Jeep Cherokee 2000 Service Manual - page 1237
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Black smoke from the exhaust
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Blue or white fog like exhaust
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Incorrect idle or maximum speed
The electronically controlled fuel pump has no
mechanical governor like older mechanically con-
trolled fuel pumps. Do not remove the top cover of
the fuel pump, or the screws fastening the wiring
pigtail to the side of the pump. The warranty of
the injection pump and the engine may be void
if those seals have been removed or tampered
with.
FUEL SUPPLY RESTRICTIONS
LOW–PRESSURE LINES
Restricted or Plugged supply lines or fuel filter can
cause a timing fault that will cause the ECM to oper-
ate the engine in a “Limp Home” mode. See the
introduction of the Fuel Injection System in this
group for more information on the Limp Home mode.
Fuel supply line restrictions can cause starting prob-
lems and prevent the engine from revving up. The
starting problems include; low power and blue or
white fog like exhaust. Test all fuel supply lines for
restrictions or blockage. Flush or replace as neces-
sary. Bleed the fuel system of air once a fuel supply
line has been replaced. Refer to the Air Bleed Proce-
dure section of this group for procedures.
HIGH–PRESSURE LINES
Restricted (kinked or bent) high–pressure lines can
cause starting problems, poor engine performance
and black smoke from exhaust.
Examine all high–pressure lines for any damage.
Each radius on each high–pressure line must be
smooth and free of any bends or kinks.
Replace damaged, restricted or leaking high–pres-
sure fuel lines with the correct replacement line.
CAUTION: The high–pressure fuel lines must be
clamped securely in place in the holders. The lines
cannot contact each other or other components. Do
not attempt to weld high–pressure fuel lines or to
repair lines that are damaged. Only use the recom-
mended lines when replacement of high–pressure
fuel line is necessary.
FUEL SHUTDOWN SOLENOID TEST
Refer to 2000 XJ 2.5L Diesel Powertrain Diagnos-
tic Manual for the Fuel Shutdown Solenoid test.
HIGH-PRESSURE FUEL LINE LEAK TEST
High–pressure fuel line leaks can cause starting
problems and poor engine performance.
WARNING: DUE TO EXTREME FUEL PRESSURES
OF UP TO 45,000 KPA (6526 PSI), USE EXTREME
CAUTION WHEN INSPECTING FOR HIGH–PRES-
SURE FUEL LEAKS. DO NOT GET YOUR HAND, OR
ANY PART OF YOUR BODY NEAR A SUSPECTED
LEAK.
INSPECT
FOR
HIGH–PRESSURE
FUEL
LEAKS WITH A SHEET OF CARDBOARD. HIGH
FUEL INJECTION PRESSURE CAN CAUSE PER-
SONAL INJURY IF CONTACT IS MADE WITH THE
SKIN.
Start the engine. Move the cardboard over the
high–pressure fuel lines and check for fuel spray onto
the cardboard (Fig. 20). If a high–pressure line con-
nection is leaking, bleed the system and tighten the
connection. Refer to the Air Bleed Procedure in this
group for procedures. Replace damaged, restricted or
leaking high–pressure fuel lines with the correct
replacement line.
CAUTION: The high–pressure fuel lines must be
clamped securely in the holders. The lines cannot
contact each other or other components. Do not
attempt to weld high–pressure fuel lines or to repair
lines that are damaged. Only use the recommended
lines when replacement of high–pressure fuel line
is necessary.
Fig. 19 Needle Movement Sensor Location
1 – NEEDLE MOVEMENT SENSOR
2 – FUEL INJECTOR (NUMBER 1 CYLINDER ONLY)
3 – COPPER WASHER
4 – SENSOR CONNECTOR
XJ
FUEL SYSTEM—2.5L DIESEL ENGINE
14 - 11
DIAGNOSIS AND TESTING (Continued)