DODGE NEON 1999 Service Repair Manual

FUEL SYSTEM
CONTENTS
page page
FUEL DELIVERY SYSTEM................... 3
FUEL INJECTION SYSTEM................. 20GENERAL INFORMATION................... 1
GENERAL INFORMATION
INDEX
page page
GENERAL INFORMATION
FUEL REQUIREMENTS.................... 1
GASOLINE/OXYGENATE BLENDS............ 1INTRODUCTION......................... 1
PCM REPLACEMENT..................... 1
GENERAL INFORMATION
INTRODUCTION
Throughout this group, references may be made to
a particular vehicle by letter or number designation.
A chart showing the breakdown of these designations
is included in the Introduction Section at the front of
this service manual.
The Evaporation Control System, is also considered
part of the fuel system. The system reduces the emis-
sion of fuel vapor into the atmosphere.
The description and function of the Evaporation
Control System is found in Group 25 of this manual.
PCM REPLACEMENT
USE THE DRB SCAN TOOL TO REPROGRAM
THE NEW PCM WITH THE VEHICLES ORIGI-
NAL IDENTIFICATION NUMBER (VIN) AND
THE VEHICLES ORIGINAL MILEAGE. IF THIS
STEP IS NOT DONE A DIAGNOSTIC TROUBLE
CODE (DTC) MAY BE SET.
FUEL REQUIREMENTS
Your vehicle was designed to meet all emission reg-
ulations and provide excellent fuel economy when
using high quality unleaded gasoline.
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 reported to yourdealer immediately. Engine damage 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 detergents,
corrosion and stability additives are recommended.
Using gasolines that have these additives will help
improve fuel economy, reduce emissions, and main-
tain vehicle performance.
Poor quality gasoline can cause problems such as
hard starting, stalling, and stumble. If you experi-
ence these problems, try 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
(Methyl Tertiary Butyl Ether) and ETBE (Ethyl Ter-
tiary Butyl Ether). Oxygenates are required in some
areas of the country during winter months to reduce
carbon monoxide emissions. The type and amount of
oxygenate used in the blend is important.
The following are generally used in gasoline
blends:
Ethanol- (Ethyl or Grain Alcohol) properly
blended, is used as a mixture of 10 percent ethanol
and 90 percent gasoline. Gasoline blended with etha-
nol may be used in your vehicle.
MTBE/ETBE- Gasoline and MTBE (Methyl Ter-
tiary Butyl Ether) blends are a mixture of unleaded
gasoline and up to 15 percent MTBE. Gasoline and
ETBE (Ethyl Tertiary Butyl Ether) are blends of gas-
PLFUEL SYSTEM 14 - 1

oline and up to 17 percent ETBE. Gasoline blended
with MTBE or ETBE may be used in your vehicle.
Methanol- Methanol (Methyl or Wood Alcohol) is
used in a variety of concentrations blended with
unleaded gasoline. You may encounter fuels contain-
ing 3 percent or more methanol along with other
alcohols called cosolvents.
DO NOT USE GASOLINES CONTAINING
METHANOL.
Use of methanol/gasoline blends may result in
starting and driveability problems and damage criti-
cal fuel system components.
Problems that are the result of using methanol/
gasoline blends are not the responsibility of Chrysler
Corporation and may not be covered by the vehicle
warranty.
Reformulated Gasoline
Many areas of the country are requiring the use of
cleaner-burning fuel referred to asReformulatedGasoline. Reformulated gasolines are specially
blended to reduce vehicle emissions and improve air
quality.
Chrysler Corporation strongly supports the use of
reformulated gasolines whenever available. Although
your vehicle was designed to provide optimum perfor-
mance and lowest emissions operating on high qual-
ity unleaded gasoline, it will perform equally well
and produce even lower emissions when operating on
reformulated gasoline.
Materials Added to Fuel
Indiscriminate use of fuel system cleaning agents
should be avoided. Many of these materials intended
for gum and varnish removal may contain active sol-
vents of similar ingredients that can be harmful to
fuel system gasket and diaphragm materials.
14 - 2 FUEL SYSTEMPL
GENERAL INFORMATION (Continued)

