Jeep XJ. Manual — part 868
Symptom:
*ENGINE CRANKS DOES NOT START
POSSIBLE CAUSES
FUEL PUMP RELAY
NO START PRE-TEST
POWERTRAIN FUSES OPEN
FUEL PRESSURE OUT OF SPECS
RESTRICTED FUEL SUPPLY LINE
FUEL PUMP INLET STRAINER PLUGGED
FUEL PUMP MODULE
FUEL PUMP CAPACITY (VOLUME) OUT OF SPECS
FUEL PUMP RELAY FUSED B+ CIRCUIT
FUEL PUMP RELAY OUTPUT CIRCUIT OPEN
FUEL PUMP GROUND CIRCUIT OPEN/HIGH RESISTANCE
FUEL PUMP MODULE
TEST
ACTION
APPLICABILITY
1
Note: The following list of items must be checked before continuing with
any no start tests.
The battery must be fully charged and in good condition. A low charged battery may
produce invalid test results. If the battery is low, charge the battery and then attempt
to start the vehicle by cranking the engine for 15 seconds, 3 consecutive times.
This will allow any DTC’s to set that may have been erased due to a dead battery.
Ensure the Powers and Ground to the PCM are ok.
Make sure the PCM communicates with the DRBIII
t and that there are no DTC’s
stored in the PCM memory. If the PCM reports a No Response condition, refer to the
Communication category for the proper tests.
Read the PCM DTC’s with the DRBIII
t. If any DTC’s are present, they must be
repaired before continuing with any other No Start diagnostic tests. Refer to the
Symptom list for the related P-code that is reported by the PCM.
Ensure that the PCI bus is functional. Attempt to communicate with the Instrument
Cluster and SKIM, If you are unable to establish communicate refer to the
Communication category for the proper symptoms.
The Sentry Key Immobilizer System must be operating properly. Check for proper
communication with the DRBIII
t and check for DTC’s that may be stored in the
Sentry Key Immobilizer Module (SKIM). repair the DTC(s) before continuing.
If no DTC’s are found, using the DRBIII
t select Clear PCM (Batt Disconnect).
Crank the engine several times. Using the DRB, read DTC’s. If a DTC is present
perform the DTC diagnostics before continuing.
Were any problems found?
All
Yes
→
Repair as necessary.
Perform POWERTRAIN VERIFICATION TEST VER - 1.
No
→
233
STARTING
TEST
ACTION
APPLICABILITY
2
Check for any open fuses in the PDC or Fuse Block that may be related to the No
Start condition.
Are any of the fuses open?
All
Yes
→
Using the wiring diagram/schematic as a guide, inspect the
wiring and connectors, repair as necessary. Replace the Fuse.
Perform POWERTRAIN VERIFICATION TEST VER - 1.
No
→
3
Turn the ignition on.
With the DRBIII
t, actuate the ASD Fuel System test.
Note: It may be necessary to use a mechanics stethoscope in the next step.
Listen for fuel pump operation at the fuel tank.
Does the Fuel Pump operate?
All
Yes
→
No
→
Caution: Stop All Actuations.
4
Turn the ignition off.
WARNING: The fuel system is under a constant pressure even with the
engine off. Before testing or servicing any fuel system hose, fitting or line,
the fuel system pressure must be released.
Install a fuel pressure gauge to the fuel rail test port.
Turn the ignition on.
With the DRBIII
t, actuate the ASD Fuel System test and observe the fuel pressure
gauge.
NOTE: Fuel pressure specification is 339.2 KPa +/- 34 KPa (49.2 psi +/- 5 psi).
Choose a conclusion that best matches your fuel pressure reading.
All
Below Specification
Within Specification
Above Specification
Replace the fuel filter/fuel pressure regulator.
Perform POWERTRAIN VERIFICATION TEST VER - 1.
Caution: Stop All Actuations.
234
STARTING
*ENGINE CRANKS DOES NOT START —
Continued
TEST
ACTION
APPLICABILITY
5
Turn the ignition off.
WARNING: The fuel system is under a constant pressure even with the
engine off. Before testing or servicing any fuel system hose, fitting or line,
the fuel system pressure must be released.
Raise vehicle on hoist, and disconnect the fuel pressure line at the fuel pump module.
Install special 5/16
9 fuel line adapter tool #6539 between disconnected fuel line and
the fuel pump module.
Attach a fuel pressure test gauge to the
9T9 fitting on tool #6539.
