Centinel System – Repair Manual – 005-999   Fuel System – Overview

General Information

WARNING  Depending on the circumstance, diesel fuel is flammable. When inspecting or performing service or repairs on the fuel system, to reduce the possibility of fire and resulting severe personal injury, death or property damage, never smoke or allow sparks or flames (such as pilot lights, electrical switches, or welding equipment) in the work area.  CAUTION  Tampering with the fuel system can void the engine warranty and lower the performance of the engine. NOTE: Warranty repairs are not to be made to the Signature, ISX, or QSX fuel system unless the work is performed in a shop that meets all requirements established by Cummins Inc. to accurately calibrate, test, and repair the fuel systems on Cummins® engines. The performance of the engine is defined by the control parts list and the fuel system code. The fuel system calibration must be within published specifications. Fuel system calibration is certified by several emissions agencies.		SMALL | MEDIUM | LARGE
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NOTE: There is no mechanical throttle on the Signature, ISX, or QSX15 fuel system. The Signature, ISX, and QSX15 fuel system is an integrated, multi-part system. It is comprised of the following: Supply pump Regulators Filters Timing and fueling actuators Camshaft-driven injectors 1 through 6 ECM, sensors (fuel system control).		SMALL | MEDIUM | LARGE
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The fuel system is split into two banks: Front bank (cylinders 1-2-3) Rear bank (cylinders 4-5-6).		SMALL | MEDIUM | LARGE
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Automotive with CM870

System Operation

• Fuel is drawn from the tank through a fuel filter by a gear pump (supply pump)
• The supply pump pressure is regulated at 1689 to 2206 kPa [245 to 320 psi] at 2100 rpm
• Fuel passes through a pressure side filter (36 microns)
• Fuel then passes through a rapid restart-style fuel shutoff valve
• Fuel enters a passage feeding the front and rear banks, which connects directly to the fuel actuators
• Within a given bank, the fuel and timing actuators are commanded by the ECM to open
• The opening of each actuator sends a pressure pulse to each injector within the bank
• The timing of these events is tied to engine position
• Due to the firing order (1-5-3-6-2-4) and cam position,
  only one injector within the bank receives fuel.

The Signature, ISX, and QSX fuel system assembly, integrated fuel system module, or fuel delivery housing is located on the intake side of the engine.

Fuel for the Engine

• Fuel passes through a rapid restart-style fuel shutoff valve
• Fuel enters a passage feeding the front and rear banks, which connects directly to the fuel actuators
• Within a given bank, the fuel and timing actuators are commanded by the ECM to open
• The opening of each actuator sends a pressure pulse to each injector within the bank
• The timing of these events is tied to engine position
• Due to the firing order (1-5-3-6-2-4) and cam position,
  only one injector within the bank receives fuel.

Automotive With CM871

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Aftertreatment Injector Fuel Flow.

System Operation

• Fuel is drawn from the tank through a fuel filter by a gear pump (supply pump)
• The supply pump pressure is regulated at 1689 to 2220 kPa [245 to 322 psi] at 2100 RPM
• Fuel passes through a pressure side filter (10 microns).
• Fuel goes to the engine and the aftertreatment system.

Fuel For the Engine

• Fuel passes through a rapid restart-style fuel shutoff valve
• Fuel enters a passage feeding the front and rear banks, connecting directly to the fuel actuator.
• Within a given bank, the fuel and timing actuators are commanded by the ECM to open
• The opening of each actuator sends a pressure pulse to each injector within the bank
• The timing of these events is tied to engine position
• Due to the firing order (1-5-3-6-2-4) and cam position,
  only one injector within the bank receives fuel.

Fuel For the Aftertreatment System

• Fuel flows down to the aftertreatment shutoff valve
• When the valve opens, the fuel passes the aftertreatment fuel pressure sensor
• Fuel then flows around the back of the engine to the aftertreatment fuel injector
• When the aftertreatment fuel injector opens, fuel is sprayed into the exhaust stream
• When the fuel is
  not flowing to the aftertreatment fuel injector, remaining fuel in the line between the first aftertreatment shutoff valve and aftertreatment fuel injector is sent through the second aftertreatment shutoff valve to drain.

Installation Recommendations