P0087-FUEL RAIL PRESSURE MALFUNCTION PRESSURE TOO LOW

For a complete wiring diagram Refer to Section 8W

When Monitored:
With the engine running.
Set Condition:
The ECM determines that the fuel rail pressure is too low for a given engine speed.

Possible Causes

AIR IN FUEL SYSTEM

FUEL DELIVERY SYSTEM CONCERNS

FUEL INJECTOR(S)

FUEL PRESSURE SOLENOID

FUEL PUMP

FUEL SYSTEM CONTAMINATION

FUEL SYSTEM LEAK

Diagnostic Test

1. CHECKING FOR OTHER ECM DTCS

WARNING: HIGH-PRESSURE FUEL LINES DELIVER DIESEL FUEL UNDER EXTREME PRESSURE FROM THE INJECTION PUMP TO THE FUEL INJECTORS. THIS MAY BE AS HIGH AS 23,200 PSI (1600 BAR). USE EXTREME CAUTION WHEN INSPECTING FOR HIGH-PRESSURE FUEL LEAKS.

WARNING: FUEL UNDER THIS AMOUNT OF PRESSURE CAN PENETRATE SKIN CAUSING PERSONAL INJURY OR DEATH. INSPECT FOR HIGH-PRESSURE FUEL LEAKS WITH A SHEET OF CARDBOARD. WEAR SAFETY GOGGLES AND ADEQUATE PROTECTIVE CLOTHING WHEN SERVICING FUEL SYSTEM.

Turn the ignition on.
With the scan tool, read the ECM DTCs.

Are there any other DTCs present?

Yes

Refer to symptom list for problems related to the DTC other than this DTC.

Perform the ECM Verification Test Ver. 1 (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).

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2. CURRENT DTC

NOTE: If the ECM detects and stores a DTC, the ECM also stores the engine/vehicle operating conditions under which the DTC was set. Some of these conditions are displayed on the scan tool at the same time the DTC is displayed.

NOTE: Before erasing stored DTCs, record these conditions. Attempting to duplicate these conditions may assist when checking for an active DTC.

NOTE: Refer to the Service Information and perform the Air Bleed Procedure before continuing diagnosis.

Turn the ignition on.
With the scan tool, erase the ECM DTCs.

NOTE: Driving the vehicle up and down steep hills or rapid cornering with a low fuel level can cause this DTC to set. Verify with customer if Low Fuel Light was illuminated when fault occurred.

Test drive the vehicle under various load and speed conditions to attempt to duplicate the fault.
With the scan tool, read the ECM DTCs.

Does the scan tool display this DTC?

Yes

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Refer to the *CHECKING FOR AN INTERMITTENT DTC Diagnostic Procedure. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)

3. FUEL SYSTEM LEAK

Turn the ignition off.

Inspect the entire fuel system for leakage.

NOTE: This vehicle is not equipped with an in-tank fuel lift pump. The high pressure fuel pump draws (vacuums) the fuel from the fuel tank. Even a very small leak in the fuel supply system between the fuel tank and high-pressure pump can cause driveability problems and dtc's to set.

Is there any evidence of leakage?

Yes

Repair as necessary in accordance with the Service Information.

Perform the ECM Verification Test Ver. 1 (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).

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4. FUEL SYSTEM CONTAMINATION

NOTE: Mixing any other fuels such as gasoline or kerosine can cause this DTC to set.

Turn the ignition off.

Refer to the Service Information and inspect the fuel system for contamination.

Is the fuel contaminated?

Yes

Repair as necessary in accordance with the Service Information.

Perform the ECM Verification Test Ver. 1 (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).

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5. ATTEMPT TO START ENGINE

Turn the ignition on.
With the scan tool, erase the ECM DTCs.
Attempt to start the engine.

Does the engine start and idle?

Yes

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6. CHECKING FOR AIR IN FUEL SYSTEM

Start the engine.
With the scan tool, compare the Fuel Pressure Setpoint with the Actual Fuel Pressure readings.

NOTE: If there is air in the fuel system, the Actual Fuel Pressure will oscillate more than 100 psi above and/or below the Fuel Pressure Setpoint.

Does Actual Fuel Pressure oscillate more than 100 psi above and/or below the Fuel Pressure Setpoint?

Yes

Refer to the Service Information to purge air from the fuel system.

Perform the ECM Verification Test Ver. 1 (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).

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7. FUEL PRESSURE SOLENOID

Start the engine.
With the scan tool, compare the Fuel Pressure Setpoint with the Actual Fuel Pressure readings.

NOTE: A sticking Fuel Pressure Solenoid is indicated by Actual Fuel Pressure gradually dropping below the Fuel Pressure Setpoint then suddenly increasing (spiking) above the Fuel Pressure Setpoint.

Does Actual Fuel Pressure gradually decrease then suddenly increase (spike) above the Fuel Pressure

Yes

Replace the Fuel Pressure Solenoid in accordance with the Service Information.

Perform the ECM Verification Test Ver. 1 (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).

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8. CHECKING FUEL DELIVERY SYSTEM

Refer to the appropriate Service Information and refer to Diagnosis and Testing Fuel Delivery System table.

NOTE: The following is a list of problems that can cause fuel pressure to deviate from specification: restricted fuel filter or fuel lines, failed fuel pressure solenoid, air in fuel system, failed fuel sending unit, contaminated fuel, faulty injector.

Were there any problems with the Fuel Delivery System?

Yes

Repair as necessary in accordance with the Service Information.

Perform the ECM Verification Test Ver. 1 (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).

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9. FUEL INJECTOR(S)

NOTE: An injector that sticks open can cause this DTC. A sticking injector will cause the engine to misfire and emit excessive black smoke from the exhaust system.

Start and idle the engine.

Does the engine exhibit the symptoms described in the above note?

Yes

Using the Service Information, remove and inspect the Fuel Injectors for signs of damage or debris that may cause the injector to stick. Sticking injectors may cause the combustion chamber to become black and oil soaked. Replace Injector(s) as necessary.