CABLE AS 1717426 - Caterpillar

Illustration 1 g01017623
(1) Fuel supply line (2) Electronic unit injectors (3) Fuel gallery (4) Pressure regulating valve (5) Fuel filter (6) Fuel priming pump (7) Distribution block (8) Fuel temperature sensor (9) Fuel transfer pump (10) Relief valve (11) Check valve (12) Fuel tankThe 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 fixed clearance. The fuel transfer pump delivers fuel from fuel tank (12) to electronic unit injectors (2). Fuel is pulled from the fuel tank by the fuel transfer pump. The fuel transfer pump incorporates a check valve (11) in order to permit a fuel flow around the gears for hand priming. The fuel transfer pump also incorporates a relief valve (10) in order to protect the system from extreme pressure. The excess fuel flow that is provided by the fuel transfer pump cools the electronic unit injectors. The excess fuel flow also purges the air from the electronic unit injectors.The fuel in the fuel transfer pump flows through the cored passages in distribution block (7) and through a 2 micron fuel filter (5). Fuel priming pump (6) is positioned on the fuel filter base in order to prime the system when air has entered the fuel system. For more information on priming the fuel system, refer to Testing and Adjusting, "Fuel System - Prime".The fuel enters the fuel manifold at the rear of the cylinder head. The fuel flows continuously from the fuel supply through the electronic unit injectors. This fuel then returns to the tank by the return line for the fuel manifold. Fuel is displaced by the plunger when the fuel is not being injected into the cylinder. This fuel returns to the tank by the fuel return manifold. For more information, refer to the topic on electronic unit injectors in Systems Operation, "Fuel System".Pressure regulating valve (4) is located in the distribution block. The pressure regulating valve maintains a sufficient amount of back pressure in the system in order to fill the electronic unit injectors.Fuel transfer pump (9) is located in the front of the engine at the lower left corner. The fuel transfer pump is mounted to either the front timing gear cover or a plate. The fuel transfer pump is driven by the gear train.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: Fuel heaters without some type of temperature regulator must never be used.Two types of fuel heaters can be used: thermostatically controlled and self-adjusting.Fuel System Electronic Control Circuit
Illustration 2 g00597197
Logic for engine speed control (A) Logic for CRUISE/PTO (B) Control for CRUISE/PTO (C) Engine control logic (D) Coolant temperature sensor