40001206 Mercruiser SCREW

Fuel System
The Sleeve Metering Fuel System (SMFS) is a pressure type fuel system. The name for the fuel system is from the method used to control the amount of fuel sent to the cylinders. This fuel system has a fuel injection pump for each cylinder of the engine. It also has a fuel transfer pump on the front of the fuel injection pump housing. The governor is on the rear of the fuel injection pump housing.The drive gear for the fuel transfer pump is on the front of the camshaft for the fuel injection pumps. The carrier for the governor weights is bolted to the rear of the camshaft for the fuel injection pumps. The fuel injection pump housing has a bearing at each end to support the camshaft. The camshaft for the sleeve metering fuel system is driven by the timing gears at the front of the engine.The fuel injection pumps, lifters and rollers, and the camshaft are all inside of the fuel injection pump housing. The fuel injection pump housing and the governor housing are full of fuel at transfer pump pressure (fuel system pressure).
Diesel fuel is the only lubrication for the moving parts in the fuel transfer pump, fuel injection pump housing and the governor. The fuel injection pump housing must be full of fuel before turning the camshaft.
This fuel system has governor weights, a thrust collar and two governor springs. Rotation of the shaft for governor control, compression of the governor springs, movement of connecting linkage in the governor and fuel injection pump housing controls the amount of fuel sent to the engine cylinders.In addition to the SMFS, later model engines may be equipped with the Heavy Sleeve Metering Fuel System (HSMFS), or a fuel system that contains features from the earlier (SMFS) and the (HSMFS). The SMFS, HSMFS, and the hybrid fuel systems all function similarly. The hybrid and HSMFS have bolted spill shields, a pressure relief valve returns excess fuel to the tank, square bypass opening port plungers, and overpressure vent to inlet on the fuel inlet flange. Additionally the HSMFS has thicker walled sleeves to reduce high pressure fuel bleed off, side control levers and high rate smoke limiter without preload. The HSMFS is used with Caterpillar DIFN (Direct Injection Fuel Nozzles). The hybrid fuel system uses 7000 series nozzles.Sleeve Metering Fuel System (SMFS)
Sleeve Metering Fuel System (SMFS) Fuel Flow Schematic
(1) Fuel priming pump (closed position). (2) Fuel priming pump (open position). (3) Return line for constant purge valve. (4) Constant purge valve. (5) Manual purge valve. (6) Fuel injection nozzle. (7) Fuel tank. (8) Check valve. (9) Check valve. (10) Check valve. (11) Fuel inlet line. (12) Water separator. (13) Fuel filter. (14) Fuel line. (15) Fuel transfer pump. (16) Fuel bypass valve. (17) Camshaft. (18) Fuel injection pump housing.Fuel from fuel tank (7) is pulled by fuel transfer pump (15) through water separator (12) (if so equipped) and fuel filter (13). From fuel filter (13) the fuel