21971 Mercury NUT, STOP SWITCH TO BOTTOM COWL

Cylinder And Valve LocationBore ... 137.2 mm (5.40 in.)Stroke ... 152.4 mm (6.00 in.)Number And Arrangement Of Cylinders ... 65° V-12Firing Order (Injection Sequence) ... 1,4,9,8,5,2,11,10,3,6,7,12Rotation of Crankshaft (when seen from flywheel end) ... counterclockwiseRotation of Fuel Pump Camshaft (when seen from pump drive end) ... counterclockwise Front end of engine is opposite to flywheel end. Left side and right side of engine are as seen from flywheel end. No. 1 cylinder is the front cylinder on the left side. No. 2 cylinder is the front cylinder on the right side.Fuel System
Fuel System Schematic
(1) Fuel inlet line for the injection pump housing. (2) Damper. (3) Adapter with orifice. (4) Injection pump housing. (5) Fuel return line. (6) Junction block. (7) Fuel tank. (8) Fuel supply line. (9) Primary fuel filter. (10) Fuel transfer pump. (11) Pressure relief valve. (12) Priming bypass valve. (13) Fuel priming pump. (14) Main fuel filters. (15) Fuel pressure gauge.This engine has a pressure type fuel system. There is one injection pump and injection nozzle for each cylinder. The injection pumps are in pump housing (4) on top front of the engine. The injection nozzles are in the precombustion chambers or adapters (for engines with direct injection) under the valve covers.Fuel transfer pump (10) pulls fuel from fuel tanks (7) through primary filter (9) and sends it through priming pump (13), main filters (14) and to the manifold of the injection pump housing. The fuel in the manifold of the injection pump housing goes to the injection pumps. The injection pumps are in time with the engine and send fuel to the injection valves under high pressure.On the inlet fitting