A 2008 modern Hyundai Car with a mileage of about 120 thousand km was slow to stall during the driving process and could not start. Troubleshooting and Troubleshooting: receiving the customer's distress call, the maintenance personnel bring the conventional tools to the scene. After the customer reflects, the vehicle is filled with oil in the first few days, driving a distance to extinguish the fire 7. according to the conventional inspection, open the ignition switch, try to start the engine many times, the start of the engine is strong rotation, can judge the battery capacity is sufficient. With enough fuel and electricity, why can't the engine start? From the circuit analysis, start the engine, listen carefully at the refueling port, hear the sound of the electric gasoline pump, you can judge the normal operation of the electric gasoline pump. Then from the oil path analysis, the fuel pressure gauge is installed in the fuel inlet pipe of the fuel distribution pipe to start the engine. The oil pressure is up to 295kPa when the oil pressure is highest, which is obviously lower than the standard value 343kPa of the oil pressure at the idling inlet, indicating that the electric gasoline pump can not provide enough oil pressure. Why does the electric gasoline pump work properly but can't provide enough oil pressure, check the maintenance manual and find that the fuel pressure regulator and the fuel filter are all installed in the tank, and will it be the oil pressure regulator leaking oil. Remove the rear seat and remove the electric fuel pump assembly. It is found that the fuel pressure regulator's tubing is not in place and the fuel filter has serious fouling on the surface. Re fixing the fuel pressure regulator and replacing the filter can start the engine and troubleshooting. Customers were told that the electric fuel pump assembly had been replaced in the first time and the oil was added at the private gas station. The main reason for this failure is that the fuel pipe clamps of the fuel pressure regulator were not carefully inspected when the fuel pump assembly was replaced, and the inferior gasoline was added. When the fuel filter is blocked, the oil pressure is too large and the gasoline is easy to leak from the oil pipe of the fuel pressure regulator, resulting in the insufficient pressure of the oil intake and the inability to start the engine.