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2006 ISUZU NPR.. CODE P0093 LARGE FUEL LEAK?? Can not WOT on…

Customer Question
2006 ISUZU NPR.. CODE P0093 LARGE...
2006 ISUZU NPR.. CODE P0093
LARGE FUEL LEAK??
Can not WOT on truck.. if you ease into the throttle your ok but if you WOT,it goes to limp mode with no pedal, erase code and back to normal until you WOT AGAIN.. any help pls advise
Submitted: 6 months ago.Category: Medium and Heavy Trucks
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Answered in 12 hours by:
8/2/2017
Technician: Andy, Truck Diagnostic Technician replied 6 months ago
Andy
Andy, Truck Diagnostic Technician
Category: Medium and Heavy Trucks
Satisfied Customers: 1,757
Experience: International and Isuzu trucks , International, Maxxforce, Cummins and Isuzu engines, Diagnostic and electrical troubleshooting specialist , Hvac and truck /trailer refrigeration troubleshooter
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Hi there . My name is***** also need the engine size please ? I will look this up for you later today if that's ok ?
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Customer reply replied 6 months ago
4HK1TC Diesel
Technician: Andy, Truck Diagnostic Technician replied 6 months ago
Thanks for the info ! Will get back to you today after work .
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Technician: Andy, Truck Diagnostic Technician replied 6 months ago

DTC P0093

Description

The common rail fuel system is comprised of two 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 fuel injectors. Fuel is drawn from the fuel tank via a feed pump and then pumped into the fuel rail by two plungers, all of which are internal to the fuel supply pump. This high pressure is regulated by the engine control module (ECM) using the fuel rail pressure (FRP) regulator dependant upon values from the FRP sensor attached to the fuel rail.

If the ECM detects that the fuel pressure is lower than desired value, this DTC will set. This most likely indicates some loss of fuel pressure or intermittently loss of fuel pressure by fuel leak from the high pressure side.

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Technician: Andy, Truck Diagnostic Technician replied 6 months ago

Condition for Setting the DTC

• The ECM detects that the difference of fuel leak quantity is larger than a threshold.

OR

• The ECM detects that the fuel rail pressure is dropped more than a threshold after an injection event compared with injection before.

OR

• The ECM detects that the fuel rail pressure is less than 18 MPa (2600 psi).

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Technician: Andy, Truck Diagnostic Technician replied 6 months ago

Action Taken When the DTC Sets

• The ECM illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.

• The ECM records the operating conditions at the time the diagnostic fails. The ECM stores this information in the Freeze Frame/Failure Records.

• The ECM limits fuel rail pressure within 11600 psi (80 MPa).

• The ECM limits accelerator control range to idle.

• The ECM closes the EGR valve and holds to close position.

• The ECM inhibits cruise control.

• The ECM inhibits PTO control.

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Technician: Andy, Truck Diagnostic Technician replied 6 months ago

Condition for Clearing the MIL/DTC

• The ECM turns OFF the MIL after 3 consecutive driving cycles that the diagnostic runs and does not fail. (12,000 lbs GVW)

• The ECM turns OFF the MIL that the diagnostic runs and does not fail. (Except 12,000 lbs GVW)

• A current DTC, Last Test Failed, clears when the diagnostic runs and passes after the key is cycled.

• A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic after the ECM turns OFF the MIL.

• Clear the MIL and the DTC with a scan tool.

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Technician: Andy, Truck Diagnostic Technician replied 6 months ago

Diagnostic Aids

• An intermittently sticking fuel rail pressure (FRP) regulator may have allowed the fuel pressure to drop suddenly.

• Normal Actual Fuel Rail Pressure readings on the scan with the engine running in Park or Neutral at idle are around 3650 to 5050 psi (25 to 35 MPa) and around 14500 to 21750 psi (100 to 150 MPa) in Park or Neutral at W.O.T. (accelerator pedal full travel).

• An intermittently sticking fuel injector may have allowed the fuel pressure to drop too much. Use a scan tool to perform the Cylinder Power Balance test for each injector. Verify a consistent engine speed change when commanding each fuel injector ON and OFF.

• A skewed FRP sensor value (shifted to a lower pressure) can set this DTC. The Actual Fuel Rail Pressure on the scan tool should read 0 psi (0 MPa) with the key ON and engine OFF after the engine has stopped running for a minimum of 2 minutes.

• Resistance in the FRP sensor low reference circuit can set this DTC. Ensure that the sensor low reference circuit has no resistance and the connectors are tight and free of corrosion.

Notice: This DTC most likely indicates loss fuel pressure by fuel leak from the high pressure side. Inspect the high pressure side fuel leakage between the fuel supply pump and fuel injector FIRST.

Notice: The Actual Fuel Rail Pressure on scan tool will only update with the engine running or one time after the key is cycled when the ignition has been turned OFF for longer than 10 seconds.

Notice: The fuel system from the fuel tank(s) to the fuel supply pump is under a slight vacuum with the engine running. As a result, air can enter the fuel system if these connections are not tight or if there is a crack in one of the fuel hoses. Air in the fuel system will cause fuel rail pressure fluctuations especially at high engine speed and load, which may set this DTC.

Notice: If the fuel tank is empty or near empty, air might be allowed to go into the fuel system. With air in the fuel system, smooth flow of fuel into the supply pump is interrupted and this DTC may set. Perform bleeding of fuel system after refilling.

Test Description

The numbers below refer to the step number on the diagnostic table.

7. This step checks for a fuel restriction by determining if a high vacuum is being pulled on the fuel system during normal operation.

8. This step checks for an air leak on the suction side of the fuel system by determining if a vacuum can be pulled when a fuel line is plugged.

DTC P0093

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Technician: Andy, Truck Diagnostic Technician replied 6 months ago

Hi there. I see you viewed my reply . Just checking in to see how it's going?

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Technician: Andy, Truck Diagnostic Technician replied 6 months ago

Happy to help if you need more assistance ! Looking for an update on this !

Please do not forget to accept my answer and rate my service at the end please ! Thank you !

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Technician: Andy, Truck Diagnostic Technician replied 6 months ago

Do you still need help with this ?

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Customer reply replied 6 months ago
Sorry about the delay an answering the response, I was on vacation. Iam going to get back to it tomorrow so I will advise what I find..
Thanks and talk soon
Technician: Andy, Truck Diagnostic Technician replied 6 months ago

Ok thanks for the update !

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Andy, Truck Diagnostic Technician
Category: Medium and Heavy Trucks
Satisfied Customers: 1,757
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Experience: International and Isuzu trucks , International, Maxxforce, Cummins and Isuzu engines, Diagnostic and electrical troubleshooting specialist , Hvac and truck /trailer refrigeration troubleshooter

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