What Causes the Hand Primer Pump to Fail in Completely Removing Air?
1 Answers
Hand primer pumps fail to completely remove air due to air intake in the low-pressure fuel line and high-pressure gas backflow from the injector into the fuel supply line. Here are detailed explanations and solutions: Air intake in the low-pressure fuel line: Diesel runs out, creating a vacuum in the tank, which draws in air. The sealing gasket between the hand primer pump and the pump body on the fuel transfer pump is cracked or uneven. Severe wear of the hand primer pump piston or cup. Solution: Timely maintenance to ensure diesel remains at a safe level. Air intake in the low-pressure fuel line and high-pressure gas backflow from the injector into the fuel supply line: After the compression stroke of the diesel engine, at a certain angle before the piston reaches top dead center, the injector sprays diesel into the cylinder. At the moment the injector opens, the gas in the cylinder forms a pathway with the fuel line. If the injector quality is poor, high-pressure gas in the cylinder can flow back through the injector nozzle, sealing cone surface, gaps in the injector valve assembly, tappet hole in the injector body, and the injector return line into the diesel filter, eventually entering the fuel line. Solution: Remove the injector's main return line from the diesel filter, exposing it to the atmosphere, then block the return line hole on the diesel filter, purge all air from the fuel line, and restart the engine.