FUEL DELIVERY SYSTEM
INDEX
page page
DESCRIPTION AND OPERATION
ELECTRIC FUEL PUMP.................... 4
FUEL DELIVERY SYSTEM.................. 3
FUEL FILTER/FUEL PRESSURE REGULATOR . . . 4
FUEL GAUGE SENDING UNIT............... 4
FUEL INJECTORS........................ 5
FUEL PUMP MODULE..................... 3
FUEL RAIL.............................. 4
FUEL TANK............................. 4
PRESSURE-VACUUM FILLER CAP........... 5
QUICK-CONNECT FITTINGS................ 5
ROLLOVER VALVES...................... 5
DIAGNOSIS AND TESTING
FUEL INJECTORS........................ 8
FUEL LEVEL SENSOR..................... 6
FUEL PUMP PRESSURE TEST.............. 6
SERVICE PROCEDURES
DRAINING FUEL TANK.................... 10
FUEL SYSTEM PRESSURE RELEASE
PROCEDURE......................... 10HOSES AND CLAMPS.................... 10
QUICK-CONNECT FITTINGS............... 11
REMOVAL AND INSTALLATION
ACCELERATOR PEDAL................... 17
AUTOMATIC SHUTDOWN RELAY........... 11
FUEL FILLER NECK...................... 16
FUEL FILLER TUBE ROLLOVER VALVE....... 16
FUEL FILTER / PRESSURE REGULATOR..... 12
FUEL INJECTORS....................... 14
FUEL LEVEL SENSOR.................... 13
FUEL PUMP INLET STRAINER............. 13
FUEL PUMP MODULE.................... 11
FUEL PUMP RELAY...................... 11
FUEL TANK............................ 15
THROTTLE CABLEÐAUTOMATIC
TRANSMISSION....................... 18
THROTTLE CABLEÐMANUAL TRANSMISSION . 17
SPECIFICATIONS
FUEL TANK CAPACITY................... 19
TORQUE.............................. 19
DESCRIPTION AND OPERATION
FUEL DELIVERY SYSTEM
The fuel delivery system consists of: the electric
fuel pump, fuel filter/fuel pressure regulator, fuel
tubes/lines/hoses, fuel rail, fuel injectors, fuel tank,
accelerator pedal and throttle cable.
A fuel return system is used on all models (all
engines). 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 no longer used
with any engine.
The fuel tank assembly consists of: the fuel tank,
filler tube, fuel gauge sending unit/electric fuel pump
module, a pressure relief/rollover valve and a pres-
sure-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 PUMP MODULE
The fuel pump module is installed in the top of the
fuel tank (Fig. 1). The fuel pump module contains the
following:²Electric fuel pump
²Fuel pump reservoir
²Inlet strainer
²Fuel filter/pressure regulator
²Fuel gauge sending unit
²Fuel supply line connection
The inlet strainer, fuel pressure regulator and fuel
level sensor are the only serviceable items. If the fuel
pump requires service, replace the fuel pump module.Fig. 1 Fuel Pump Module
PLFUEL SYSTEM 14 - 3

