1999 DODGE RAM Fuel pressure

tachometer.
2) If WATER-IN-FUEL (WIF) warning light stays on, water
should be drained from fuel filter/water separator. To drain water
from fuel filter/water separator, ensure engine is not running. Place
drain pan below drain tube at fuel filter/water separator. See Fig. 1.
3) Rotate handle on drain valve forward, toward front of
vehicle to OPEN position. Drain valve is located near top of fuel
filter/water separator. See Fig. 1.
4) Allow water to drain until clean flow of diesel fuel
exists. Rotate handle on drain valve back to CLOSE position.
FUEL TRANSFER PUMP
NOTE: A defective fuel transfer pump may cause low power, hard
starting and White smoke. Check fuel transfer pump output
pressure (cranking and starting), pressure drop and fuel
supply.
Fuel Transfer Pump Preliminary Inspection
1) Check for restricted or leaking fuel supply line to fuel
transfer pump or fuel return line located on driver's side of engine.
See Fig. 1 . Repair fuel supply line or fuel return line if restricted
or leaking.
2) Check for fuel leaking from fuel transfer pump. Replace
fuel transfer pump if fuel is leaking. Check fuel transfer pump output
pressure.
Fuel Transfer Pump Output Pressure
1) Clean area around filter fitting plugs, then remove plugs.
See Fig. 7 . Install Test Fittings (AVU1-2). Install Fuel Pressure Test
Gauge (6828) at inlet port. See Fig. 7. To prevent engine starting,
remove fuel injection pump relay, located in power distribution
center.
2) Turn ignition switch to START position. Inlet pressure
should be 5-7 psi. Install fuel injection pump relay. Start engine.
Inlet pressure should be 10 psi. Using a scan tool, clear FTC. FTC may
set when relay is removed. Check pressure drop.
Fig. 7: Checking Fuel Transfer Pump Output Pressure
Courtesy of Chrysler Corp.
Pressure Drop Test
Turn engine off. Move pressure gauge from inlet port to

outlet port. See Fig. 7. Start engine. Outlet pressure should not be
more 5 psi (0.4 kg/cm) less than inlet pressure. If pressure drop is
more than 5 psi (0.4 kg/cm), replace fuel filter and retest pressure.
If pressure drop is less than 5 psi (0.4 kg/cm), check for fuel
supply restriction.
NOTE: Due to very small vacuum specifications, use a scan tool and
Periphal Expansion Port (PEP) module with 0-15 psi transducer\
to perform following test.
Fuel Supply Restriction Test
Ensure transfer pump pressure is okay. Disconnect fuel supply
line at fuel transfer pump inlet. Remove plastic clip from pump inlet
and install in end of fuel supply line. Install 3/8" Adapter Hose
(6631) between fuel supply line and pump inlet. Install transducer
from PEP module to "T" fitting on adapter. Connect scan tool to
module. Start engine. Check vacuum reading with engine at full
throttle with no load. If vacuum reading is less than 6 in. Hg, check
for fuel supply air leaks. If vacuum reading is 6 in. Hg or more,
check fuel line for damage, dents and kinks. Repair as necessary. If
no problem is found, remove fuel module from fuel tank and check for
obstructions. Repair as necessary.
NOTE: A 3' section of 1/4" I.D. clear tubing and a 1/8" NPT fitting
are required for the following test.
Fuel Supply Air Leak Test
Clean area around filter inlet fitting plug, then remove
plug. See Fig. 7. Install 1/8" NPT fitting with 1/4" nipple fitting in
test port. Attach clear hose with a clamp to fitting. Place other end
of hose in a fuel container. Turn ignition switch to START position,
then release to RUN position without starting engine. Fuel transfer
pump should run for 25 seconds. After hose has been purged, watch for
any air bubbles in hose. If no bubbles exist, system is okay. If
bubbles exist, check fuel line, fittings and fuel module in tank.
Repair as necessary.
OVERFLOW VALVE
1) Fuel transfer pump delivers more fuel to fuel injection
pump than needed. Surplus fuel is routed back to fuel tank by overflow
valve. Overflow valve is used to secure fuel return line to side of
fuel injection pump. See Fig. 1. A sticking check valve in the
overflow valve may result in low power. Pressure release is set at 14
psi. (1.0 kg/cm
). If outlet valve is stuck closed, a FTC may set.
2) Clean area around outlet valve and fuel return line.
Remove valve from pump and fitting. Using regulated air pressure, test
valve by blowing into valve inlet. Valve should open at 14-16 psi. (1.
0-1.1 kg/cm
). If valve does not open, replace valve. Reduce air
pressure to 10 psi. (0.7 kg/cm). Valve should close. If valve does
not close, replace valve. Using NEW gaskets, install valve through
banjo fitting into fuel injection pump. Tighten valve to 24 ft. lbs.
(30 N.m).
FUEL INJECTOR & HIGH-PRESSURE FUEL LINES
WARNING: DO NOT allow diesel fuel to contact hot engine when checking
fuel injector, as high exhaust temperatures could cause fire.
Use care when working around high-pressure fuel lines, as
fuel is under extreme pressure and could penetrate skin,
causing personal injury. Wear safety goggles and protective
clothing when checking fuel injectors.

