Mercury 35/40HP 2 Cylinder Outboards Service Manual PN 90-42794--1, Page 54Get this manual
Fuel SystemTroubleshooting General Information
Problems, that are thought to be caused by the fuel systemmay be, in real ity, something completely differentItemsthat are shown in the list on the right, could give the impression that there is problem in the fuel system
T diagnose the fuel system, see theTrouble Chart," below
Propeller Spark plugs Ignition timing Ignition spark voltage Cylinder compression Reed valves