Turn the ignition on.
With the DRBIII
t, actuate the ASD Fuel System test and observe the fuel pressure
gauge.
NOTE: Fuel pressure specification is 339.2 KPa +/- 34 KPa (49.2 psi +/- 5 psi).
Is the fuel pressure within specification now?
All
Yes
→
Repair/replace fuel supply line as necessary.
Perform POWERTRAIN VERIFICATION TEST VER - 1.
No
→
Caution: Stop All Actuations.
6
Turn the ignition off.
WARNING: The fuel system is under a constant pressure even with the
engine off. Before testing or servicing any fuel system hose,fitting or line,
the fuel system pressure must be released.
Remove the Fuel Pump Module and inspect the Fuel Inlet Strainer.
Is the Fuel Inlet Strainer plugged?
All
Yes
→
Replace the Fuel Pump Inlet Strainer.
Perform POWERTRAIN VERIFICATION TEST VER - 1.
No
→
Replace the Fuel Pump
Perform POWERTRAIN VERIFICATION TEST VER - 1.
7
Note: The fuel pressure must be within specification before continuing.
Turn the ignition off.
WARNING: The fuel system is under a constant pressure even with the
engine off. Before testing or servicing any fuel system hose, fitting or line,
the fuel system pressure must be released.
Disconnect the fuel supply line at the fuel rail.
Connect fuel line adapter #6539(5/16
9) or #6631(3/89) to the disconnected fuel supply
line. Insert the other end of the adapter into a graduated container.
Caution: Do not operate the fuel pump for more than 7 seconds in the next
step. Fuel pump module reservoir may run empty and damage to the fuel
pump will result.
Note: Specification: A good fuel pump will deliver at least 1/4 liter (1/2 pint)
of fuel in 7 seconds.
Turn the ignition on.
With the DRBIII
t, actuate the ASD Fuel System test for 7 seconds.
Is the fuel pump capacity within specification?
All
Yes
→
No
→
Check for a kinked/damaged fuel supply line between the fuel
tank and fuel rail. If OK, replace the fuel pump module.
Perform POWERTRAIN VERIFICATION TEST VER - 1.
Caution: Stop All Actuations.
235
STARTING
*ENGINE CRANKS DOES NOT START —
Continued
TEST
ACTION
APPLICABILITY
8
The following items need to be checked as a possible cause for a no start condition.
Refer to any Technical Service Bulletins that may apply to the symptom.
The spark plugs must be free from fuel, oil, coolant and/or any foreign material or
deposits.
The fuel must be free from contamination.
The exhaust may be free from restrictions.
The engine compression must be within specifications.
The engine valve timing must be within specifications.
The engine must be free from vacuum leaks.
Were any of the above conditions found?
All
Yes
→
Test Complete.
No
→
Test Complete.
9
Turn the ignition off.
Disconnect the fuel pump module harness connector.
Turn the ignition on.
With the DRBIII
t, actuate the ASD Fuel System test.
Using a 12 volt test light connected to ground, probe the Fuel Pump Relay Output
circuit at the Fuel Pump Module harness connector.
Does the test light illuminate brightly?
All
Yes
→
No
→
Caution: Stop All Actuations.
10
Turn the ignition off.
Disconnect the Fuel Pump Module harness connector.
Note: Check connectors - It is critical that the connector is free from any
signs of corrosion or deformities - Clean/repair as necessary.
Using a test light connected to battery voltage, probe the Fuel Pump ground circuit
at the Fuel Pump Module harness connector.
Does the test light illuminate brightly?
All
Yes
→
No
→
Repair the open/high resistance in the fuel pump ground circuit.
Perform POWERTRAIN VERIFICATION TEST VER - 1.
11
If there are no possible causes remaining, view repair.
All
Repair
Replace the Fuel Pump Module.
Perform POWERTRAIN VERIFICATION TEST VER - 1.
12
Turn the ignition off.
Remove the Fuel Pump Relay from the PDC.
With a 12 volt test light connected to ground, probe the Fuel Pump Relay Fused B+
circuit at the PDC.
Does the test light illuminate?
All
Yes
→
No
→
Repair the Fuel Pump Relay Fused B+ circuit. Check for open
fuse in the PDC.
Perform POWERTRAIN VERIFICATION TEST VER - 1.
236
STARTING
*ENGINE CRANKS DOES NOT START —
Continued
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