834990 Mercruiser PULLEY

Illustration 1 g01428177
Diagram of the basic fuel system for C6.4 (typical example) (1) Electronic unit injector (EUI) (2) Solenoid for the fuel injection pump (3) Secondary speed/timing sensor (4) Electronic control module (ECM) (5) Fuel injection pump (6) Primary speed/timing sensor (7) Intake manifold pressure sensor (8) Fuel manifold pressure sensor (9) Engine oil pressure sensor (10) Water temperature sensor (11) Intake manifold temperature sensor (12) Coolant temperature sensor (13) Diagnostic connector
Illustration 2 g01428191
Diagram of the basic fuel system for C4.2 (typical example) (1) Electronic unit injector (EUI) (2) Solenoid for the fuel injection pump (3) Secondary speed/timing sensor (4) Electronic control module (ECM) (5) Fuel injection pump (6) Primary speed/timing sensor (7) Intake manifold pressure sensor (8) Fuel manifold pressure sensor (9) Engine oil pressure sensor (10) Water temperature sensor (11) Intake manifold temperature sensor (12) Coolant temperature sensor (13) Diagnostic connectorLow Pressure Fuel System
Illustration 3 g01620064
(14) Third fuel filter (15) Secondary fuel filter (16) Primary fuel filter (17) Fuel priming pump (18) Fuel tank (19) Fuel transfer pump (4) ECMThe low-pressure fuel circuit supplies filtered fuel to the fuel injection pump at a constant rate. The low-pressure fuel circuit cools the ECM. The low-pressure fuel circuit provides fuel at 500 kPa (72.5 psi).High Pressure Fuel System
Illustration 4 g01620068
High-pressure fuel system (typical example) (1) Electronic unit injector (5) Fuel injection pump (8) Fuel pressure sensor (19) Fuel transfer pump (21) High-pressure fuel manifold (22) Fuel pump gear (23) Solenoid for the fuel injection pump (24) Fuel pressure relief valveThe fuel injection pump (5) feeds fuel to the high-pressure fuel manifold (21) . The fuel is at a pressure of 70 MPa to 130 MPa (10153 psi to 18855 psi). A pressure sensor (8) in the high-pressure fuel manifold (21) monitors the fuel pressure in the high-pressure fuel manifold (21) . The ECM controls a solenoid (23) in the fuel injection pump (5) in order to maintain the actual pressure in the high-pressure fuel manifold (21) at the desired level. The high-pressure fuel is continuously available at each injector. The ECM determines the correct time for activation of the correct electronic unit injector (1) which allows fuel to be injected into the cylinder. The leakoff fuel from each injector passes into a drilling which runs along the inside of the cylinder head. A line is connected to the rear of the cylinder head in order to return the leakoff fuel to the pressure side of the fuel transfer pump.Components of the Fuel Injection System
The fuel injection system has the following mechanical components:
Primary filter/water separator
Fuel priming pump
Secondary fuel filter
Fuel injection pump
Fuel injectors
Fuel manifold
Pressure relief valve
Fuel pressure sensor The following list contains examples of both service and repairs when you must prime the system:
A fuel filter is changed.
A fuel line is replaced.
The fuel injection pump is replaced.Primary Filter/Water Separator
The primary filter/water separator is located between the fuel tank and the priming pump.Fuel Priming Pump
Illustration 5 g01812193
Hand fuel priming pumpThe pump has a plunger (25) which is manually operated in order to prime the fuel system. Air is removed from the fuel system to the fuel return line to the tank. The fuel transfer pump is located in the fuel injection pump.Note: Machines that are equipped with optional fuel filtering equipment have the hand fuel priming pump located on the primary fuel filter base.Secondary Fuel Filter
Illustration 6 g01812195
The secondary fuel filter (15) is located after the priming pump. The filter is always before the fuel injection pump.Note: Certain machines are equipped with additional secondary fuel filters.Fuel Pump Assembly
The fuel pump assembly consists of a low-pressure transfer pump and a high-pressure fuel injection pump. The pump assembly is driven from a gear in the front timing case at half engine speed. The fuel injection pump has two pistons that are driven by a camshaft. There is a cam for each piston and each cam has three lobes. The fuel injection pump delivers a volume of fuel six times for each revolution. The stroke of the pistons is fixed. The injector will use only part of the fuel that is delivered by each stroke of the pistons in the pump. The solenoid for the fuel injection pump is controlled by the ECM in order to maintain the fuel manifold pressure at the correct level. The solenoid allows excess fuel to be diverted away from the fuel manifold and back to the tank. A feature of the fuel injection pump allows fuel to return to the tank continuously.Fuel injection Pump
Illustration 7 g01343647
The fuel injection pump generates high pressure for the fuel system.The fuel output of the fuel injection pump is controlled by the ECM in response to changes in fuel pressure.