How to bleed air from the manual fuel pump

The diesel fuel-water separator is also called a diesel fuel filter, commonly known as: fuel filter element, filter cup, diesel filter, fuel strainer, manual fuel pump, etc.
Bleeding air and draining water from the fuel-water separator is also called: air in the low-pressure fuel system, bleeding air from the fuel system, bleeding air from the diesel filter, draining water from the fuel filter element, draining water from the filter cup, draining water from the diesel filter, draining water from the fuel strainer, draining water from the manual fuel pump; air in the vehicle's fuel system, pumping fuel with the manual fuel pump, etc.
Fault symptoms: Difficulty starting the engine, unstable engine operation, easy stalling while driving, and the water in fuel indicator light is on.
I. Air and fuel in the high-pressure fuel system (from the injection pump to the injector lines) can be removed automatically by cranking the engine with the starter motor. Do not loosen the pipe connection nuts at the fuel pump end, fuel rail end, and injector end to avoid high-pressure injury.
II. Air and fuel in the low-pressure fuel system (from the fuel tank to the fuel transfer pump) can be removed using the following method:
Fuel-water separator air bleeding procedure:
1. Park the vehicle in a safe, level place and open the fuel tank cap;
2. Locate the fuel-water separator and unscrew the air bleed bolt on the top of the filter element counterclockwise (usually an Allen bolt);
3. Operate the manual fuel pump handle back and forth about 30 times until fuel overflows from the air bleed bolt without bubbles.
4. Quickly and carefully tighten the air bleed bolt clockwise (see step 2 diagram).
5. After bleeding the fuel system, start the engine.
6. If the engine does not start within 10 seconds, repeat steps 2 to 4.