This instruction show you guide on how to diagnostic Doosan ISUZU 6UZ1 engine fuel rail/system pressure too low DTC P0087 error.
Related Contents:
ISUZU E-IDSS 2023 2019 Engine Diagnostic Service System Free Download
ISUZU IDSS MX2-T Diagnostic Tool
P0087 Diagnostics
1 Start the engine.
2 While checking the DTC with the trouble diagnosis scan tool, rev the engine a couple of times.
3 Check to see if the DTC P0087 is detected.
4 If the DTC P0087 is not detected, replace the fuel filter element.
Note: An intermittent problem due to foreign matter in the fuel is suspected.
5 Turn OFF the ignition switch.
6 Wait for the specified period of time until the fuel pressure is released from the common rail.
specified time： 2 min
7 Use the trouble diagnosis scan tool to check if the fuel rail pressure sensor data display is within the specified range.
values： 0.9 to 1.0 V
8 If the fuel rail pressure (FRP) sensor data display shows a value outside the specified range, inspect the fuel pressure sensor harness connector for poor connections
9 If a problem is found, repair the harness connector.
10 Inspect the ECM harness connector for poor connections.
11 If a problem is found, repair the harness connector.
12 Inspect each circuit for high resistance.
13 If a problem is found, repair the circuit.
14 If the harness connector and each circuit are normal, replace the fuel pressure sensor.
15 If the fuel rail pressure sensor data display is within the specified range, start the engine.
16 Perform the injector stop test with the trouble diagnosis scan tool.
17 Command each injector OFF, and confirm that the engine speed changes on each injector.
18 Check to see if any injector does not change the engine speed when OFF is instructed.
19 If any injector does not change the engine speed when OFF is instructed, replace the relevant injector.
20 When the injector has been replaced, set the injector ID code on the ECM.
21 Inspect to see if there is clogging with the fuel system between the fuel tank and the fuel supply pump.
22 If a problem is discovered, repair the clogging of the fuel system.
23 Inspect the fuel hose between the fuel tank and the fuel supply pump for a cut and crack.
24 If a problem is found, replace the fuel hose.
Note: The fuel hose between the fuel tank and the fuel supply pump becomes negative pressure state when the engine is running.
Note: When the fuel hose is not connected securely, the air can enter.
Note: When the engine speed or the engine load increases while the air has intruded in the fuel system, fluctuation in the common rail pressure is caused, and DTC P0087 may be detected.
25 Check that an appropriate clamp is used between the fuel tank and the fuel supply pump.
26 If a problem is found, replace the clamp.
27 Operate the priming pump until the handle becomes heavy.
Note: When a leak exists in the fuel system between the priming pump and the fuel supply pump, the pressing weight of the priming pump does not become heavy.
28 Start the engine.
29 Inspect the high-pressure side of the fuel system and check for fuel leak between the fuel supply pump and common rail.
Note: The fuel may leak under the cylinder head cover from the inlet of the high-pressure hose.
Note: The engine oil level increases when the fuel leaks to the bottom portion of the cylinder head cover.
Note: Inspect for fuel leaks into the engine oil.
30 If fuel leak if found, fix the problem.
31 Clear the DTC using the trouble diagnosis scan tool.
32 Turn OFF the ignition switch.
33 Connect another pipe to the supply pump inlet and perform a test-run while supplying fuel.
Note: Replace the fuel hose with a clear hose, and visually inspect for air intrusion.
34 If a problem is found, repair the cause of air intrusion.
35 Check the DTC using the trouble diagnosis scan tool.
36 When a DTC is not detected, inspect the fuel piping between the fuel supply pump and the fuel tank for damage and twisting.
37 If a problem is found, repair the fuel piping.
38 Check to see if there is any foreign matter in the fuel tank or any foreign matter which can cause fuel clogging.
39 If a problem is found, repair clogging.
40 When the fuel piping is normal without clogging, replace the fuel filter element
41 When a DTC is detected, check the actual fuel rail pressure data display with the trouble diagnosis scan tool.
42 Start the engine.
43 While checking the actual fuel rail pressure data display with the trouble diagnosis scan tool, rev the engine a couple of times.
44 While the engine is stopped, idling or revving check whether the actual fuel rail pressure display shows a value within the specified range.
Values:(-30) MPa {(-306) kgf/cm2 / (-4350) psi} When the engine is stopped
Values:(-5) to 5 MPa {(-51) to 51 kgf/cm2 / (-725) to 725 psi} When idling the engine and revving the engine
45 If the reading is within the specified range, inspect the fuel system between the fuel tank and the fuel supply pump for clogging.
46 If a problem is found, repair the fuel system.
47 Inspect the fuel hose for cuts and cracks.
48 If a problem is found, replace the fuel hose.
49 Inspect to see if appropriate clamp is used.
50 If a problem is found, replace the clamp with an appropriate one.
51 Turn OFF the ignition switch.
52 Inspect the PCV harness connector for poor connections.
53 If a problem is found, repair the harness connector.
54 Inspect the ECM harness connector for poor connections.
55 If a problem is found, repair the harness connector.
56 Inspect each circuit for high resistance.
57 If a problem is found, repair the circuit.
58When the PCV harness connector and the ECM harness connector are normal and no high resistance is found in each circuit, replace the fuel supply pump and the fuel filter element.
Note: When replacing the fuel supply pump, it is required to also replace the fuel filter element at the same time.
3 P0087 Confirm Resolution
1 Clear the DTC using the trouble diagnosis scan tool.
2 Turn OFF the ignition switch for at least 30 seconds.
3 Start the engine.
4 Perform a test-run.
5 Use the trouble diagnosis scan tool to confirm that a DTC has not been detected
More repair cases for ISUZU engine,please refer to:ISUZU Engine Trouble Repair