1998 DODGE RAM 1500 Evap

OPERATION
Fuel is returned through the fuel pump module
and back into the fuel tank through the fuel filter/
fuel pressure regulator. A separate fuel return line
from the engine to the tank is not used.
The fuel tank assembly consists of: the fuel tank,
fuel pump module assembly, fuel pump module lock-
nut/gasket, and fuel tank check valve (refer to Fuel
Tank Check Valve for information).
A fuel filler/vent tube assembly using a pressure/
vacuum, 1/4 turn fuel filler cap is used. The fuel
filler tube contains a flap door located below the fuel
fill 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 Emission Control
Systems.
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.
STANDARD PROCEDURE - FUEL SYSTEM
PRESSURE RELEASE
Use following procedure if the fuel injector
rail is, or is not equipped with a fuel pressure
test port.
(1) Remove fuel fill cap.
Fig. 1 FUEL DELIVERY COMPONENTS
1 - FUEL TANK 8 - LDP FRESH AIR FILTER
2 - CHECK VALVE 9 - LEAK DETECTION PUMP
3 - LIQUID EXPANSION CHAMBER 10 - EVAP CANISTERS (2)
4 - FUEL FILTER / FUEL PRESSURE REGULATOR 11 - FUEL TANK STRAPS (2)
5 - QUICK-CONNECT FITTING AND FUEL LINE (TO ENGINE) 12 - CHECK VALVE
6 - EVAP LINE CONNECTION 13 - FUEL PUMP MODULE LOCK RING
7 - LEAK DETECTION PUMP FRESH AIR LINE 14 - FUEL PUMP MODULE
14 - 2 FUEL DELIVERY - GASDR
FUEL DELIVERY - GAS (Continued)

DESCRIPTION N-m Ft. Lbs. In. Lbs.
Engine Coolant
Temperature Sensor -
5.7L11 - 9 6
EVAP Canister- to-Bracket
Nuts8.5 - 75
EVAP Canister-to-frame
bolts34 25
Fuel Filler Hose Clamp at
Tank3-30
Fuel Filler Housing-to-
Body Screws2-17
Fuel Pump Module Lock
Ring54 40 -
Fuel Rail Mounting Bolts -
3.7L11 -
100
Fuel Rail Mounting Bolts -
4.7L11 - 100
Fuel Rail Mounting Bolts -
5.7L11 - 100
Fuel Tank Mounting Straps 41 30 -
IAC Motor Mounting
Screws - 3.7L7-60
IAC Motor Mounting
Screws - 4.7L7-60
Leak Detection Pump
Mounting Bolt8.5 - 75
Map Sensor Mounting
Screws - 3.7L3-25
Map Sensor Mounting
Screws - 4.7L3-25
PCM-to-Mounting Bracket
Mounting Screws4-35
Power Steering Pressure
Switch - 3.7L14-22 - 124-195
Power Steering Pressure
Switch - 4.7L14-22 - 124-195
TPS Mounting Screws -
3.7L7-60
TPS Mounting Screws -
4.7L7-60
Throttle Body Mounting
Bolts - 3.7L11 - 100
Throttle Body Mounting
Bolts - 4.7L12 - 105
Throttle Body Mounting
Bolts - 5.7L12 - 105
Oxygen Sensors 30 22 -
14 - 4 FUEL DELIVERY - GASDR
FUEL DELIVERY - GAS (Continued)

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 58   2 psi at the
fuel injectors. It contains a diaphragm, calibrated
springs and a fuel return valve. The internal fuel fil-
ter (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.
If fuel pressure at the pressure regulator exceeds
approximately 60 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 current
source is supplied to the resistor track on the fuel
gauge sending unit. This is fed directly from the
Powertrain Control Module (PCM).NOTE: For
diagnostic purposes, this 12V power source can
only be verified with the circuit opened (fuel
pump module electrical connector unplugged).
With the connectors 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
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.
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
14 - 6 FUEL DELIVERY - GASDR
FUEL FILTER/PRESSURE REGULATOR (Continued)

