What are the main causes of engine speed drop?
2 Answers
Reasons for engine speed drop: It is caused by a fault in the diesel fuel system of the excavator. Generally, when the diesel fuel line is blocked, it is easy to cause a speed drop phenomenon. The hydraulic system of the excavator has malfunctioned, preventing the hydraulic pump from normally adjusting the displacement, resulting in excessive system pressure, speed drop, and simultaneous stalling. The excavator engine itself has insufficient power output, with the output power lower than the rated power and the speed too low. Another reason could be an issue with the main pump. The use of poor-quality fuel or fuel with high water content in the engine can lead to insufficient engine power, causing speed drop. When the intake system leaks or is blocked, it can cause insufficient air supply to the engine, resulting in incomplete fuel combustion, leading to speed drop and black smoke. Due to excessive clearance in the solenoid valve, insufficient fuel supply occurs, thereby causing engine speed drop. Loosened or ruptured fuel system supply line connections can cause fuel leaks or blockages by foreign objects, leading to insufficient fuel supply, which not only causes speed drop but also stalling. Solutions for engine speed drop: First, check whether the diesel used in the excavator has deteriorated or contains impurities, and inspect if the fuel line is blocked. Check the valve clearance of the excavator engine and the engine speed. Inspect the intake pipeline, clean the air pre-filter and air filter element, then restart the engine. Check whether the speed drop issue occurs under engine load conditions. Conduct a thorough inspection of the engine to determine if the speed drop is caused by engine failure.
I find engine stalling quite annoying, mainly due to fuel system issues. If the fuel injectors are clogged, gasoline can't spray out, and the engine 'starves'; or if the fuel pump isn't working properly, the low fuel pressure leads to insufficient power. Also, air intake leaks are quite common—like aging rubber hoses cracking, allowing air to leak in and disrupt the air-fuel mixture, making the engine 'gasp for breath.' The ignition system isn't blameless either—spark plugs with excessive carbon buildup from prolonged use or weak ignition coils can cause RPM drops. Some electronic faults, like a dirty oxygen sensor providing incorrect feedback data, can confuse the car's computer. To prevent these issues, avoid using low-quality fuel and regularly replace filters. I remember one time my car suddenly lost power—turned out to be an intake leak. A small repair cost later, and it was much safer.
