Fuel Bowl Pump Diaphragm (proper installation) Before replacing the pump diaphragm cover, check for warpage by laying the cover on a sheet of emery paper which should be on a smooth surface. Remove the sealing bead, if any is present.
Place the diaphragm assembly on the cover, holding the pump lever arm against the diaphragm so that the diaphragm is flat. Don’t forget to install the spring into the bowl first. Install the cover and diaphragm on the fuel bowl and insert the screws finger tight.
Release the lever, making certain the diaphragm is loose enough to flex without wrinkling at the edges, also the diaphragm must be able to be raised so that the flange of the steel diaphragm washer touches the inner surface of the cover. These two checks will assure maximum diaphragm travel.
Tighten the four screws in two stages, 1/2 torque the first time and full torque on the final stage (5-8 lb. torque).