Injector pump problem

Fuel injector working principle
The injector atomizes the diesel fuel and sprays it into the combustion chamber. The injector consists mainly of the nozzle and nozzle holder.
Possible causes of fuel injector pump faults:
A little or no fuel injected.
(1) There is air in the fuel supply system.
(2) Seizure of the fuel injector nozzle.
(3) Abnormal fuel supply from the fuel injection pump.
(4) Oil leak at high-pressure fuel pipes.
(5) Wear of fuel injector nozzles.
Too low fuel injection pressure.
(1) Lose pressure regulating screw.
(2) Deformation or break of the pressure regulating spring.
(3) Seizure of needle valves.
Too high fuel injection pressure.
(1) Pressure regulating spring force too high.
(2) Seizure of needle valves.
(3) Block of the injection holes.
Fuel leak at fuel injector.
(1) Break of pressure regulating springs.
(2) Damage of needle valve facing.
(3) Seizure of needle valves.
(4) Deformation of tightening cap.
(5) Poor contact between nozzle and injector body.
Poor fuel atomization
(1) decay of pressure regulating spring force or break of springs.
(2) Wear of fuel injector nozzle seat surface.
(3) There is impurity on the fitting plane of fuel injector nozzle assembly.
(4) Deformation or wear of nozzle assembly.
(5) Seizure of needle valve.
Helpful article recommended: https://www.dieselgeneratortech.com/diesel-engines/Engine-Governor-Fault-And-Fuel-Injector-Fault.html

Fuel filter, computer