24 Valve Cummins Turbo Diesel

Improvements and design changes that set it apart from the 12 Valve series
Page 5 - Fuel System (continued)

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FUEL SYSTEM

• Electronic Fuel System Control
• Engine control relies on two different Cummins-built electronic modules.
• The FPCM (Fig 22) is attached to the pump and is wired through a 9 pin connector to the ECM.
• The ECM (Fig 23) is mounted to the driver's side of the engine behind the fuel filter.

• The ECM and FCPM modules are OBD II compliant.
• The ECM communicates with the FCPM and the Ram PCM over a two wire CCD data bus.
• The ECM has taken control of some fuel system functions that were previously handled by the PCM.
• The ECM uses information from sensor and data inputs for fuel control, including an electronic governor.

• ECM Inputs:
• Accelerator Pedal Position Sensor (APPS) (Fig 25 above) - similar to the TPS
• battery voltage
• Camshaft Position Sensor (CMP)
• Crankshaft Position Sensor (CKP)
• CCD Bus (+ and -)
• Data Link Connector
• Engine Coolant Temperature sensor (ECT)
• Intake Air Temperature sensor (IAT)
• Manifold Air Pressure sensor (MAP)
• Oil Pressure sensor
• PCM
• Water In Fuel sensor (WIF)
• power ground
• sensor return (ground)
• Signal ground
• DO NOT ADJUST the idle stop screws which are preset at the factory.
• Bell Crank Assembly
• The bell crank assembly (Fig 26) serves as a junction point for the accelerator pedal linkage, the speed control servo cable, the transmission throttle valve cable linkage, and the APPS.

• Only the Transmission cable linkage is adjustable.
• The APPS position is calibrated to it's mounting bracket. If the APPS is faulty the entire bell crank assembly must be replaced as a unit.
• A fuel system relay has been added to the PDC (Fig 27) to supply power to the FPCM.

• Electric Transfer Pump
• An electric fuel transfer pump (Fig 28) is used instead of a mechanical lift pump. The pump is located on the left side of the engine.

• Controlled by the ECM, the transfer pump uses pulse width modulation to provide two duty cycles: full speed when the engine is running and half speed at crank to prevent overpressure that could keep the injection pump from operating.
• The pump is self priming and needs no mechanical priming push-button
• Fuel Filter
• The fuel filter contains a disposable cartridge-type element and includes an electric fuel heater.
• The filter is similar to the 12 valve engine filter except for two ports (Fig 29) that can be used for fuel pressure testing.

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