(15) Install air duct to air box.
(16) Connect battery cable to battery.
(17) Start engine and check for leaks.
5.7L V-8
(1) If fuel injectors are to be installed, refer to Fuel
Injector Removal/Installation.
(2) Clean out fuel injector machined bores in
intake manifold.
(3) Apply a small amount of engine oil to each fuel
injector o-ring. This will help in fuel rail installation.
(4) Position fuel rail/fuel injector assembly to
machined injector openings in intake manifold.
(5) Guide each injector into intake manifold. Be
careful not to tear injector o-rings.
(6) Pushrightside of fuel rail down until fuel
injectors have bottomed on shoulders. Pushleftfuel
rail down until injectors have bottomed on shoulders.
(7) Install 4 fuel rail holdown clamps and 4 mount-
ing bolts. Refer to Torque Specifications.
(8) Position spark plug cable tray and cable assem-
bly to intake manifold. Snap 4 cable tray retaining
clips into intake manifold.
(9) Install all cables to spark plugs and ignition
coils.
(10) Connect electrical connector to throttle body.
(11) Install electrical connectors to all 8 ignition
coils. Refer to Ignition Coil Removal/Installation.
(12) Connect electrical connector to throttle body.
(13) Connect electrical connectors at all fuel injec-
tors. To install connector, refer to (Fig. 17). Push con-
nector onto injector (1) and then push and lock red
colored slider (2). Verify connector is locked to injec-
tor by lightly tugging on connector.
(14) Connect fuel line latch clip and fuel line to
fuel rail. Refer to Quick-Connect Fittings.
(15) Install air resonator to throttle body (2 bolts).
(16) Install flexible air duct to air box.
(17) Connect battery cable to battery.
(18) Start engine and check for leaks.
FUEL TANK
DESCRIPTION
The fuel tank is constructed of a plastic material.
Its main functions are for fuel storage and for place-
ment of the fuel pump module, and (if equipped) cer-
tain ORVR components.
OPERATION
All models pass a full 360 degree rollover test
without fuel leakage. To accomplish this, fuel and
vapor flow controls are required for all fuel tank con-
nections.Two check (control) valves are mounted into the
top of the fuel tank. Refer to Fuel Tank Check Valve
for additional information.
An evaporation control system is connected to the
fuel tank to reduce emissions of fuel vapors into the
atmosphere. When fuel evaporates from the fuel
tank, vapors pass through vent hoses or tubes to a
charcoal canister where they are temporarily held.
When the engine is running, the vapors are drawn
into the intake manifold. Certain models are also
equipped with a self-diagnosing system using a Leak
Detection Pump (LDP) and/or an On-Board Refueling
Vapor Recovery (ORVR) system. Refer to Emission
Control System for additional information.
REMOVAL- EXCEPT DIESEL
Fuel Tank Draining
WARNING: THE FUEL SYSTEM MAY BE UNDER
CONSTANT FUEL PRESSURE EVEN WITH THE
ENGINE OFF. THIS PRESSURE MUST BE
RELEASED BEFORE SERVICING FUEL TANK.
Two different procedures may be used to drain fuel
tank: through the fuel fill fitting on tank, or using
the DRBtscan tool. Due to a one-way check valve
installed into the fuel fill opening fitting at the tank,
the tank cannot be drained conventionally at the fill
cap.
The quickest draining procedure involves removing
the rubber fuel fill hose.
As an alternative procedure, the electric fuel pump
may be activated allowing tank to be drained at fuel
rail connection. Refer to DRB scan tool for fuel pump
activation procedures. Before disconnecting fuel line
at fuel rail, release fuel pressure. Refer to the Fuel
System Pressure Release Procedure for procedures.
Attach end of special test hose tool number 6541,
6539, 6631 or 6923 at fuel rail disconnection (tool
number will depend on model and/or engine applica-
tion). Position opposite end of this hose tool to an
approved gasoline draining station. Activate fuel
pump and drain tank until empty.
If electric fuel pump is not operating, fuel must be
drained through fuel fill fitting at tank. Refer to fol-
lowing procedures.
(1) Release fuel system pressure.
(2) Raise vehicle.
(3) Thoroughly clean area around fuel fill fitting
and rubber fuel fill hose at tank.
(4) If vehicle is equipped with 4 doors and a 6 foot
(short) box, remove left-rear tire/wheel.
(5) Loosen clamp (Fig. 23) and disconnect rubber
fuel fill hose at tank fitting. Using an approved gas
holding tank, drain fuel tank through this fitting.
DRFUEL DELIVERY - GAS 14 - 17
FUEL RAIL (Continued)