NOTE: A leaking fuel injector or high-pressure fuel line may cause
a rough idle, Black smoke, poor engine performance, poor fuel
economy and fuel knock. Since a leaking high-pressure fuel
line may cause the same symptoms, check for leaking high
-pressure fuel line before checking fuel injector.
1) To determine which injector or line is malfuntioning,
start engine and check each cylinder output using scan tool. If scan
tool is not available, start engine and engine allow to idle. Loosen
high-pressure fuel line nut at each fuel injector in turn and listen
for a decrease in engine speed. Tighten high-pressure fuel line nut to
30 ft. lbs. (40 N.m). Go to next step.
2) To check for a leaking high-pressure fuel line, start
engine and allow engine to idle. Inspect high-pressure fuel lines and
connections for signs of fuel leakage by placing cardboard over high-
pressure fuel line and connection. Note if leak is being detected by
fuel being sprayed onto the cardboard. If leak exists, repair leak by
tightening high-pressure fuel line nut to 30 ft. lbs. (40 N.m) or
replacing high-pressure fuel line as necessary. If high-pressure fuel
line is replaced, bleed air from fuel system. See FUEL LINE BLEEDING
under FUEL SYSTEM in REMOVAL, OVERHAUL & INSTALLATION - TRUCKS -
DIESEL article. If no leaks are found, go to next step.
3) Remove suspect injector. See FUEL INJECTOR under FUEL
SYSTEM in REMOVAL, OVERHAUL & INSTALLATION - TRUCKS - DIESEL article.
Test injector with a diesel fuel injector tester. Follow tester
instructions. Replace fuel injector if fuel injector opening (pop)
pressure is not 4250-4750 psi (299-334 kg/cm
). Replace injector if
any leaks are noted at 291 psi (20 kg/cm) less than opening (pop)
pressure. Inspect injector for burrs, cracks, wear and plugging. Check
spray pattern. If any problems are noted, replace injector.
FUEL INJECTION PUMP TIMING
Improper fuel injection pump timing may result in low power,
excessive smoke and poor fuel economy. To check fuel injection pump
timing, see FUEL INJECTION PUMP TIMING in ADJUSTMENTS - TRUCKS -
DIESEL article.
INTAKE MANIFOLD AIR HEATER
NOTE: Intake manifold air heater is used to heat incoming air
before entering each cylinder. Warming of incoming air aids
in engine starting and improved driveability during cold
ambient temperatures. Engine Control Module (ECM) uses input
signals from various sensors for controlling intake manifold
air heater relays.
SUMMARY
If no faults were found while performing basic diagnostic
procedures, proceed to SELF-DIAGNOSTICS - JEEP, TRUCKS & RWD VANS
article. If no diagnostic trouble codes are found in self-diagnostics,
proceed to TROUBLE SHOOTING - NO CODES - DIESEL article for diagnosis
by symptom (i.e., ROUGH IDLE, NO START, etc.) or intermittent
diagnostic procedures.

Minimum Compression Pressure
Dakota
2.5L ........................................................ (1)
3.9L, 5.2L & 5.9L ............................. 100 psi (690 kPa)\
Durango ........................................ 100 psi (690 kPa)\
Ram Pickup ..................................... 100 psi (690 kPa)\
Ram Van Ram Wagon .............................. 100 psi (690 kPa)\
Maximum Variation Between Cylinders ............................ ( 1)
( 1) - Information is not available from manufacturer.









