Troubleshooting methods include: disassembling the forward clutch, thoroughly cleaning the oil passages, and replacing the driving and driven friction plates and other damaged parts. Clean all relevant components and replace the outer sealing ring. Unblock and clean the check valve, and replace the clutch friction plates and inner and outer sealing rings.

If the excavator has difficulty starting, first check the battery power supply and fuel level. Additionally, check the electrical circuits and the connection of the engine starter wires to ensure a smooth start.

If the excavator lacks power and emits black smoke, stop working immediately to avoid further damage. Inspect the engine cylinders for damage and take appropriate maintenance measures.

If an excavator suddenly stalls while operating, it may be due to reasons such as low oil level, engine overheating, low coolant level, or overloading. Adjustments and checks should be made according to the specific situation, such as checking the oil level and replenishing it as needed, or adjusting the load to reduce overloading.

After normal use and parking, the engine could not be restarted, and no smoke was emitted. The starter motor worked normally, initially indicating a problem in the fuel system. When the manual fuel pump was used, the pumped fuel volume was sufficient, there was no air in the fuel flow, and the manual pump worked quickly. This indicated a normal fuel supply, no blockage in the fuel system, and no air leaks. Given the engine was relatively new, the fuel injection pump (with its seal intact) was unlikely to be faulty. Finally, the engine stop lever was found to be out of position; manually adjusting it allowed the engine to start normally. The fault was determined to be with the solenoid valve. Replacing the solenoid valve resolved the issue, and the engine started normally.