How to Check and Install the Fuel Injector

From：http://www.sinocmpinjector.com

If possible, the fuel injector can be directly installed on the fuel injector test bench for test and inspection according to the specified requirements. If there is no fuel injector test bench, it can be directly checked and adjusted on the diesel engine according to the following two methods provided by Yatong electromechanical:
(1) first prepare a standard injector (the injector) that meets the requirements of the injection pressure and the spray quality after checking and adjusting, and a three way connector, and install it on the oil outlet valve joint of the fuel injection pump (the fuel injection pump must supply normal).Put the throttle at the maximum oil supply position, reduce the pressure of the diesel engine, rotate the crankshaft at the speed of 100-200 R / min, and compare the standard injector with the inspected injector.

If the standard injector and the tested injector are injected at the same time, the atomization is good, the injection sound is clear and there is no oil dripping, it means that the injection pressure and atomization quality of the tested injector are qualified. If the tested injector injects fuel first or later than the standard injector, it means that the injection pressure of the tested injector is low or high. Adjust it, screw in or back off the pressure regulating screw until the tested injector is the same as the standard injector. If the two injectors inject oil at the same time, and the fuel atomization of the detected injector is poor, there is oil beam or oil drop, it means that there is a problem with the detected needle valve coupling, which needs to be repaired or replaced.

(2) If there is no standard injector and tee joint on hand, it can also be directly checked and adjusted on the diesel engine. The specific methods are as follows:

A. Remove the high-pressure oil pipe on the diesel engine, install one end of the high-pressure oil pipe on the oil inlet connector of the tested injector, one end on the oil outlet valve connector of the injection pump, and tighten the joint nuts at both ends of the high-pressure oil pipe;

B. Place the throttle handle at the maximum oil supply position. Under the normal oil supply condition of the fuel injection pump, rotate the crankshaft to make the diesel engine rotate within 100-200 R / min. at this time, the detected fuel injector injects fuel outside the cylinder to observe its atomization;

C. Turn the pressure regulating screw with a screw driver to make the injection pressure from low to high and the injection pressure from high to low. Repeat for 2 to 3 times. Select a place with good atomization quality, no oil beam, simple oil cut-off and no oil dripping. Fix the pressure regulating screw and continue to use. If the injector atomizes poorly all the time in the process of screwing the pressure regulating screw, there is oil spray, no injection sound and oil dripping, it means that the needle valve coupling of the injector cannot be used, and it should be replaced with a new one.

Before assembling the fuel injector, all parts must be cleaned thoroughly, especially the antirust oil on the new needle valve coupling parts. Precision parts must be washed in clean diesel and cannot be wiped with cotton. When installing, first install the parts on the upper part of the fuel injector body, i.e. ejector pin, spring, pressure regulating screw and other components. Note: do not tighten the pressure regulating screw at this time. After the upper part is installed, install the parts of the lower part of the fuel injector, the needle valve coupling and the fuel injector tightening cap. During installation, the pressure adjusting screw must be loosened first, and then the pressure screw can be adjusted after the fuel injection nozzle is installed and the combination nut is tightened. When correcting the injection pressure, it must be done on the injector calibrator. It is not allowed to test the injection pressure with the palm of your hand, which will be easily injured by the oil beam.

When the fuel injector is installed on the diesel engine, it is necessary to check in advance that the support shoulder of the mounting hole of the fuel injector shall be free of any nicks or cracks. Check again whether there are carbon deposits and stains left in the seat hole. If there is any, it must be cleaned thoroughly. Otherwise, the pressure of the fuel injector will not be tight, and the high-temperature and high-pressure gas will be ejected from the gap to burn the fuel injector, thus greatly reducing the service life of the fuel injector.