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FUEL SYSTEM
FUEL PRESSURE RELEASE
WARNING: Fuel system is under high pressure. ALWAYS release fuel
pressure before attempting to open system for testing or
component replacement. DO NOT allow fuel to flow onto engine
or electrical parts while testing fuel system components.
Vehicles With Fuel Rail Test Port
1) Loosen fuel tank filler cap. Ensure ignition is off.
Remove protective cap from fuel rail test port.
2) Place one end of Fuel Pressure Release Hose (C-4799-1)
into an approved fuel container. Attach remaining end of hose to fuel
rail test port. Use care, as fuel system may be under pressure. Fuel
pressure will be released from fuel system. Remove hose, reinstall
protective cap, and fuel tank filler cap.
3) Wait 5 seconds. Use care when disconnecting fuel lines, as
some fuel pressure may still exist in fuel lines.
NOTE: One or more DTCs may set when fuel pump relay is removed.
Clear DTCs from PCM after fuel pressure release procedure. To
clear DTCs from PCM, see CLEARING DTCS under SELF-DIAGNOSTIC
SYSTEM in SELF-DIAGNOSTICS - JEEP, TRUCKS & RWD VANS
article.
Vehicles Without Fuel Rail Test Port
1) Remove gas cap. Using a non-metallic tool, open flapper
valve in filler neck to relieve pressure. Remove fuel pump relay from
Power Distribution Center (PDC). Relays are identified on label under
PDC cover. Start and run engine until it stalls. Attempt to start
engine. Continue restarting engine until it will no longer run. Turn
ignition off.
CAUTION: DO NOT supply power to fuel injector for more than 4 seconds,
or fuel injector may be damaged.
2) Disconnect any fuel injector connector. Connect a jumper
wire between either fuel injector terminal and positive battery
terminal. Connect another jumper wire to other fuel injector terminal.
Momentarily touch other end of jumper wire to negative battery
terminal.
3) Place a shop towel under fuel line quick-connector at fuel
rail. Use care when disconnecting fuel lines, as some fuel pressure
may still exist in fuel lines. Disconnect fuel line quick-connector.
Reinstall fuel pump relay in PDC. Clear DTCs from PCM. To clear DTCs
from PCM, see CLEARING DTCS under SELF-DIAGNOSTIC SYSTEM in SELF-
DIAGNOSTICS - JEEP, TRUCKS & RWD VANS article.
FUEL PRESSURE TEST

NOTE: For additional information on fuel pressure and fuel pump
testing procedures, see appropriate NO TROUBLE CODE (NTC)
TEST and NO START (NS) TEST in SELF-DIAGNOSTICS - JEEP,
TRUCKS & RWD VANS article.
Vehicles With Fuel Rail Test Port
1) Disconnect negative battery cable. Release fuel pressure.
See FUEL PRESSURE RELEASE. Install fuel pressure gauge with hose on
fuel pressure test port.
2) Start engine and allow to idle. Fuel pressure should be
44-54 psi (3.1-3.8 kg/cm
). If no fuel pressure exists and engine will
not start, fuel pump relay and control circuit may be defective. See
FUEL PUMP RELAY.
3) If fuel pressure exceeds specification, fuel pump is okay,
but fuel pressure regulator is defective. Replace fuel pressure
regulator. Fuel pressure regulator is incorporated with the fuel
filter. Fuel filter/fuel pressure regulator is located on top of fuel
tank, in fuel pump module. See REMOVAL, OVERHAUL & INSTALLATION -
TRUCKS & RWD VANS - GASOLINE article.
Vehicles Without Fuel Rail Test Port
1) Disconnect negative battery cable. Release fuel pressure.
See FUEL PRESSURE RELEASE. Fuel pressure gauge is installed between
fuel supply line and fuel line fitting on fuel rail.
2) To disconnect fuel supply line from fuel rail, ensure area
around fuel supply line and fuel rail are clean. Note direction of
latch clip installation. Latch clip is located on top of fuel supply
line at fuel rail. See Fig. 1. Using 2 screwdrivers, pry latch clip
upward, and remove from fuel rail.
3) Pull fuel supply line from fuel rail. Install Adapter
(6923) into fuel rail. Ensure adapter is fully seated in fuel rail.
Install latch clip into fuel rail, with latch clip fingers pointing
downward. If latch clip will not fully seat so latch clip fingers
extend downward below fitting on fuel rail, adapter may not be fully
seated in fuel rail.
4) Connect fuel supply line to adapter. Ensure fuel supply
line fully seats in adapter. Remove protective cap from test port, and
install Fuel Pressure Gauge/Hose (5069) at test port.
5) Start engine and allow to idle. Fuel pressure should be
44-54 psi (3.1-3.8 kg/cm
). If no fuel pressure exists and engine will
not start, fuel pump relay and control circuit may be defective. See
FUEL PUMP RELAY.
6) If fuel pressure exceeds specification, fuel pump is okay,
but fuel pressure regulator is defective. Replace fuel pressure
regulator. Fuel pressure regulator is incorporated with the fuel
filter. Fuel filter/fuel pressure regulator is located on top of fuel
tank, in fuel pump module. See REMOVAL, OVERHAUL & INSTALLATION -
TRUCKS & RWD VANS - GASOLINE article.
7) On all models, release fuel pressure. See FUEL PRESSURE
RELEASE. Remove latch clip. Remove test equipment. Before reinstalling
fuel supply line, ensure fuel supply line fitting and fitting on fuel
rail are clean.
8) Lubricate fuel supply line fitting and fitting on fuel
rail with engine oil. Install fuel supply line on fuel rail.
9) Install latch clip into fuel rail, with latch clip fingers
pointing downward. Ensure latch clip is fully seated. Latch clip
fingers should extend downward below fitting on fuel rail when fully
seated.
10) Pull on fuel supply line to ensure fuel supply line is
fully locked on fuel rail. Reinstall negative battery cable. Start
engine and check for fuel leaks.

