Insufficient fuel supply to the carburetor can be caused by a malfunctioning fuel pump or clogged or damaged fuel lines. To determine the cause of the malfunction, disconnect the hose from the pump discharge pipe and use the manual priming lever to check that fuel is being supplied. If fuel is not supplied, check the vacuum in the suction pipe. If there is no vacuum, the fuel pump is faulty.
The fuel pump can be checked on the stand. During rotation of the stand roller, having an eccentricity of 1.25±0.02 mm, with a frequency of 2000±40 min-1, the fuel supply must be at least 54 l/h at 20±5°C. The discharge pressure at zero fuel supply should be 2.2-3°m of water. Art.
Wash all parts of the disassembled pump with gasoline and blow with compressed air. Check the elasticity of the diaphragm spring, which should be compressed to 24 mm under a force of 3.2 kgf. Check the integrity of other springs and parts. Cracks and breaks of body parts are not allowed. The suction and discharge pipes must not rotate in their seats or have axial play. Diaphragms must not be torn, peeled or hardened. Diaphragm holes for pinch screws must not be protruded. Replace damaged parts with new ones.