MENGAMATI PENYEBAB DIESEL COMMONRAIL TIDAK HIDUP KARENA LOW PRESSURE

Summary

This video discusses troubleshooting diesel engine issues, specifically focusing on the common rail system. The presenter explains three examples of engine startup problems, analyzing battery voltage, engine speed, and fuel pressure data. In the first case, a low engine speed results in inadequate fuel pressure. The second case highlights a higher engine speed and sufficient fuel pressure, suggesting low compression as the issue. The third example examines a good engine speed but low fuel pressure, recommending further checks on the fuel system components like the supply pump and pressure limiter. The presenter concludes with troubleshooting tips to ensure proper engine function.

Takeaways

• 😀 A diesel engine may fail to start due to low fuel pressure, as indicated by low engine speed and low battery voltage.
• 😀 Battery voltage can remain at around 9-10 volts while the engine struggles to start, which indicates a functional battery but a possible engine issue.
• 😀 Low engine speed, like 139 RPM, leads to low fuel pressure, which is insufficient for proper engine operation.
• 😀 Despite normal current flow (around 1500 mA), low engine speed can indicate issues with components like bearings or the crankshaft, making the engine heavy to turn.
• 😀 A second example shows higher engine speed (around 200 RPM) and higher fuel pressure (37500 KPA or 375 bar), suggesting the injection signal is likely present.
• 😀 If fuel pressure is sufficient, but the engine still does not start, a possible cause could be low compression in the engine.
• 😀 In the third example, even with a good engine speed (225 RPM), there is no fuel pressure, indicating an issue with the fuel system.
• 😀 Even if the supply pump pressure and current to the SCV (Solenoid Control Valve) are adequate, the engine may fail to start due to issues in the fuel system.
• 😀 To check if the supply pump is functional, a conventional test can be performed with a set pressure of at least 300 bar to observe injector performance.
• 😀 If no fuel leaks from the return line during the test, it suggests the supply pump is working properly. Further inspection should focus on potential leaks in the injectors or the pressure limiter.

Q & A

What could be one of the main reasons a diesel common-rail engine doesn't start?

One possible reason is low fuel pressure in the system, which can prevent the engine from starting.

How can the battery condition be assessed while trying to start the engine?

By checking the battery voltage, if it’s around 9.10 volts, it indicates that the battery is still in good condition.

Why is the engine speed important when diagnosing engine start issues?

Engine speed is crucial because low RPM (e.g., 139 RPM) can indicate issues such as bearing or metal damage, which causes the engine to turn slowly and affects fuel pressure.

What does a low engine speed of 139 RPM signify in the context of engine diagnostics?

A low engine speed like 139 RPM suggests that there may be damage to the bearing or metal components of the engine, making it harder to start.

At what engine speed and fuel pressure can we expect proper fuel injection to occur?

When the engine speed is around 200 RPM and fuel pressure reaches 37,500 KPA (375 bar), proper fuel injection should occur, and the engine should start.

What could cause an engine not to start despite having adequate fuel pressure?

If fuel pressure is sufficient but the engine still doesn't start, it could be due to low compression or injector issues.

What diagnostic step can be taken if fuel pressure is still low despite good fuel system components?

One step is to install a conventional device on the supply pump and ensure it generates a minimum of 300 bar pressure. If fuel is injected, the pump is likely in good condition.

What does it indicate if fuel does not flow from the return line during engine startup?

If fuel does not flow from the return line during engine startup, it suggests a potential issue with the pressure limiter, which should be checked for leaks.

What should be done if the pressure limiter is confirmed to have no leaks?

If the pressure limiter is leak-free, the next step is to investigate the injectors for possible fuel leakage that could cause the loss of fuel pressure.

What additional checks should be made after confirming that the system from the fuel tank to the SCV is in good condition?

After confirming the fuel system is intact, further investigation should focus on possible issues with the supply pump, pressure limiter, or injectors to determine why fuel pressure is low.