Fig. 1: Identifying Latch Clip & Installing Fuel Pressure Gauge
Courtesy of Chrysler Corp.
FUEL PUMP RELAY
On all models, if fuel pump relay or control circuit becomes
defective, a Diagnostic Trouble Code (FTC) may be stored in the PCM.
For additional information on diagnosis for fuel pump relay and
control circuit, see TEST TC-101A in SELF-DIAGNOSTICS - JEEP, TRUCKS &
RWD VANS article.
IGNITION CHECKS
NOTE: For ignition system spark testing and component testing, see
TEST NTC-2A in SELF-DIAGNOSTICS - JEEP, TRUCKS & RWD VANS
article.

* ONE GAUGE NOT OPERATING PROPERLY
OVERHEAD CONSOLE CONCERNS
* AVERAGE MPH/FUEL ECON INOPERATIVE OR WRONG (CMTC FAILS TO
RESPOND TO INSTRUMENT CLUSTER DIMMING, DISTANCE TO EMPTY
INOPERATIVE OR WRONG, ELAPSED TIME INOPERATIVE/WRONG, SWITCH
ON CMTC INOPERATIVE, TRIP ODOMETER INOPERATIVE/WRONG)
* CMTC DISPLAY SHOWS FAILED
* CMTC SEGMENTS FAIL TO LIGHT UP
* INCORRECT READING BEYOND +/- 5
* REPAIRING "OC" IN CMTC DISPLAY
* REPAIRING "SC" IN CMTC DISPLAY
POWER DOOR LOCK SYSTEM
* DOOR LOCK SWITCH FAILURE (PDL)
* DOOR UNLOCK SWITCH FAILURE (PDL)
* AUTOMATIC (ROLLING) DOOR LOCKS INOPERATIVE
* DOORS LOCK WITH KEY IN IGNITION & LEFT DOOR OPEN
* ONE OR ALL DOORS FAILING TO LOCK FROM ONE SWITCH (ONE OR ALL
DOORS FAILING TO UNLOCK FROM ONE SWITCH)
* REMOTE KEYLESS ENTRY PROBLEM
VEHICLE THEFT/SECURITY SYSTEM
* DOOR DISARM SWITCH FAILURE
* DOOR LOCK SWITCH FAILURE
* DOOR UNLOCK SWITCH FAILURE
* EEPROM CHECKSUM FAILURE
* INTERNAL ROM TEST FAILURE
* IDENTIFYING VTSS PROBLEMS
WINDSHIELD WIPER SYSTEM
* WIPER PARK SWITCH FAILURE
* INTERMITTENT WIPERS INOPERATIVE
* NO WIPER ACTUATION AFTER WASH BUTTON PUSHED
* WIPER SPEED SENSITIVE FEATURE INOPERATIVE
CHIME SYSTEM
CHIME INOPERATIVE WITH EXTREME COOLANT TEMPERATURE
NOTE: For connector terminal identification and wiring diagrams,
see BODY CONTROL COMPUTER - INTRODUCTION article. Perform
VERIFICATION TEST VER-1A after each repair.
CAUTION: Always turn ignition switch to OFF position prior to
disconnecting any module connector.
1) Using scan tool, actuate chime. If chime sounds, go to
next step. If chime does not sound, replace Central Timer Module
(CTM). CTM is located under left side of instrument panel.
2) Using scan tool, read Powertrain Control Module (PCM)
DTCs. If no engine coolant temperature related codes exist, go to next
step. If engine coolant temperature related codes exist, see
appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE section.
3) Due to difficult access of coolant temperature sensor, Oil
Pressure Switch (OPS) will be used to verify CCD bus message from PCM.\
Disconnect OPS connector. OPS is located near bottom of distributor.

