3856345 Volvo.Penta Propeller

Illustration 1 g01114686
(1) Fuel supply line
(2) Electronic unit injectors
(3) Fuel gallery
(4) Fuel temperature sensor
(5) Fuel return line
(6) Fuel filter base
(7) Fuel filter
(8) Fuel priming pump
(9) Fuel transfer pump
(10) Primary filter/water separator
(11) Fuel tank The fuel supply circuit is a conventional design for electronic unit injector diesel engines. Fuel transfer pump (9) of the circuit is a gear type pump with positive displacement. The fuel transfer pump is located in the front of the engine at the lower left corner. The fuel transfer pump is mounted to the front timing gear cover. The fuel transfer pump is driven by the front gear train.The fuel transfer pump draws fuel from fuel tank (11). The fuel passes through primary filter/water separator (10). The fuel passes into the fuel transfer pump and the fuel is then pressurized. The fuel transfer pump incorporates a check valve in order to permit a fuel flow around the gears for hand priming. The fuel transfer pump also incorporates a relief valve in order to protect the system from extreme pressure. The excess fuel flow that is provided by the fuel transfer pump is used in order to cool the electronic unit injectors. The excess fuel flow also purges the air from the fuel system.The fuel from the fuel transfer pump flows through 2 micron fuel filter (7) at fuel filter base (6). Fuel temperature sensor (4) is mounted in the fuel filter base. The Engine Control Module (ECM) uses the sensor to monitor the temperature of the fuel that is entering the engine. The information is used by the ECM to calculate a fuel correction factor during engine operation. Fuel priming pump (8) is positioned on the fuel filter base in order to prime the system when air has been introduced into the fuel system. For more information on priming the fuel system, refer to Testing and Adjusting, "Fuel System - Prime".The fuel leaves the fuel filter base and flows through fuel supply line (1) to the cylinder head. The fuel enters the cylinder head at the front of the engine. Fuel is delivered to electronic unit injectors (2) through fuel manifold (3) that is drilled into the cylinder head during the manufacturing process.Excess fuel exits the cylinder head at the rear. The fuel returns to the fuel filter base through fuel return line (5) to the pressure regulating valve that is incorporated into the fuel filter base. The pressure regulating valve maintains a sufficient amount of back pressure in the system in order to fill the electronic unit injectors. After the fuel passes through the pressure regulating valve, the fuel returns to the fuel tank. The fuel flows continuously from the fuel supply through the electronic unit injectors in the head and back to the tank.Fuel Recirculation (if Equipped)
A system for fuel recirculation may be installed on this engine in order to supply warm fuel to the unit injectors during cold engine operation. A thermostatic valve is in the open position when the fuel is cold. This allows the warm fuel to re-enter the fuel transfer pump instead of going back to the fuel tank. When the fuel reaches 80 °C (176 °F) the thermostatic valve will close directing the warm fuel to the fuel tank. Fuel Heaters
Fuel heaters prevent the plugging of the fuel filters in cold weather. This plugging is called waxing. The engine will not dissipate enough heat in order to prevent waxing. Heaters that are not thermostatically controlled can heat the fuel in excess of 65 °C (149 °F). High fuel temperatures will reduce the engine performance, the transfer pump check valve, and the system reliability.Note: Never use fuel heaters that do not have some type of temperature regulator that is incorporated into the system.Fuel System Electronic Control Circuit
The injection pump, the fuel lines, and the nozzles that are used in the traditional Caterpillar diesel engines have been replaced with a mechanically actuated electronically controlled unit injector in each cylinder. A solenoid on each injector controls the amount of fuel that is delivered by the injector. The ECM sends a signal to each injector solenoid in order to provide complete control of the engine.Electronic Controls
The electronic control system consists of two main components:
ECM
Personality moduleThe ECM is the computer. The personality module is the software for the computer. The personality module contains the operating maps. The operating maps define the following characteristics of the engine:
Horsepower
Torque curves
Engine speed
Other characteristicsThe ECM determines a desired rpm that is based on the following criteria:
Accelerator pedal position
Diagnostic codes
Status of the switch for the Power Take-Off (PTO)
Vehicle speedThe vehicle must be in a cruise mode or a PTO mode in order to use the last two criteria.The ECM maintains the desired engine speed by sensing the actual engine rpm. The ECM calculates the amount of fuel that needs to be injected in order to achieve the desired rpm.Fuel Injection
This engine uses an injection system control that allows variable control of the injector's spray pattern during the duration of fuel injection into the cylinder. A pilot injection takes place in order to start fuel combustion in the cylinder. When the pilot injection has been completed, the fuel injection delivery is then controlled by the ECM in order to optimize the combustion efficiency for the current operating conditions. This requires a new camshaft with a modified injector lobe.The ECM controls the amount of the fuel that is injected by varying the signals to the electronic unit injectors. The electronic unit injectors will inject fuel only if the electronic unit injector solenoid is energized. The ECM sends 120 VDC to the solenoid in order to energize the solenoid. By controlling the timing of the 120 volt signal, the ECM can control injection timing. By controlling the duration of the 120 volt signal, the ECM can control the injected fuel amount.The ECM sets certain limits on the amount of fuel that can be injected. The FRC fuel position is a limit that is based on boost pressure in order to control the air/fuel