Tank Removal
(1) Loosen clamp and disconnect rubber fuel vent
hose (Fig. 23) at tank fitting.
(2) Support tank with a hydraulic jack.
(3) Remove 2 fuel tank strap nuts (Fig. 24) and
remove both tank support straps.
(4) Carefully lower tank a few inches and discon-
nect fuel pump module electrical connector (Fig. 25)
at top of tank. To disconnect electrical connector:
Push upward on red colored tab to unlock. Push on
black colored tab while removing connector.(5) Disconnect fuel line at fuel filter / fuel pressure
regulator (Fig. 25) by pressing on tabs at side of
quick-connect fitting.
(6) Disconnect EVAP line at top of tank (Fig. 1).
(7) Continue to lower tank for removal.
(8) If fuel tank is to be replaced, remove fuel pump
module from tank. Refer to Fuel Pump Module
Removal/Installation procedures.
Fig. 23 FUEL TANK FILL / VENT HOSES
1 - BEZEL SCREWS
2 - FUEL FILL BEZEL
3 - HOSE CLAMPS4 - VENT HOSE
5 - FUEL TANK
6 - FILL HOSE
14 - 18 FUEL DELIVERY - GASDR
FUEL TANK (Continued)

INSTALLATION - EXCEPT DIESEL
(1) If fuel tank is to be replaced, install fuel pump
module into tank. Refer to Fuel Pump Module
Removal/Installation procedures.
(2) Disconnect clamps and remove rubber fuel fill
hose and fuel vent hose at fuel fill tube. Install these
2 hoses to 2 fuel tank fittings. Rotate hoses until
paint marks on hoses line up with alignment marks
(Fig. 26). Tighten both clamps.
(3) Position fuel tank to hydraulic jack.
(4) Raise tank until positioned near body.
(5) Connect EVAP line at tank (Fig. 1).
(6) Connect fuel pump module electrical connector
(Fig. 25) at top of tank.
(7) Connect fuel line quick-connect fitting to fuel
filter / fuel pressure regulator (Fig. 1) or (Fig. 25).
(8) Continue raising tank until positioned snug to
body.(9) Install and position both tank support straps.
Install 2 fuel tank strap nuts (Fig. 24) and tighten.
Tighten rear strap nut first.Refer to Torque Spec-
ifications.
(10) Connect rubber fill and vent hoses to fuel fill
tube and tighten clamps.
(11) Lower vehicle.
(12) Fill fuel tank with fuel.
(13) Start engine and check for fuel leaks near top
of module.
Fig. 24 FUEL TANK MOUNTING
1 - FUEL TANK
2 - STRAP MOUNTING STUDS
3 - VEHICLE FRAME4 - MOUNTING STRAPS
5 - STRAP NUTS
DRFUEL DELIVERY - GAS 14 - 19
FUEL TANK (Continued)

This will ensure proper gear-to-shaft tighten-
ing.
(5) Clean pump gear and pump shaft at machined
tapers with an evaporative type cleaner such as
brake cleaner.
(6) Position injection pump to mounting flange on
gear housing while aligning injection pump shaft
through back of injection pump gear.
(7) After pump is positioned flat to mounting
flange, install 3 pump mounting nuts and tighten
finger tight only.Do not attempt a final tightening
at this time.Do not attempt to tighten (pull)
pump to gear housing using mounting nuts.
Damage to pump or gear cover may occur. The
pump must be positioned flat to its mounting
flange before attempting to tighten 3 mounting
nuts.
(8) To prevent damage or cracking of components,
install and tighten nuts in the following sequence:
(a) Install injection pump shaft washer and nut
to pump shaft. Tighten nutfinger tight only.
(b) Do preliminary (light) tightening of injection
pump shaft nut.
(c) Tighten 3 injection pump mounting nuts to
24 N´m (18 ft. lbs.).(d) Do a final tightening of pump shaft nut to
105 N´m (77 ft. lbs.).
(9) Install drive gear access cover (plate) using a
3/8º drive ratchet. Plate is threaded to timing gear
cover. Tighten to 8 N´m (71 in. lbs.) torque.
(10) Install fuel line (injection pump-to-pressure
limiting valve). Tighten bolts to 24 N´m (18 ft. lbs.)
torque.
(11) Install fuel line (injection pump-to-fuel rail).
(a) Tighten fitting at fuel pump to 37 N´m (27 ft.
lbs.) torque. Use a back-up wrench.
(b) Tighten fitting at fuel rail to 37 N´m (27 ft.
lbs.) torque.
(12) Install fuel line (injection pump-to-fuel filter
housing). Tighten to 24 N´m (18 ft. lbs.) torque.
(13) Connect Fuel Control Actuator (FCA) electri-
cal connector to rear of injection pump.
(14) Install intake manifold air intake tube (above
injection pump). Tighten clamps.
(15) Install accessory drive belt.
(16) Install cooling fan shroud.
(17) Install cooling fan assembly.
(18) Connect both negative battery cables to both
batteries.
(19) Check system for fuel or engine oil leaks.
Fig. 12 FUEL INJECTION PUMP REMOVAL/INSTALLATION
1 - PUMP DRIVE GEAR NUT
2 - WASHER
3 - PUMP DRIVE GEAR
4 - RUBBER O-RING
5 - FUEL INJECTION PUMP6 - PUMP MOUNTING NUTS (3)
7 - PUMP MOUNTING STUDS (3)
8 - O-RING MACHINED GROOVE
9 - FRONT TIMING GEAR HOUSING
14 - 56 FUEL DELIVERY - DIESELDR
FUEL INJECTION PUMP (Continued)