circuit.
ONE GAUGE NOT OPERATING PROPERLY
NOTE: For connector terminal identification and wiring diagrams,
see BODY CONTROL COMPUTER - INTRODUCTION article. Perform
VERIFICATION TEST VER-1A after each repair.
CAUTION: Always turn ignition switch to OFF position prior to
disconnecting or connecting any module connector.
1) Push and hold RESET button while cycling ignition key; ON-
OFF-ON. Instrument cluster self-test will start. If inoperative gauge
reached proper calibration point, go to next step. If inoperative
gauge did not reach proper calibration point, replace instrument
cluster.
2) Stop instrument cluster self-test. If problem is with
speedometer, go to next step. If problem is with oil pressure gauge,
go to step 5). If problem is with temperature gauge, go to step 14).
If problem is with fuel level gauge, go to appropriate SELF-
DIAGNOSTICS article in ENGINE PERFORMANCE section and review
powertrain symptoms. If problem is with volt gauge, go to step 16). If
problem is with tachometer, go to step 18).
3) Using scan tool, select BODY, SYSTEMS TESTS then PCM
MONITOR. If scan tool displays PCM ACTIVE ON BUS, go to next step. If
scan tool does not display PCM ACTIVE ON BUS, go to appropriate
VEHICLE COMMUNICATIONS article.
4) Raise and support all wheels. Start engine and place gear
selector in drive. Using scan tool, select MIC, MONITORS then CCD BUS
ENGINE INFO. Read VSS. If vehicle speed on scan tool matches
speedometer, see appropriate ANTI-LOCK BRAKE article. If vehicle speed
on scan tool does not match speedometer, replace instrument cluster
circuit board.
5) Turn ignition on. If CHECK GAUGES light illuminated, go to
next step. If CHECK GAUGES light did not illuminate, go to step 11).
6) Turn ignition off. Inspect oil level. If oil level is
within specification, go to next step. If oil level is not within
specification, adjust oil level and retest.
7) Turn ignition on. Disconnect engine Oil Pressure Switch
(OPS) connector. OPS is located near bottom of distributor. If CHECK
GAUGES light went out, go to next step. If CHECK GAUGES light did not
go out, go to step 10).
8) Remove OPS. Connect mechanical oil pressure gauge to OPS
port. Start engine. If engine oil pressure at idle is 4 psi or more,
go to next step. If engine oil pressure at idle is less than 4 psi,
repair mechanical engine problem.
9) Run engine to reach normal operating temperature. If
engine oil pressure at idle is 4 psi or more, replace OPS. If engine
oil pressure at idle is less than 4 psi, repair mechanical engine
problem.
10) Turn ignition off. Disconnect PCM White connector C2. PCM
is located in engine compartment on right inner fender. Using an
external ohmmeter, measure resistance between ground and PCM Black
connector terminal No. 23 (Gray/Orange wire). If resistance is less
than 5 ohms, repair short to ground in Gray/Orange wire. If resistance
is 5 ohms or more, replace PCM.
11) Disconnect engine Oil Pressure Switch (OPS) connector.
OPS is located near bottom of distributor. Using an external ohmmeter,
measure resistance between ground and OPS connector Black/Light Blue
wire. If resistance is less than 5 ohms, go to next step. If
resistance is 5 ohms or more, repair open Black/Light Blue wire.
Black/Light Blue wire is a common sensor ground. If no other engine
sensors are failed, repair ground between sensor and splice. If