The rail pressure supplied by the fuel pump is dependent
on the engine speed. It can also be varied by the operator
by changing the position of the throttle.
The main functions of the fuel pump are to provide:
• Transfer of fuel from tank to engine
• Rail pressure to injectors
• Idle speed governing
• Maximum speed governing
• Operator control of power output below governed
speed (throttle)
• Control of exhaust smoke during acceleration (AFC-
Air Fuel Control)
• Shutdown of the engine
The flow area of the injectors is determined by the cal-
ibration of a complete set of injectors. The injector cali-
bration is determined primarily by the parts which make
up the injector. The Control Parts List (CPL) manual lists
the injector assembly and flow plus the combination of
other basic engine parts which are necessary to produce
a given level of engine performance.
The calibration flow rate of the injectors is determined by
the size of an adjustable orifice. Each injector in the
engine is calibrated to the same flow rate. The flow rate
adjustment must be done by a Cummins Authorized Fuel
Systems Location.
Section 5 - Fuel System Fuel System General Information
N14 Page 5-5
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