HEATING & AIR CONDITIONING
TABLE OF CONTENTS
page page
HEATING & AIR CONDITIONING
DESCRIPTION
DESCRIPTION - ENGINE COOLING
SYSTEM REQUIREMENTS...............1
DESCRIPTION - HEATER AND AIR
CONDITIONER........................1
OPERATION - HEATER AND AIR
CONDITIONER........................1
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - A/C
PERFORMANCE.......................3DIAGNOSIS AND TESTING - HEATER
PERFORMANCE TEST..................6
SPECIFICATIONS - A/C SYSTEM............7
CONTROLS.............................9
DISTRIBUTION..........................26
PLUMBING.............................41
HEATING & AIR
CONDITIONING
DESCRIPTION
DESCRIPTION - ENGINE COOLING SYSTEM
REQUIREMENTS
To maintain the performance level of the heating,
ventilation and air conditioning (HVAC) system, the
engine cooling system must be properly maintained.
The use of a bug screen is not recommended. Any
obstructions in front of the radiator or A/C condenser
will reduce the performance of the A/C and engine
cooling systems.
The engine cooling system includes the radiator,
thermostat, radiator hoses and the engine coolant
pump. Refer to Cooling for more information before
opening or attempting any service to the engine cool-
ing system.
DESCRIPTION - HEATER AND AIR
CONDITIONER
A manually controlled single zone type heating-air
conditioning system or a manually controlled dual
zone type heating-air conditioning system is available
on this model.
All vehicles are equipped with a common heater,
ventilation and air conditioning (HVAC) housing (Fig.
1). The system combines air conditioning, heating,
and ventilating capabilities in a single unit housing
mounted within the passenger compartment under
the instrument panel. The HVAC housing includes:
²Blower motor
²Blower motor resistor block²Heater core
²Evaporator coil
²Blend door and actuator
²Defrost door and actuator
²Mode door and actuator
²Recirculation door and actuator
Based upon the system and mode selected, condi-
tioned air can exit the HVAC housing through one or
a combination of the three main housing outlets:
defrost, panel or floor. The defrost outlet is located on
the top of the housing, the panel outlet is located on
the face of the housing and the floor outlet is located
on the bottom of the housing. Once the conditioned
air exits the unit housing, it is further directed
through molded plastic ducts to the various outlets in
the vehicle interior. These outlets and their locations
are as follows:
²Defroster Outlet- A single large defroster out-
let is located in the center of the instrument panel
top cover, near the base of the windshield.
²Side Window Demister Outlets- There are
two side window demister outlets, one is located at
each outboard end of the instrument panel top cover,
near the belt line at the A-pillars.
²Panel Outlets- There are four panel outlets in
the instrument panel, one located near each outboard
end of the instrument panel facing the rear of the
vehicle and two located near the top of the instru-
ment panel center bezel.
²Front Floor Outlets- There are two front floor
outlets, one located above each side of the floor panel
center tunnel near the dash panel.
OPERATION - HEATER AND AIR CONDITIONER
The heating and air conditioning systems pulls
outside (ambient) air through the cowl opening at the
base of the windshield, then into the plenum cham-
DRHEATING & AIR CONDITIONING 24 - 1