Mark the position of the pump cover relative to the housing.
Remove the cover and the suction valve. Check the operation and technical condition of the discharge valve.
Clean the pump from dirt and rinse it with a large amount of gasoline.
If the diaphragm is ruptured, replace it. To do this, remove the drive lever shaft, plate, drive lever and its return spring, and the diaphragm assembly.
Install a new diaphragm using tool 5125. The diaphragm must be installed horizontally, without tilting, and fit tightly against the housing.
Install the pump cover according to the previously applied marks.
(You can read the original on the website: www.bmwman.ru)