Symptom: a 03 Beijing Hyundai Elantra car due to the car to send factory maintenance, the initial test by the idle speed stability, slow acceleration of normal, driving a car, to accelerate the phenomenon of lack of power.
    Fault diagnosis: from the phenomenon of failure like a high-speed fire or fuel system acceleration caused by insufficient oil pressure, in order to carefully call the fault code, the results of no code, read the data flow of the operating parameters are within the normal range, The possibility of a larger problem, then the oil pressure gauge to check the idle pressure of 320kPa (standard 310kPa ~ 340kPa), to accelerate the oil pressure gauge pointer has a slight downward trend, it is this small fluctuations caused our attention, The initial determination for the poor fuel supply, because this car has no fuel circuit with the fuel system, but it causes poor fuel supply for no more than four reasons: ① lack of pump; ② poor oil; Pressure regulator return oil is too large; ④ pump operating voltage is insufficient. According to the idea of ​​Jane Jane after the first in the back seat to find the next pump plug, with a multimeter to measure its operating voltage (not no-load voltage), 13.5V seems to be the problem is not working on the pump voltage, and then remove the pump, There is a layer of dirty material on the filter, and there is a small layer of dirty water tank, it is estimated that the cause of poor fuel supply is because the filter is dirty, with the car driving bumps while part of the dirty water into the oil, the mixture quality Poor, resulting in driving in the car, to accelerate the phenomenon of lack of power, remove the filter to its serious cleaning, replace the filter at the same time on the tank thoroughly cleaned, installed after the test, driving the car improved, faster than before Strong, but the total feeling or powerless, further analysis that, because the pump work in the dirty dirty filter conditions, long-term high-load operation, exacerbated the pump wear, resulting in pump power shortage, replace a new pump, Test, fault completely ruled out.
    Fault Summary: This car due to poor fuel supply, as well as dirty water tank caused by driving in the car, lack of power failure phenomenon in the car failure caused by the oil circuit is indeed a lot of trouble, as a maintenance staff we not only To read the number of pressure gauges, the key is that we will observe the changes in the indicators of the oil pressure gauge, and then to analyze the causes of change, the car driving a sense of sitting, lack of power for many reasons, the system oil pressure detection is An important part of the system, the system is too high pressure caused by thick mixture, so that combustion is not complete, resulting in idle jitter fuel consumption increases, the system is too low pressure caused by the mixture is too thin, slow burning, resulting in cold Start, idle instability, lack of power, and even produce tempering and other fault phenomena, in short, to make the engine normal combustion, there must be a stable oil pressure on the premise that the ECU can accurately control the fuel injection, and air to form a suitable air Fuel ratio to ensure the normal work of the engine.
    This car uses a non-return fuel system, which is different from the traditional electronic control engine fuel system, the traditional fuel pressure regulator are generally set in the engine fuel distribution pipe terminal, and the new non-return oil fuel system Generally, the fuel filter and the oil pressure regulator are placed in the fuel tank. As the traditional fuel system oil pressure regulator is close to the engine, and the average indoor temperature of the engine can be as high as 70 ℃ or more, the fuel will become steam at high temperature and make the oil The road to produce hot air resistance, so that the engine idle instability, acceleration and other poor, the system control of the oil pressure is to use manifold vacuum to meet the conditions in any case, can maintain the system pressure and manifold pressure difference Constant, so that the engine ECU accurate control of fuel injection, but the experiment proved that the engine room temperature is changed with the engine operating conditions, due to the fuel distribution pipe heat and gasification, so that the distribution of oil pressure fluctuations, Up to 65kPa, has exceeded the amount of change in vacuum regulation, that is, in addition to room temperature at other temperatures is difficult to ensure a constant pressure difference, and The new non-return oil fuel system eliminates the vacuum control, so that the system oil pressure regardless of what conditions are to maintain a certain pressure, because the electric fuel pump pump fuel for the fuel 5 to 7 times, so in the traditional Of the fuel system in the engine room heated fuel and a lot back to the tank so that the fuel tank fuel temperature increases, so that the phenomenon of air resistance in the oil is easy to occur, and no return fuel system to avoid the occurrence of this phenomenon , The fuel temperature in the fuel tank can be reduced by 15 ° C to 20 ° C, and the fuel leakage is reduced, the safety of the fuel supply system is improved, and the more optimized control of the fuel supply system is achieved, so that most of the current production Used by cars.