When installing the fuel injector on the engine, carefully check the height of the fuel injector protruding from the bottom of the cylinder head. If it is found that the installation height does not meet the specified requirements, the conical washer can be removed, and the appropriate gasket can be added between the fuel injector fastening screw sleeve and the conical washer body for adjustment, or the conical washer can be replaced. If it is found that the contact between the conical washer and the installation hole of the cylinder head is not tight, the conical washer can be removed by heating first and then cooling, so that its hardness can be reduced before installation. Before installation, use a special reamer to carefully remove the carbon deposit in the seat hole, so as to ensure that it is firmly fixed during installation. When tightening the two bolts of the fuel injector, make sure to use even force, otherwise it will easily cause the fuel injector to be skewed and incorrect, which will cause the engine to leak air or inject fuel outwards during operation.

How to Adjust Cummins Engine Injectors and Valves

From: http://www.sinocmpinjector.com

The Cummins engine uses its unique PT fuel system. The injector controls the fuel entering the cylinder. The valve controls the intake and exhaust valves of the engine. At the same time, the adjustment of the injector and the valve are interrelated in the adjustment sequence and method. of. Only when these two adjustments are properly made can the engine operate normally. Taking the NT(A)855 and KT(A)-1150 engines applied to construction machinery as an example, two methods for adjusting the valve of the injector are introduced.

1. Torque method The NT (A) 855 engine with a large cam non-stop injector is taken as an example to introduce the torque adjustment method.

Adjustment requirements

See Table 1 for the technical requirements for the adjustment of the injectors and valves of the NT(A) 855 engine.

Table 1: Adjustment parameters of injectors and valves for NT(A) 855 engine

Oil temperature Injector plunger adjustment torque N.m  Valve clearance mm

Aluminum rocker chamber Cast iron rocker chamber 

Oil temperature	Plunger adjustment torque N.m		Valve clearance mm
	Aluminum rocker chamber	Cast iron rocker chamber	Intake valve	Exhaust valve
Cold	8.0	5.4	0.28	0.58
Heat	8.1	8.1	0.28	0.58

First determine whether the engine uses a cast iron rocker arm chamber or an aluminum rocker arm chamber.

1 Loosen the lock nut of the injector rocker adjustment screw for all cylinders.

2 Twist the engine in the direction of engine rotation (right-handed) so that the mark A or 1-6VS (B or 2-5VS, C or 3-4VS) on the pulley is aligned with the arrow on the gear chamber cover.

3 Check the valve rocker arm of the I and VI cylinders (II and V, III and IV) to which the pulley mark is aligned. The valve of one cylinder must be closed, which is the cylinder that should be adjusted.

4 Adjust the injector plunger. Tighten the injector adjustment screw until the plunger contacts the nozzle cup, then screw in 15° to squeeze out the fuel in the cup; repeat twice to ensure that the fuel in the cup is completely squeezed; remove the adjustment screw Ring, use a torque wrench and a screwdriver to tighten the adjusting screw according to the adjustment requirements, and then tighten the lock nut with a torque of 54 ~ 61N.m.

5 Adjust the T-plate so that the gap between the nail plate and the valve spring seat is at least 0.51mm.

6 Adjust the valve clearance. Loosen the lock nut, exit the adjustment screw, put it between the rocker arm and the nail platen with the feeler gauge, then screw in the adjustment screw until the rocker arm just touches the feeler gauge, and then lock the adjustment screw with the torque of 54~61N.m. Tight nut.

7 Continue to turn the engine and adjust the remaining cylinders in the same steps. When applying the torque method adjustment, it should be noted that the valve of the same cylinder should be adjusted immediately after adjusting the injector of one cylinder, but it is not allowed to adjust the valve after adjusting the valve.

2. Thousands of points means that the dial gauge method is a method to adjust the injector plunger stroke to achieve correct adjustment.

The plunger stroke must be adjusted to the specified value. Here, the adjustment of the KT (A)-1150 engine is taken as an example to introduce this method.

(1) Adjustment requirements The adjustment requirements for KT(A)-1150 engine injectors and valves are shown in Tables 2 and 3, respectively.

