Basic USES of hand pumps:

When a diesel engine has air in its fuel duct, such as a new car that has just come off the line, or when the oil in the tank has run out, the engine cannot start when the engine is started, because the diesel fuel pump only works when the engine is started. It is then necessary to use a hand pump to pump the fuel pump in the tank into the tunnel. (First loosen the exhaust bolts on the fuel injection pump until the bubbles are exhausted)

Working principle of hand pump:

When the piston moves upward, the volume in the pump chamber expands to form a vacuum, and then under the action of the spring, one-way valve 2 closes. Under the action of atmospheric pressure, one-way valve 1 opens, and fuel enters the pump chamber through the inlet pipe.

When the piston moves downward, the oil pressure in the pump chamber rises, closing check valve 1 and opening check valve 2, the fuel is discharged from the outlet, and so on, the continuous oil transfer in the driving pump.