ELECTRIC FUEL PUMP
The electric fuel pump is located in and is part of
the fuel pump module. It is a positive displacement,
gerotor type, immersible pump with a permanent
magnet electric motor. The fuel pump module is sus-
pended in fuel in the fuel tank. The pump draws fuel
through a strainer and pushes it through the motor
to the outlet. The pump contains a check valve. The
valve, in the pump outlet, maintains pump pressure
during engine off conditions. The fuel pump relay
provides voltage to the fuel pump.
The fuel pump has a maximum deadheaded pres-
sure output of approximately 880 kPa (130 psi). The
regulator adjusts fuel system pressure to approxi-
mately 338 kPa (49 psi).
FUEL GAUGE SENDING UNIT
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). The resistor track is used to
send electrical signals to the Powertrain Control
Module (PCM) for fuel gauge operation and for OBD
II emission requirements.
For fuel gauge operation:As fuel level
increases, the float and arm move up. This decreases
the sending unit resistance, causing the fuel gauge to
read full. As fuel level decreases, the float and arm
move down. This increases the sending unit resis-
tance causing the fuel gauge to read empty.
After this fuel level signal is sent to the PCM, the
PCM will transmit the data across the CCD bus cir-
cuits to the instrument panel. Here it is translated
into the appropriate fuel gauge level reading.
FUEL FILTER/FUEL PRESSURE REGULATOR
A combination fuel filter and fuel pressure regula-
tor is used on all gas powered engines. It is located
on the top of the fuel pump module. A separate frame
mounted fuel filter is not used.
Fuel Pressure Regulator Operation:The pres-
sure regulator is a mechanical device that is cali-
brated to maintain fuel system operating pressure of
approximately 338 kPa (49 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.
The fuel pump module contains a check valve to
maintain some fuel pressure when the engine is not
operating. This will help to start the engine.
If fuel pressure at the pressure regulator exceeds
approximately 49 psi, an internal diaphragm closes
and excess fuel pressure is routed back into the tankthrough the pressure regulator. A separate fuel
return line is not used with any gas powered engine.
FUEL TANK
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.
All models are equipped with either one or two
rollover valves mounted into the top of the fuel tank
(or pump module). Refer to Group 25, Emission Con-
trol System for rollover valve information.
An evaporation control system is connected to the
rollover valve(s) 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). Refer to Group 25, Emission
Control System for additional information.
FUEL RAIL
The fuel rail supplies the necessary fuel to each
individual fuel injector and is mounted to the intake
manifold (Fig. 3). The fuel pressure regulator is no
longer mounted to the fuel rail on any engine. It is
now located on the fuel tank mounted fuel pump
module. Refer to Fuel Filter/Fuel Pressure Regulator
in the Fuel Delivery System section of this group for
information. The fuel rail is not repairable.
Fig. 2 Side ViewÐFilter/Regulator
14 - 4 FUEL SYSTEMPL
DESCRIPTION AND OPERATION (Continued)

FUEL INJECTORS
The fuel injectors are 12 ohm electrical solenoids
(Fig. 4). The injector contains a pintle that closes off
an orifice at the nozzle end. When electric current is
supplied to the injector, the armature and needle
move a short distance against a spring, allowing fuel
to flow out the orifice. Because the fuel is under high
pressure, a fine spray is developed in the shape of a
hollow cone. The spraying action atomizes the fuel,
adding it to the air entering the combustion chamber.
The injectors are positioned in the intake manifold.
Fuel injectors are not interchangeable between
engines.
The injectors are positioned in the intake manifold
with the nozzle ends directly above the intake valve
port (Fig. 5).
PRESSURE-VACUUM FILLER CAP
The loss of any fuel or vapor out of the filler neck
is prevented by the use of a safety filler cap. The cap
will release pressure only under significant pressure
of 10.9 to 13.45 kPa (1.58 to 1.95 psi). The vacuum
release for all gas caps is between 0.97 and 2.0 kPa
(0.14 and 0.29 psi). The cap must be replaced by a
similar unit if replacement is necessary.WARNING: REMOVE FILLER CAP TO RELIEVE
TANK PRESSURE BEFORE REMOVING OR REPAIR-
ING FUEL SYSTEM COMPONENTS.
QUICK-CONNECT FITTINGS
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. Some are equipped with safety latch clips.
Refer to the Removal/Installation section for more
information.
CAUTION: The interior components (o-rings, spac-
ers) of quick-connect fitting are not serviced sepa-
rately. Do not attempt to repair damaged fittings or
fuel lines/tubes. If repair is necessary, replace the
complete fuel tube assembly.
Fuel tubes connect fuel system components with
plastic quick-connect fuel fittings. The fitting con-
tains non-serviceable O-ring seals (Fig. 6).
CAUTION: Quick-connect fittings are not serviced
separately. Do not attempt to repair damaged quick-
connect fittings or fuel tubes. Replace the complete
fuel tube/quick-connect fitting assembly.
The quick-connect fitting consists of the O-rings,
retainer and casing (Fig. 6). When the fuel tube
enters the fitting, the retainer locks the shoulder of
the nipple in place and the O-rings seal the tube.
ROLLOVER VALVES
All PL vehicles have two rollover valves. One in
the fuel filler tube and the other on the top of the
fuel tank. The valves prevent fuel flow through the
fuel tank vent valve hoses should the vehicle rollover.
Fig. 3 Fuel RailÐTypical
Fig. 4 Fuel Injector
Fig. 5 Fuel Injector LocationÐTypical
PLFUEL SYSTEM 14 - 5
DESCRIPTION AND OPERATION (Continued)

