All the geared manuals I have opened up have a open rear face over the roots gears with a sheet metal plate over the open face and inside the rear plastic cover. Some have had a small screw through the backside of the case and this would contact the center of that sheet metal plate. On occassion this screw would by either loosening or tightening a bit would allow a pump that no longer would prime to start working.

Many I see now have omited this screw making the pump with no possible adjustment.

The pump that has worked the best for me has been the hanger nine although these to have failed on me at times. I keep six cans gal/quart sizes all the time with different types of fuel with its own manual permanently secured to the can with RTV.


The OP's pump as he mentioned is an electric.


John