1998 Honda VF750

MY 1998 HONDA MAGNA VF750 HAS SUFFERED A FUEL SYSTEM FAILURE DUE TO THE "AUTO FUEL VALVE". THE VEHICLE RUNS LEAN THROUGH MID-RANGE ENGINE SPEEDS AND LOSES POWER. EVENTUALLY, THE ENGINE COMPLETELY STALLS. THE SECOND FAILURE OCCURRED TODAY, AUG. 17, '07 AT APPROXIMATELY 8PM ON I-96 IN WIXOM, MI. I WAS ENTERING THE FREEWAY WITH HEAVY TRAFFIC. WHEN SHIFTING TO FIFTH GEAR AT 70 MPH, THE ENGINE LOST POWER. I RELEASED THE CLUTCH AND THE ENGINE STALLED. I MOVED TO THE SHOULDER, RESTARTED THE ENGINE, AND MANAGED TO MOVE THE VEHICLE ALONG THE SHOULDER FOR APPROXIMATELY 3/4 MILE ON ENGINE POWER BEFORE IT STALLED AGAIN. I THEN WALKED 2.5 MILES TO THE NEXT EXIT. WHILE IN THE PARKING LOT OF A RETAIL STORE, I MANAGED TO REMOVE THE "AUTO FUEL VALVE" WITH TOOLS PURCHASED FROM THE STORE. I CONNECTED THE FUEL TANK DIRECTLY TO THE CARBURETOR FUEL LINES, BUT I WAS UNABLE TO DRIVE THE VEHICLE AWAY. THE "AUTO FUEL VALVE" CONTROLS FUEL FLOW FROM THE TANK AND I BELIEVE IT ALSO ACTS AS A PUMP. THE "AUTO FUEL VALVE" IS AN ASSEMBLY THAT RETAILS FOR APPROXIMATELY $35. IT CONSISTS OF ALUMINUM CASTINGS, A SPRING AND A RUBBER DIAPHRAGM. CYLINDER FOUR CREATES VACUUM WHEN THE ENGINE CRANKS DURING STARTING AND PULLS THE DIAPHRAGM OPEN. THE VACUUM IS APPLIED TO THE DIAPHRAGM THROUGH A SMALL TUBE CONNECTED TO THE CARBURETOR FOR CYLINDER FOUR. WHEN THE DIAPHRAGM IS PULLED OPEN, GRAVITY CAUSES FUEL FROM THE FUEL TANK TO FLOW THROUGH THE ASSEMBLY AND ON TO THE CARBURETORS. DUE TO THE PULSATING OF THE DIAPHRAGM FROM THE MOVEMENT OF PISTON FOUR, THE DIAPHRAGM ALSO ACTS AS A FUEL PUMP. A SPRING NORMALLY PUSHES THE DIAPHRAGM CLOSED TO BLOCK FUEL FLOW TO THE ENGINE WHEN NO VACUUM IS APPLIED THE FAILURE OF THE ENGINE OCCURS WHEN THE RUBBER DIAPHRAGM DEVELOPS A TEAR ON THE OUTER EDGE. ENGINE VACUUM IS NO LONGER ABLE TO PULL THE DIAPHRAGM DUE TO THE TEAR AND FUEL STOPS FLOWING. THIS IS OBVIOUSLY A MAJOR SAFETY ISSUE DUE TO THE NATURE OF THE FAILURE. PHOTOS AND THE FAILURE PARTS ARE AVAILABLE. *JB