Analysis of the reasons From the role of diesel fuel supply system shows that the diesel fuel supply should be based on a variety of engine requirements formulated a certain amount and concentration of combustible mixture to the cylinder, if the engine is not easy to start or start and turn off on their own, that Fuel supply system does not play a role in supplying a certain amount of diesel to the cylinder, and then analyzes the reason for insufficient or insufficient fuel supply. 1, the impact of low-pressure oil circuit (1) the impact of oil From the composition of the low-pressure oil we can see low-pressure oil in the series with a diaphragm pump, diesel filters, pressure limiting valve, oil to be smooth. If there is a blockage of mechanical impurities in the oil circuit or the pipe is bent, the oil supply is not enough to make the oil supply unblocked, or even not to supply oil. Low-pressure oil circuit is working under confined conditions, if there is a leak in the low-pressure oil circuit, it will cause insufficient oil supply, or even not oil. If the diaphragm pump suction section (from the tank to the diaphragm pump) seal is poor, the gas will be inhaled into the low-pressure oil, low-pressure oil vacuum decreases the impact of pump oil. As more gas is drawn in, less pump oil, or even oil. A leak in the diaphragm pump's pressure section (diaphragm pump to injection pump) will cause fuel injected into the injection pump to leak out of the circuit, and the amount of fuel that is fed to the injection pump is insufficient, or even not supplied. When the pressure-limiting valve is not closed properly, the amount of fuel returning to the oil circuit increases, so that the fuel input to the fuel injection pump decreases and the oil supply is insufficient. (2) the diaphragm pump diaphragm pump's role is: suck out the fuel tank of fuel and pressure to raise a certain pressure to the fuel pump. Its working principle is: the engine within the eccentric wheel top diaphragm pump rocker arm drive diaphragm up and down and make the volume change. When the pump oil pump chamber from small to large oil, from large to small external pressure oil. Pump diaphragm up and down repeatedly arching over time easy to produce fatigue cracks, severe rupture, so with the degree of failure of the diaphragm and reduce the amount of oil supply, or even not oil. 2, the impact of fuel injection pump The structure and working principle of the fuel pump shows that the injection pump should work according to the engine order, timing, quantitative, constant pressure fuel injector. The composition of the fuel injection pump is mainly composed of a driving mechanism, a secondary vane pump type oil pump, a high pressure pump head, a fuel supply amount adjustment mechanism and an oil supply advance angle automatic adjustment mechanism. If the engine does not even fuel oil shortage occurs, according to its composition and the role of each component to analyze the reasons for the failure to determine where. (1) the effect of vane pump Vane pump is used to accept the diaphragm pump delivery of diesel fuel, and increase the pressure to the fuel pump pressure pump, if the vane pump natural aging, pump function Recession or damage caused by insufficient or not oil supply. In addition, there is a pressure regulating valve in the low-pressure oil circuit, if the regulating valve is improperly adjusted or the valve is closed, it will also affect the oil supply. $$ Div $$ (2) Effect of Fuel Gauge Mechanism Fuel pump fuel quantity adjustment mechanism is used to adjust the fuel injection quantity. The adjustment principle is: the driver manipulates the accelerator lever (or pedal), through a series of transmission, the oil regulating sleeve in the distribution of the rotor shaft along the axial slip, near the distribution sleeve, the fuel supply increased Big. Conversely, when the driver relaxes the accelerator pedal, the oil control slide moves away from the distribution sleeve in the opposite direction to that described above, reducing the fuel supply. Oil control sliding sleeve and the distribution of rotor shaft axial and circumferential relative slip occurred, will inevitably produce friction and wear; oil control sleeve and the distribution of the rotor with the gap is to lubricate the fuel, although the fuel is filtered, but less than the filter The mechanical impurities of the core hole will still flow into the gap with the fuel to form abrasive wear. When the oil control sleeve and the distribution of rotor with the gap is too large, it will leak fuel injection cavity, thus affecting the fuel supply. When the sliding sleeve oil regulating mechanism of the parts or fuel control sleeve is mechanically stuck in a small amount of oil supply position, or even not in the fuel supply position, there will be insufficient fuel supply system, which does not supply oil. In addition, the electromagnetic cut off valve is used to connect or disconnect the fuel pump low pressure oil chamber and the fuel pump chamber. Its working principle is: When the driver starts the engine, turn on the ignition switch key, turn on the solenoid valve solenoid coil, the solenoid valve to generate electricity suction to overcome the spring force to pull the spool valve seat and then Through the oil path, when the power is off, the electromagnetic valve loses power and the suction force disappears. When the valve core is under the action of the spring, the spring extends to push