Inspection and troubleshooting of fuel injector

Inspection and troubleshooting of fuel injector

The inspection and adjustment of the fuel injector assembly at some service points are too extensive. Some only check and adjust the starting injection pressure, reducing some items that should not be simplified. This is incorrect. We think that the adjustment should be carried out according to the specification. Not only should we check and adjust the standard injection pressure, but also we should further check the spray cone angle and fuel quality according to the specific conditions, especially the tightness check of the injector should be paid more attention to.

Sealing inspection of fuel injector: it is carried out on the fuel injector tester. Take the porous long type fuel injector as an example, increase the preset pressure of the fuel injector tester to 23-24 MPa, and increase the fuel injector pressure to 24-25 MPa. When the pressure of the fuel injector tester drops from 20 MPa to 18 MPa, the duration of the standard fuel injector shall be 9-20 s, and the allowable use shall not be less than 9 s.

It should be noted that: first of all, the injector tester must meet the technical requirements, the high-pressure oil circuit should be tight, and the sealing of the oil outlet valve coupling on the tester itself should be good. Remove the air from the oil circuit, plug the high-pressure oil outlet joint, continue to supply oil and increase the pressure, so that the preset pressure rises to 23-24 MPa. When the pressure of the tester drops from 20 MPa to 18 MPa, the duration shall not be less than 3 minutes. Secondly, the fuel injector shall be inspected at least twice, and the average value shall be taken. And the difference between the two adjacent durations shall not be more than 2S for the axial pin and flat type, and not more than 3S for the porous long type.

Troubleshooting

After the needle valve and valve body of the injector are not tightly sealed, locked or dripped, the injector shall be removed first and the needle valve and valve body shall be cleaned with clean diesel oil. If there are slight pockmarks and pits on the sealing conical surface of the needle valve and the valve body, grind them on the special equipment or wire pliers (note that the grinding paste shall not enter the sliding surface of the needle valve and the valve body), and then grind them with engine oil until the pockmarks and pits on the sealing conical surface of the needle valve and the valve body disappear and appear black and bright. For the injector that the needle valve and the valve body are locked, take out the needle valve with the wire pliers first, and then put it into the clean diesel oil for cleaning, and then use the finer oilstone or sand bar to grind the stuck bulge flat (note that other parts shall not be abraded), so that the needle valve can slide freely in the valve body, and then use the grinding paste and oil to grind the sealing cone until the above requirements. If the pits and pits on the sealing cone of the needle valve and the valve body are too deep to be repaired, the new fuel injector shall be replaced, and the injection pressure and fuel atomization quality shall be adjusted on the test bench or vehicle to meet the use requirements.