LI07.16-N-080732

Complaint The customer reports that the engine cranks but does not start, or only starts after extended cranking. A check engine light may be present, and fault codes P300616 (The fuel pressure in the system is too low) and/or P300617 (The fuel pressure in the system is too low) may be stored, along with other fuel pressure-related fault codes. Cause Insufficient high-pressure fuel build-up during engine cranking. The fuel system does not achieve the required rail pressure of >120 bar, preventing engine start. This condition may be caused by internal leakage within the fuel injection system, inadequate fuel supply from the low-pressure circuit, or a malfunction of the high-pressure fuel pump. Remedy 1. Verify high-pressure fuel rail pressure during engine cranking using XENTRY actual values.
• Evaluate the actual value “The starter turns and the combustion engine does not start” and monitor high-pressure fu-el rail pressure during cranking. (See attachment: XENTRY actual values – rail pressure not reaching >120 bar)
• The system must achieve a minimum of >120 bar in order to enable engine start. → If the specified rail pressure is not achieved, perform the following checks: 2. Check low-pressure fuel supply
• Verify fuel quality (color, clarity, separation, contamination)
• Inspect fuel tank, fuel filter, and low-pressure fuel pump for debris, restriction, or damage
• Measure low-pressure fuel supply before and after the fuel filter and confirm values are within specification
• Perform a fuel volume test at the high-pressure pump inlet to ensure adequate delivery
• Verify that the injector leak line is installed correctly, remains unmodified, and is not restricted or kinked → If low-pressure fuel supply is not within specification: Repair as necessary and recheck high-pressure fuel build-up 3. Check for internal leakage within the fuel injection system
• Perform a fuel injector leak/return test using XENTRY
• Evaluate injector leak-back during cranking NOTE: If the combustion engine does not start, perform the test by cranking the engine 3–4 times for approximately 15 seconds each, instead of allowing the engine to run for approximately 60 seconds → If injector leakage is present: Replace the affected injector(s) and perform injector teach-in 4. Check high-pressure fuel system
• If no leakage is identified and low-pressure supply is sufficient, evaluate high-pressure fuel generation → If high-pressure fuel system does not generate sufficient pressure: Replace the high-pressure fuel pump 5. Final verification
• Verify that rail pressure exceeds >120 bar during cranking
• Confirm the engine starts normally without extended crank
• Clear fault codes and perform final validation