and notch (Fig. 5). Carefully
push lock tab to the side and away from notch
while sliding sending unit downward on tracks for
removal. Note wire routing while removing unit
from module.
(4) 4 Door Models:
(a) Remove electrical connector at sending unit
terminals.
(b) Press on release tab (Fig. 6) to remove send-
ing unit from pump module.
Fig. 3 Fuel Gauge Sending Unit - 2 Door Models
1 - FUEL FILTER/PRESSURE REGULATOR
2 - ELECTRICAL CONNECTOR
3 - ELECTRIC FUEL PUMP
4 - FUEL GAUGE FLOAT
5 - FUEL PUMP INLET FILTER
6 - FUEL GAUGE SENDING UNIT
7 - MODULE LOCK TABS (3)
Fig. 4 Fuel Gauge Sending Unit Location – 4 Door
Models
1 - FUEL GAUGE FLOAT
2 - PICK-UP FILTER
3 - FUEL GAUGE SENDING UNIT
4 - FUEL FILTER/FUEL PRESSURE REGULATOR
5 - ELECTRIC FUEL PUMP
6 - PIGTAIL WIRING HARNESS
14 - 6
FUEL DELIVERY
AN
FUEL LEVEL SENDING UNIT / SENSOR (Continued)
INSTALLATION
The fuel gauge sending unit (fuel level sensor) and
float assembly is located on the side of fuel pump
module (Fig. 3) or (Fig. 4). The fuel pump module is
located inside of fuel tank.
(1) 2 Door Models:
(a) Position sending unit into tracks. Note wire
routing.
(b) Push unit on tracks until lock tab snaps into
notch.
(c) Connect 2 sending unit wires into 4–way con-
nector and install locking collar.
(d) Connect 4–way electrical connector to mod-
ule.
(2) 4 Door Models:
(a) Position sending unit to pump module and
snap into place.
(b) Connect electrical connector to terminals.
(3) Install fuel pump module. Refer to Fuel Pump
Module Removal/Installation.
(4) Install fuel tank. Refer to Fuel Tank Removal/
Installation.
FUEL LINES
DESCRIPTION
Also refer to Quick-Connect Fittings.
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
SYSTEM PRESSURE RELEASE PROCEDURE IN
THIS GROUP.
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.
If equipped: The hose clamps used to secure rub-
ber hoses on fuel injected vehicles are of a special
rolled edge construction. 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.
FUEL PUMP
DESCRIPTION
The fuel pump is located inside of the fuel pump
module. A 12 volt, permanent magnet, electric motor
powers the fuel pump.
Fig. 5 Fuel Gauge Sending Unit Lock Tab/Tracks - 2
Door Models
1 - FUEL GAUGE SENDING UNIT
2 - LOCK TAB
3 - NOTCH
4 - TRACKS
Fig. 6 Fuel Gauge Sending Unit Release Tab - 4
Door Models
1 - ELECTRICAL CONNECTOR
2 - FUEL GAUGE SENDING UNIT
3 - RELEASE TAB
4 - FUEL PUMP MODULE
AN
FUEL DELIVERY
14 - 7
FUEL LEVEL SENDING UNIT / SENSOR (Continued)
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