DIAGNOSIS AND TESTING
FUEL PUMP PRESSURE TEST
The fuel system operates at approximately 338 kPa
(49 psi). Check fuel system pressure at the test port
on the fuel rail (Fig. 7).
(1) Remove cap from fuel pressure test port on fuel
rail.
(2) Connect Fuel Pressure Gauge C-4799B to test
port (Fig. 8).CAUTION: When using the ASD Fuel System Test,
the ASD relay and fuel pump relay remain energized
for 7 minutes or until the test is stopped, or until
the ignition switch is turned to the Off position.
(3) Place the ignition key in the ON position.
Using the DRB scan tool, access ASD Fuel System
Test. The ASD Fuel System Test will activate the fuel
pump and pressurize the system.
²If the gauge reading equals 338 kPa (49 PSI)
further testing is not required. If pressure is not cor-
rect, record the pressure.
²If fuel pressure is below specifications, refer to
the Fuel Pressure Diagnosis Chart (Fig. 9).
²If fuel pressure is above specifications (54 psi or
higher) check for a kinked or restricted fuel supply
line. If the supply line is not kinked or restricted,
replace the Fuel Filter/Pressure Regulator.
(4) Replace Pressure test port cap when finished
doing pressure test.
FUEL LEVEL SENSOR
This procedure tests the resistance of the level sen-
sor itself. It does not test the level sensor circuit.
Refer to Group 8W - Wiring Diagrams for circuit
identification.
The level sensor is a variable resistor. Its resis-
tance changes with the amount of fuel in the tank.
The float arm attached to the sensor moves as the
fuel level changes. To test the level sensor, connect
an ohmmeter across the sensor signal and sensor
ground terminals of the fuel pump module connector
(Fig. 10). Move the float lever to the positions shown
in the resistance chart (Fig. 10). Record the resis-
tance at each point. Replace the level sensor if the
resistance is not within specifications.
Fig. 8 Checking Fuel Pressure at Intake ManifoldÐ
Typical
Fig. 6 Plastic Quick-Connect Fittings
Fig. 7 Fuel Pressure Test PortÐTypical
14 - 6 FUEL SYSTEMPL
DESCRIPTION AND OPERATION (Continued)

Fig. 9 Fuel Pressure Diagnosis Chart
PLFUEL SYSTEM 14 - 7
DIAGNOSIS AND TESTING (Continued)

FUEL INJECTORS
For fuel injector diagnosis, refer to the Fuel Injec-
tor Diagnosis charts. For poor fuel economy diagnosis
or engine miss, also refer to Transmission Driveplate
in this section.
Fig. 10 Level Sensor Diagnosis
14 - 8 FUEL SYSTEMPL
DIAGNOSIS AND TESTING (Continued)

FUEL INJECTOR DIAGNOSIS
PLFUEL SYSTEM 14 - 9
DIAGNOSIS AND TESTING (Continued)