the valve core to seated and close the oil path. If the solenoid valve coil is damaged or the circuit of the solenoid valve breaks, Solenoid valve does not produce suction, and cut off the oil, it is not oil. Oil shut-off lever is used to stop the fuel, so that the engine flameout. If the stopping device is mechanically stuck in the fuel supply is too small or not oil state, the fuel supply will be insufficient oil, or even not oil. (3) the impact of booster compensator Some axial compression pump without booster compensator. It is mainly composed of diaphragm, spring, valve body and valve. Its role is based on the size of the engine boost pressure, automatically increase or decrease the amount of fuel for each cylinder to improve engine power and fuel economy. When the engine is not working, the diaphragm archs up to the limit under the action of the spring and moves up to the limit position with the valve spool. The tilt lever of the valve core moves the compensation lever clockwise to rotate the oil-controlled tension lever clockwise and through Start the lever to move the oil control sleeve to the left to stop the oil supply. When the engine is working, the supercharging compensator is opposite to the above action under the pressure of the supercharged engine to increase the fueling amount. If the booster compensator diaphragm rupture or pressurized pipe leaks, will make the booster compensator appear as described above to reduce fuel supply or stop the fuel supply. (4) the impact of high pressure pump head The purpose of high pressure pump head is: to increase fuel pressure, fuel injector supply. The size of its high-pressure pump head fuel supply in addition to the amount of oil control agencies, but also with the high-pressure pump itself is good or bad and the distribution of rotor stroke related. If the high-pressure pump head seal is poor, fuel pump fuel supply with the corresponding degree of inadequate sealing inadequate. The function of the injection pump to distribute the rotor return mechanism is to rotate the cam plate together with the distribution rotor and return to the position under the action of the spring of the return mechanism after turning over the convex peak. If the return mechanism of the spring fatigue or broken, will affect the distribution of the rotor's fuel stroke. As a result, the impact of the injection pump fuel supply, that is manifested as insufficient oil, or even not oil. $$ Div $$ Diagnosis and troubleshooting Diagnostic failures are based on the principle of "easy first", "hard first" and "hard first". 1, if the engine is working, there is insufficient or no oil supply. Appearance check low-pressure oil leakage phenomenon. If there is leakage phenomenon, it is the fault, should be targeted to exclude oil spills. 2, if the engine is working well, it is very difficult to extinguish the fire before starting. Observe the flameout device, is still in the oil stop position, if it is the fault, you can pull it back to the fuel supply position, and to find out the cause of the flameout device can not automatically return, and then be excluded. 3, if the engine is suddenly off, you can check the fuel tank is oil. If the tank runs out of oil, should be added; if the tank is oil, should re-check the solenoid valve. The inspection method is: with a wire (instead of the original wire one end) lap the power supply, the other end lap electromagnetic disconnection valve FireWire connection column, if the engine can start, indicating the electromagnetic cut off valve wire breakage, otherwise, mostly due to electromagnetic off Oil valve coil damage, should be replaced with new parts. 4, check the turbocharger, remove the supercharger from the engine intake manifold, while blowing into the tube with the mouth, while starting the engine. If the engine can start, indicating the supercharger pressure is too small, should be ruled out. If there is a blow-by gas in the supercharger compensator pipe, it means that the gas pipe leaks or the diaphragm ruptures, proving that it is the cause of the problem of reducing or not supplying oil. Should then identify the situation and be excluded. 5, check the low-pressure oil circuit or exclude low-pressure oil air: (1) the pump low pressure into the pipe connector and hand pump oil, if not oil, is low pump oil is blocked or leak, and then check Filters or other places are clogged or leaks, to be ruled out to be excluded. (2) Use a wrench to loosen the oil return pipe on the fuel filter and pump the oil by hand. If you can see the large amount of oil return, it indicates that the pressure relief valve is not closed properly, which is the cause of insufficient oil supply. Strict reasons and be excluded. (3) Take out the oil dipstick, check the oil level and quality. If the oil level increases or the oil quality deteriorates, but also the engine start difficult, indicating that the diaphragm is more than the membrane pump rupture, the diaphragm pump should be removed to replace the diaphragm. 6, unscrew the top of the distribution sleeve plug, plug the hole by hand, pry the engine flywheel rotation, if the feel of the pressure is small or not obvious, it is mostly oil control sliding sleeve in the stop position, the fountain should be disassembled Oil pump identification, and be excluded. If there are conditions, you can also use the replacement method to find fault. Remove suspected parts and replace them with good parts. If troubleshooting, is the reason.