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Here is the instruction show you guide on how to solve ISUZU construction 4JJ1 engine P0089 fuel rail pressure regulator performance.
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P0089 DTC Information
DTC description
A typical common rail (fuel rail) system is composed of the following 2 fuel pressure sections: A suction side between the fuel tank and the fuel supply pump, and a high pressure side between the fuel supply pump and the injectors. The fuel is drawn from the fuel tank and then supplied to the common rail (fuel rail) by plungers that are located inside the fuel supply pump. The common rail (fuel rail) pressure is controlled by the ECM, which controls the FRP regulator based on signals from the FRP sensor. If the ECM detects that the actual fuel pressure is higher than the desired fuel pressure, the DTC is set.
Condition for setting the DTC
Preconditions
・The engine is running. ・DTCs P0091, P0092, P0192, P0193, P0201, P0202, P0203, P0204, P060B, P1261, P1262, P2146, and P2149 are not set.
Setting conditions
・The ECM detects that the common rail (fuel rail) pressure is more than the desired common rail (fuel rail) pressure by 40 MPa {408 kgf/cm2 / 5,800 psi} or more for 5 seconds or more.
Action taken when DTC sets
・Failure is indicated* in the monitor on the machine, or the diagnostic light illuminates.
Note: *Depending on the machine manufacturer, a failure may not be indicated.
・The ECM limits the fuel injection quantity. ・The ECM stops multi-injection.
P0089 Diagnostics
Note: If the machine runs out of fuel, air may be entered the fuel system. When there is air in the fuel piping, the smooth flow of fuel into the fuel supply pump is interrupted and this DTC may be set. Bleed air from the fuel piping after refilling the fuel.
OBD system check
Current DTC check
Connect a trouble diagnosis scan tool.
Turn OFF the ignition switch for 30 seconds or more.
Start the engine.
Observe the DTC information with a trouble diagnosis scan tool. Is DTC P0089 set?
Yes
⇒Go to Prioritized DTC check.
No
Go to Intermittent conditions of engine.
Prioritized DTC check
Observe the DTC information with a trouble diagnosis scan tool. Is DTC P0091, P0092, P0192, P0193, P0201, P0202, P0203, P0204, P2146, or P2149 set?
Yes
Go to the applicable DTC diagnosis.
No
⇒Go to DTC check when revving engine.
DTC check when revving engine
Turn OFF the ignition switch.
Start the engine.
Operate to increase the engine speed from idling speed to maximum speed while observing the DTC information on a trouble diagnosis scan tool. Is DTC P0089 set?
Yes
⇒Go to FRP sensor signal voltage check.
No
An intermittent problem due to foreign material in the fuel is suspected.
Replace the fuel filter element.
⇒Go to Repair verification.
FRP sensor signal voltage check
Turn OFF the ignition switch.
Wait for 2 minutes to reduce the fuel pressure of the common rail (fuel rail).
Turn ON the ignition switch.
Observe “Fuel rail pressure sensor” display on the trouble diagnosis scan tool. Is “Fuel rail pressure sensor” display within the specified value?
values： 0.4 to 0.5 V
Yes
⇒Go to Injector inspection.
No
⇒Go to FRP sensor circuit inspection.
Injector inspection
Start the engine.
Perform “Injector stop” with the trouble diagnosis scan tool.
Check whether the engine speed changes as each injector is turned OFF. Are there any injectors that do not change the engine speed?
Yes
Replace the injectors that do not change.
Note: If an injector has been replaced, be sure to set the Injector ID Code on the ECM.
Refer to 1C Fuel System(4JJ1) [injector removal] Reference
Refer to 1C Fuel System(4JJ1) [injector installation] Reference
⇒Go to Repair verification.
No
⇒Go to Fuel filter return pipe inspection.
Fuel filter return pipe inspection
Inspect for breakage or twisting in the fuel system between the fuel filter and the fuel tank. Is the result normal?
Inspect the fuel tank vent hose for clogging. Is the result normal?
If possible, inspect for foreign material in the fuel tank or for foreign material that may cause clogging of the fuel. Is the result normal?
Are all of the results normal?
Yes
⇒Go to FRP regulator circuit inspection.
No
Repair or replace as necessary.
⇒Go to Repair verification.
FRP regulator circuit inspection
Inspect for poor connections at the FRP regulator harness connector. Is the connection status normal?
Inspect for poor connections at the ECM harness connector. Is the connection status normal?
Inspect the circuit between the ECM and the FRP regulator for high resistance. Is the result normal?
Are all of the results normal?
Yes
⇒Go to Common rail (fuel rail) pressure check.
No
Repair the circuit or connection as necessary.
⇒Go to Repair verification.
FRP sensor circuit inspection
Inspect for poor connections at the FRP sensor harness connector. Is the connection status normal?
Inspect for poor connections at the ECM harness connector. Is the connection status normal?
Inspect the circuit between the ECM and the FRP sensor for high resistance. Is the result normal?
Are all of the results normal?
Yes
Replace the FRP sensor.
⇒Go to Repair verification.
No
Repair the circuit or connection as necessary.
⇒Go to Repair verification.
Common rail (fuel rail) pressure check
Turn OFF the ignition switch.
Start the engine.
Operate to increase the engine speed from idling speed to maximum speed while observing the “Actual fuel rail pressure” display and “Desired fuel rail pressure” display on a trouble diagnosis scan tool. Does the difference between the “Actual fuel rail pressure” display and the “Desired fuel rail pressure” display show a value within the specified range quickly enough?
Note: Compare with other vehicles having the same engine if possible.
values： -5.0 to 5.0 MPa { -51 to 51 kgf/cm2 / -725 to 725 psi }
Yes
An intermittent problem due to foreign material in the fuel is suspected.
Replace the fuel filter element.
⇒Go to Repair verification.
No
Replace the fuel supply pump.
Note: The fuel supply pump must be timed with the engine, and the ECM requires learning.
⇒Go to Repair verification.
Repair verification
Clear the DTC with a trouble diagnosis scan tool.
Turn OFF the ignition switch for 30 seconds or more.
Start the engine.
Perform a test-run under the conditions for running the DTC.
Observe the DTC information with a trouble diagnosis scan tool. A DTC should not be set.
More repair cases for ISUZU engine,please refer to:ISUZU Engine Trouble Repair
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