(2) Adjustment method

1 Twist the engine in the direction of rotation until the mark A on the pulley is aligned with the arrow on the gear chamber. In this position, the valves of the V-cylinder are closed, and the injector plunger of the III-cylinder is at the top of the stroke. If not, the engine crankshaft should be turned 180° and realigned with the arrow. When the engine is turned around, no fan can be used to turn the engine, and a specially designed engine shaft is used. In the process of marking, any mark can be used as a starting point for adjustment, and it is not necessary to start with mark A.

2 Install the adjustment dial gauge correctly onto the rocker arm chamber so that the joint rod contacts the top of the III cylinder injector plunger.

3 Loosen the lock nut of the adjusting screw, screw in the adjusting screw, squeeze out the fuel in the oil cup, then exit 1/2 turn, carefully screw it to the bottom to ensure that the injector plunger contacts the bottom of the fuel injector cup. Tighten the adjusting screw too much. Set the dial indicator to zero.

4 Slowly retract the adjustment screw until the dial gauge reads 7.72 mm, then tighten the lock nut.

5 Press the injector plunger to the bottom with a rocker lever to check if the zero adjustment of the dial gauge is correct, then slowly pull the plunger back up and check if the dial gauge reading is within the adjustment requirements. After adjustment, tighten the lock nut with a torque of 41 to 47 N.m and remove the dial gauge.

6 Adjust the III cylinder injector and V cylinder valve; when adjusting the valve, the valve T-plate must be adjusted first. The adjustment clearance of the valve is shown in Table 2.

7 After adjusting the III cylinder injector and V cylinder valve, follow the same steps to adjust the remaining cylinders.

Note: When adjusting the injector and valve using the dial gauge method, never adjust the injector and adjust the valve on the same cylinder. It should be adjusted strictly according to the mark listed in Table 3 and the corresponding cylinder number of the injector and valve.

Table 2: Adjustment parameters of the KT(A)-1150 engine using the dial gauge method

Injector plunger stroke	Valve clearance
7.72±0.003	Intake valve	Exhaust valve
	0.36	0.69

Table 3: KT(A)-1150 engine injector and valve adjustment position

Turning direction	Pulley position	Adjust the nozzle cylinder number	Adjusting valve cylinder number
Start	A	III	V
Go to	B	VI	III
Go to	C	II	VI
Go to	A	VI	II
Go to	B	I	IV
Go to	B	V	I

Maintenance and Replacement Steps about Injectors

From：http://www.sinocmpinjector.com

C7 injector

The electronic unit injector is an important component of the
 fuel system of Caterpillar C4.4 C6.4 C6.6 engine and also a source of power. Valve damage: Generally caused by debris in the engine's fuel system, the damage is not due to component quality. The essence cause of the damage is debris in the engine's fuel system. To prevent damage from the fuel injector, please follow these guidelines.

When investigating a fuel system failure, follow the relevant troubleshooting steps before replacing any parts. Identify the source of fuel and, if necessary, analysis the fuel sampling . Check the application's maintenance records to ensure that all maintenance procedures are performed as per recommended
maintenance intervals. Before filling the fuel tank,

C9 injector

ensure the cleanliness of the fuel, no dirt and debris. Before filling the fuel tank, ensure the cleanliness of the fuel, no dirt and debris, the moisture inside the core needs to be released before ignition every day, and the filter element is recommended to use the original filter, because the quality of the deputy factory is not up to request, the fuel is not clean enough.

Correct maintenance steps:
1 discharge fuel tank deposits
2 discharge or clean fuel coarse filter is still in the water separator
3 Keep the fuel tank air intake smooth
4 replace the fuel filter
5 Check the cleanliness of the fuel system during maintenance or repairing. Because this fuel injector has extremely high requirements on fuel, it will be broken if you don't pay attention to it. Please also pay attention to timely maintenance.

