fuel filter DODGE RAM 1999 Service Manual Online

converter lock-up. ECM uses various input signals such as transmission
temperature, output shaft speed, central module timer, engine speed,
APPS and brake switch position to determine operation of transmission
torque converter clutch solenoid. Transmission torque converter clutch
solenoid is located on transmission valve body.
FUEL SYSTEM
FUEL DELIVERY
Fuel Injection Pump
A camshaft-driven Bosch VP44 in-line fuel injection pump is
used to supply high pressure fuel to each fuel injector in precise
metered amounts at the correct time. See Fig. 2. The pump is timed to
camshaft gear. Pump output is controlled by integral Fuel Pump Control
Module (FPCM). Because of electronic control, idle speeds and pump
timing are not adjustable. See ON-VEHICLE ADJUSTMENTS - TRUCKS -
DIESEL article. FPCM can operate engine if crankshaft position sensor
signal does not exist. Fuel injection occurs near completion of
compression stroke for each cylinder.
Fuel injection pump contains an overflow valve which allows
excess fuel to return to the fuel tank. Overflow valve is located on
side of fuel injection pump and is used to attach the fuel return line
to the fuel injection pump.
Fuel Transfer Pump
Fuel transfer pump is located on driver's side of cylinder
block, above starter. See Fig. 2. A 12 volt, 12-amp electric vane-type
pump supplies low fuel pressure from fuel tank, through fuel
heater/fuel filter/water separator to fuel injection pump. Fuel
transfer pump contains internal check valves to prevent fuel from
bleeding back into fuel tank during engine shutdown. Pump will self
prime with ignition on for 2 seconds. Pump has 2 modes, 100 percent
duty cycle (10 psi) when engine is running and 25 percent duty cycle
(7 psi) when engine is cranking.
Fuel Filter/Water Separator
Fuel filter/water separator, located on left side of engine,
protects injection pump by removing water and contaminants from fuel.
See Fig. 2 . Assembly also includes fuel heater and Water-In-Fuel (WIF)
sensor.
In-Tank Fuel Filter
A separate in-tank fuel filter is attached to bottom of fuel
tank module. In-tank fuel filter does not require service under normal
conditions.
FUEL CONTROL
Fuel Injector
Fuel injector delivers atomized fuel into the cylinder.
During fuel injection, fuel pressure from fuel injection pump
increases to fuel injector opening pressure or pop pressure of 4500
psi (316 kg/cm

). This is the pressure required to lift fuel injector
needle valve from its seat, allowing fuel to be injected into the
cylinder. Once fuel pressure decreases to less then the opening
pressure, a spring forces needle valve closed and stops fuel injection
into the cylinders. Each fuel injector is connected to injection pump
by a high pressure (as much as 17,405 psi) line.
Fuel Injection Timing
Pump output is controlled by integral Fuel Pump Control

Module (FPCM). Because of electronic control, pump timing is not
adjustable. See ON-VEHICLE ADJUSTMENTS - TRUCKS - DIESEL article.
FUEL FILTER/WATER SEPARATOR
Fuel filter/water separator is located on left side of engine
and contains fuel heater, Water-In-Fuel (WIF) sensor and drain valve.
See Fig. 2 . The WIF sensor delivers an input signal to Engine Control
Module (ECM) when water exists in fuel filter/water separator. ECM
will then turn on WATER-IN-FUEL warning light. WATER-IN-FUEL warning
light is located on instrument panel, just below tachometer. The
WATER-IN-FUEL warning light informs the operator to drain water from
fuel filter/water separator to prevent damage to fuel system
components. Water may be drained from fuel filter/water separator by
using drain valve on fuel filter/water separator.
FUEL HEATER
Fuel heater is used to prevent diesel fuel from waxing during
cold temperatures. Fuel heater is located in fuel filter/water
separator. See Fig. 2. Fuel flows from fuel tank to fuel transfer pump
and then to fuel filter/water separator. Fuel heater contains a fuel
heater temperature sensor that senses the fuel temperature. When
temperature is less than 37-53
F (3-12C), fuel heater temperature
sensor allows current to flow to the fuel heater to warm the fuel.
When temperature is more than 67-83
F (19-28C), fuel heater
temperature sensor turns off the current flow to the fuel heater.
Voltage to operate fuel heater is provided from ignition switch,
through fuel heater relay and to fuel heater. Fuel heater and fuel
heater relay are not controlled by Engine Control Module (ECM).
EMISSION SYSTEMS
INTAKE MANIFOLD AIR HEATER SYSTEM
Intake manifold air heater is used to warm intake air during
cold starting conditions. Heater system consists of 2 relays and 2
grid heaters installed on top of intake manifold. See Fig. 5.
Engine Control Module (ECM) energizes intake manifold air
heater relays to provide voltage to intake manifold air heater before
and after starting depending on input signals from intake manifold air
temperature sensor, engine speed sensor and vehicle speed. Intake
manifold air heater relays are not energized when intake manifold air
temperature is greater than 59
F (15C) or during engine cranking.
Intake manifold air heater relays are mounted on left inner wheelwell,
below left side battery. See Fig. 6.
Intake manifold air temperature sensor monitors intake
manifold air temperature and delivers an input signal to ECM for
controlling intake manifold air heater. Intake manifold air
temperature sensor is located in intake manifold. See Figs. 2 and 4.
SELF-DIAGNOSTIC SYSTEM
DATA LINK CONNECTOR
The Data Link Connector (DLC) is a 16-pin connector located
at lower edge of driver's side of instrument panel, just above the
accelerator pedal. The Engine Control Module (ECM) contains a self-
diagnostic system which stores a Diagnostic Trouble Code (FTC) if an
incorrect signal or no signal is received from certain sensors or
components. FTC may be retrieved from ECM for system diagnosis by

