One： circuit reason
The failure to start the car due to a circuit failure is mainly manifested in the fact that there is no response when turning on the ignition switch or the starting motor speed is too low, and it can feel weak. If these two phenomena occur, it can be roughly judged as a malfunction of the starting circuit. How to troubleshoot it?
1Check battery status
♥ Confirm the battery power status through the battery power observation hole. The blue color indicates that the battery power is normal, and the red color indicates that the power is insufficient. Check the circuit from the source, first check the battery pile head, clean the battery pile head, and then tighten the screw of the pile head. Qualified friends can use the multimeter voltage file to measure the battery voltage.
♡ If the battery is not faulty, check the circuit next, and check the battery circuit again to see if there is a broken circuit or a loose connector.
2 Check the relay fuse box
Check whether the connector is loose in the electrical box, and then open the fuse box to check whether the fuse of the starting circuit is burned out.
♧ The starter motor or generator failure can also cause the car to fail. Among them, the generator failure will cause the generator to not generate electricity normally, and the battery power cannot be replenished, resulting in low speed or no rotation of the starter motor.
Two： reasons for the oil circuit
If you can hear the starter motor turning vigorously after unscrewing the start key, and the engine does not have abnormal mechanical friction sound, then it is roughly judged to be the cause of the oil circuit. The oil circuit inspection of direct injection vehicles is simpler than the circuit, and it is more complicated to inspect some electronically controlled high-pressure common rail engines. Generally, you can check from the following steps:
1 Check if fuel is sufficient
First check whether there is oil in the fuel tank. A car with a good fuel gauge can observe the fuel tank volume through the fuel gauge.
2 Check whether the oil-water separator drains water
◇ After confirming that there is enough diesel in the fuel tank, the next step is to check the oil-water separator. Many people do not have the habit of draining water to the oil-water separator every day. If the quality of the oil that happens to be used is not high, it may not be able to start due to too much moisture in the diesel.
◆ The oil-water separator generally has a red buoy. The density of the buoy is between diesel and water, so it will float on the water and at the bottom of the diesel. When observing that the buoy of the oil-water separator is in the middle, unscrew the drain bolt at the bottom of the oil-water separator in time to release the water.
3 Check engine air emissions
● After removing the cause of excessive moisture in the diesel, if the vehicle still cannot be started, check whether the diesel is mixed with air.
○ First find the hand oil pump. Different brands of engine hand oil pump have different installation positions (some are installed near the diesel pump, and some are equipped with an electronic oil pump so there is no need to manually exhaust air. Most excavator hand oil pumps are installed above the oil-water separator). Loosen the bleed bolt next to the hand oil pump and press the hand oil pump by hand until the bleed bolt is all diesel oil, and then tighten the bleed bolt to complete the work of exhausting air.
Three： engine failure
There is no problem with the electric circuit and the oil circuit, then the engine may be faulty.
★ Generally, diesel engines have a relatively low probability of mechanical failure. Once a failure occurs, the engine must be overhauled. Common mechanical failures of the engine include cylinder pulling, tile burning, and cylinder ramming. Under normal circumstances, the mechanical failure of the engine is a precursor, for example, the engine suddenly runs weak during normal operation, or always emits black smoke, and there are abnormal noises during operation.
☆ Mechanical failures mostly occur when the engine is working. The probability of occurrence is low when a cold car is started. Generally, engine failures require lifting, disassembly, and maintenance. It is recommended to seek after-sales or professional maintenance personnel for repair.