 First, prepare a container for things and pour a little bit of diesel for cleaning. The first step is to remove the 6 high-pressure oil pipes, put them in the container, and then use the paper to block the common rail warehouse to prevent the dust. Then use a flat-blade screwdriver to remove the dust plug. Finally, remove the respirator screw in the venting door cover.

The outer part is removed. When the valve cover is opened, the injector can be seen, and then the screw on the injector is loosened, and the wire is removed. The injector can be removed by removing the injector fixing screw. Note! ! ! The key point is coming, when taking the injector, the injector fixing screw should be screwed on the injector with the tool, take the injector, take care not to remove the screws and other accessories inside the engine, once you fall in to be seen, use the iron rod to suck it out. If you can't see it, you can use it to flush it into the oil pan. You can remove it and find it in the engine. Otherwise, the engine will damage the internal parts of the engine as soon as it is working, resulting in overhaul of the engine. When the injector is removed and assembled, be sure to keep the injector clean, especially where the oil pipe is
connected.

Pay special attention to the oil inlet
It is not necessary to do this, it must be cleaned in the installation, otherwise it will easily cause the magazine to be flushed into the injector to cause damage.

Assembly steps:
1 Wash the injector cleanly and install
2 Install rubber sleeves
3 Install high-pressure oil pipes
4 Install wires
5 Install the valve cover
6 Fix the respirator. (Injector, rubber sleeve, oil pipe must be cleaned)
Finally, confirm that there is no problem, you can test the machine.

How to Detect and Evaluate the Performance of Bosch Truck Injectors

From: http://www.sinocmpinjector.com/

1. Whether the injection volume is accurate

According to the opening degree of the accelerator pedal, the amount of fuel injection is adjusted in time, which is the basic principle of the electronic control system. In order to achieve a good state of the engine's power performance, emissions performance, comfort performance, etc. the accuracy of the injector's fuel injection under different working conditions is very high. Generally, it is measured in mm3/stroke, that is, one-thousandth of a milliliter per injection.
There are several ways to assess the accuracy of the injection volume:
1) Static injection point
2) Dynamic injection curve
3) Spray repeatability, is standard deviation

2. Whether the leakage amount and functional oil return is normal

The leakage amount refers to the amount of oil that the high-pressure oil leaks into the low-pressure oil passage through the gap of each mechanical component. There are six main locations inside the CRIN injector, as shown in the following figure.
Functional oil return refers to the amount of oil that the injector returns from the high pressure oil passage to the low pressure oil passage to achieve its own injection performance. It is mainly returned to the armature by the valve seat control chamber through the seat of the valve seat when the injector ball valve is open. The amount of oil in the low pressure oil circuit around the assembly. During the after-sales test, the oil return (leakage + functional return) at the full load point is usually used as the assessment point.

3. Whether the jet delay is normal

The injection delay is the time interval between the start of energization of the electromagnet and the injection of fuel from the injector, typically between 300 and 800 microseconds. The level of rail pressure, the performance of the electromagnet, and the kinematics of each moving part will affect the jet delay.

4. Whether the spray atomization effect is good

The atomization effect of the fuel injection directly affects the combustion condition of the diesel oil and thus affects the working performance of the engine. The reason why the high pressure common rail system uses high pressure injection is to achieve a good atomization effect. Therefore, the level of rail pressure directly affects the atomization effect. In addition, the shape of the nozzle hole and the surface condition of the nozzle wall surface have a significant influence on the atomization effect (such as mechanical damage of the nozzle hole, surface erosion of the nozzle hole surface, particle wear, etc.).
It can be seen from the performance of the above Bosch truck injector that the performance of the injector is closely related to each component. Failure  of any component may cause the injector to lose effect as a whole, so during the maintenance process of injector, it is necessary to carry out systematic detection of each couple of injectors to find out the real cause of the fault, so as to eliminate them one by one and realize the maintenance effect and normal operation of the injector as soon as possible.