Transmission Governor Pressure Solenoid
See TRANSMISSION GOVERNOR SOLENOID under MISCELLANEOUS
CONTROLS.
Transmission Overdrive/Override (OD/OR) Switch Indicator
Light
See TRANSMISSION OVERDRIVE/OVERRIDE (OD/OR) SWITCH INDICATOR
under MISCELLANEOUS CONTROLS.
Transmission Overdrive (OD) Solenoid
See TRANSMISSION OVERDRIVE (OD) SOLENOID under MISCELLANEOUS
CONTROLS.
FUEL SYSTEM
FUEL DELIVERY
Auto Shutdown (ASD) Relay
See AUTO SHUTDOWN (ASD) RELAY & FUEL PUMP RELAY under
MISCELLANEOUS CONTROLS.
Fuel Pressure Regulator
Fuel pressure regulator is a mechanical device, used to
maintain a constant pressure across fuel injector tip. Spring and
rubber diaphragm will move from an open to closed position keeping
fuel pressure constant. Excess fuel is returned to fuel tank.
Regulator is located in in-tank fuel pump module. Regulator
includes an internal fuel filter. Excess fuel is routed directly into
fuel tank without using a return line. See Fig. 2.
Fig. 2: Cross-Sectional View Of In-Tank Fuel Filter/Fuel Pressure
Regulator (Typical)
Courtesy of Chrysler Corp.
In-Tank Fuel Pump

Fuel pump is a positive displacement, immersible pump with a
permanent magnet electric motor. Fuel is drawn in through a separate
filter/strainer at bottom of fuel pump and pushed through filter to
fuel outlet line (to fuel injectors). Voltage to operate pump is
supplied from fuel pump relay. On some models, fuel pump relay is
activated by ASD relay.
Fuel pump module includes a combination fuel filter/fuel
pressure regulator, fuel pump reservoir, a separate in-tank fuel
filter, pressure relief/rollover valve, fuel gauge sending unit and
fuel supply line. See Fig. 3.
Fig. 3: Identifying Fuel Pump Module Components (Typical)
Courtesy of Chrysler Corp.
FUEL CONTROL
Fuel Injectors
Fuel injectors are electric solenoid valves controlled by
PCM. PCM determines when and length of time (pulse width) injectors
should operate by switching ground path on and off. During start-up,
battery voltage is supplied to injectors through ASD relay. On some
models, battery voltage is supplied by charging system once engine is

Crankcase Ventilation (PCV) system, but does not use a vacuum
controlled valve. See POSITIVE CRANKCASE VENTILATION (PCV).
EVAPORATIVE (EVAP) EMISSIONS SYSTEM
This system stores fuel vapors from fuel tank, preventing
vapors from reaching the atmosphere. As fuel evaporates inside fuel
tank, vapors are routed through vent hoses to charcoal canister where
they are stored until engine is started.
Evaporative Canister Purge Control Solenoid (EVAP-CPCS)
Charcoal canister purging is controlled by PCM through an
EVAP-CPCS. During engine warm-up and for a short period after hot
restarts, PCM energizes EVAP-CPCS, interrupting engine vacuum signal
to charcoal canister.
After engine reaches a predetermined operating temperature
and PCM internal timer has expired, PCM will de-energize EVAP-CPCS,
allowing engine vacuum to purge charcoal canister. EVAP-CPCS will also
be de-energized during certain idle conditions so PCM can update fuel
delivery calibration.
POSITIVE CRANKCASE VENTILATION (PCV)
PCV system uses a vacuum operated valve. A closed engine
crankcase breather/filter, with a hose connecting it to air filter
housing, provides source of air for system. Crankcase blow-by gases
are removed from crankcase through PCV valve with manifold vacuum.
These gases are introduced into incoming air/fuel mixture and become
part of the calibrated mixture.
A non-vacuum operated Crankcase Ventilation (CCV) system is
used on some engines, see CRANKCASE VENTILATION (CCV) SYSTEM.
SELF-DIAGNOSTIC SYSTEM
The PCM monitors several different circuits of engine control
system. If a problem is sensed with a monitored circuit, PCM will
store a Diagnostic Trouble Code (FTC) to aid technician in diagnosis
of system. The Malfunction Indicator Light (MIL), or a scan tool can
be used to read DTCs. For additional information, see SELF-DIAGNOSTICS
- JEEP, TRUCKS & RWD VANS article.
MALFUNCTION INDICATOR LIGHT
Malfunction Indicator Light (MIL) comes on and remains on for\
3 seconds as a bulb test each time ignition switch is turned to ON
position. If PCM receives an incorrect signal or receives no signal
from battery voltage input, charging system, ECT sensor, MAP sensor or
TP sensor, MIL will come on. MIL will also come on if certain
emission-related faults exist. This warns driver that PCM is in limp-
in mode and immediate repairs are necessary. See LIMP-IN MODE under
MISCELLANEOUS CONTROLS. MIL can also be used to display Diagnostic
Trouble Codes (DTCs). For additional information, see SELF-DIAGNOSTICS\
- JEEP, TRUCKS & RWD VANS article.
SERIAL COMMUNICATIONS INTERFACE (SCI)
SCI circuit is used by PCM to send data to and receive data
and sensor activation signals from scan tool. Scan tool uses signals
sent on SCI to display fault messages or Diagnostic Trouble Codes
(DTCs), sensor voltages and device states (On/Off). Scan tool uses S\
CI
to send solenoid and switch activation commands to PCM so that devices
and circuits can be tested. SCI is also used to write SRI mileage to