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Uneven Fuel Supply of Injection Pump:Causes,Adjustment

Posted on 10/7/2018 11:59:46 AM

As we know,fuel injection pump is an vital component in diesel engine fuel injection system.Generally, the oil supply is adjusted on the test bench before installed for use.Even so, sometimes there will be power shortage, exhaust black smoke, unstable rotating speed anomalies.What we need to do is to analyze according to the different causes and then offer the related solution.Here injection pump parts manufacturer - China Balin Power Co.,Ltd will indicate two main reasons for the uneven fuel supply of injection pump and its adjustment.
 
1.The debugging state is different from the use condition
The injection pump is debugged on test bench at normal temperature while actually it is installed and used in  temperature of 500 ~ 500 ℃ in cylinder with pressure of 3 ~ 5MPa.When engine is working,the temperature of the fuel injection pump and injector are up to 90 ℃ or so,it will cause decrease in diesel viscosity,increasing internal leakage of plunger and needle valve couplings.The oil returned more than the time in debugging.According to the measurement, the actual oil injected into the cylinder of the injection pump is only about 80% of volume debugged on the test bench.Although the pump debugger will consider this factor,no one can master it accurately.Additonally,because the wear of cylinder piston and air distribution mechanism and difference of sealing,it results in that each cylinder compression temperature and pressure will also be different.So even the injection pump is debugged ready,the oil supply could also be uneven after installing.
 
2.Uneven oil supply during debugging
When the fuel pump is debugged on the test bench, the fuel supply unevenness of each cylinder at rated speed should be < 3%.In the actual debugging process,the customized test bench injector,and the lenth,shape,diameter of the high pressure pipes cannot be completely consistent with the original machine.On the other hand,the difference in debugging techniques,the actual inhomogeneity of oil injected into the cylinder is often > 3% after the installation of the fuel pump.
 
Adjustment after installing the pump 
1.According to the exhaust temperature, pressure or smoke color of each cylinder to determine its actual working conditions and the combustion degree of diesel engine.Thus determine the cylinder oil supply too much or too little, oil supply time too early or too late, and then adjust.By adjusting the quantity and time of the fuel supply of each cylinder, the fuel supply of each cylinder of the diesel engine is made according to the principle of distribution on demand, so as to eliminate the actual differences of each cylinder.
 
2.The operation techniques of oil pump readjustment
2.1 After the fuel pump is installed, the fuel supply time is adjusted according to the standard, and the exhaust manifold is unloaded at the same time, so as to observe the working conditions of each cylinder.
2.2 Start the diesel engine, idling for 2 ~ 3min, and touch the cylinder cover near the exhaust of each cylinder and the fuel injector by hand. If the temperature of a cylinder is too high, it can be preliminarily concluded that the oil supply of the cylinder is excessive.
2.3 When the engine temperature exceeds 50 ℃, step on the gas, to keep the engine running under the rated speed, check each vent smoked at the same time, listen to the voice of the cylinder.
2.4 If there is black smoke in a cylinder, it means that the oil supply is too large.Take 135 series engine for machinery as example,adjusting gear lever of the fuel injection pump can be pulled out to stop the oil, loosen the locking screw on the adjusting gear, take a thin iron rod and insert it into the hole of the oil control sleeve, tap it with a hammer to turn it to the right, then the oil supply can be reduced, otherwise increase.
2.5 When a cylinder has a crisp knock, and difficult to start, it means the oil supply started too early;If the temperature of a cylinder is on the high side, or even a flame ejection, it may be the reason of oil supply started too late.For the 135 series diesel engines, the starting time of each cylinder is adjusted according to the position of the pump plunger.When the oil supply starts too late, the diesel generator set should screw out the timing adjusting nut and screw a little bit. If the oil supply starts too early, tighten the screw a little bit.
2.6 Check the oil supply advance Angle
Generally, oil spill method can be used to check the oil supply advance Angle.Loosen the high-pressure oil pipe joint at the end of the oil pump, remove the joint at the end of the fuel injector, turn the oil pipe to a horizontal position, then tighten the high-pressure oil pipe joint of the oil pump, pull the throttle to a larger position, and open the decompression rocker until a few drops of diesel oil come out at the exit of the high-pressure oil pipe.Wipe the diesel oil off the end of the tubing and slowly turn the flywheel.At the same time, pay attention to the oil surface at the exit of the high-pressure oil pipe and stop rotating the flywheel at the moment when it starts to move.At this point, the water tank or on the body of the scribed line should be aligned before the flywheel check point between 16 ~ 20 °.If there is oil spill before they are aligned, it means the oil supply advance Angle is too large and oil supply too early.If there is an oil spill in excess,it means the oil supply is too late and the Angle of advance is too small.Diesel injection parts specialist - China Balin Power Co.,ltd notice that for multi-cylinder engines, special glass tube and pointer shall be installed to measure the arc length between two marks on the belt pulley of the fan when the front cylinder is being compressed at the top stopping point and the oil supply begins, so as to determine whether the oil supply advance Angle is correct.At the same time, check whether the oil supply interval of each individual pump is the same. If different, adjust the gap between the plunger and tappet or the thickness of gasket between the pump and the body to make the oil supply interval consistent.When the oil supply advance Angle is too small or too large, it needs to be adjusted.Different model has different adjustment methods.

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