Cummins N14 – Engine Speed (RPM) With a Verified Tachometer

Use digital optical tachometer, Part No. 3377462, to check and verify engine speed.

Fuel Pressure
Measure the fuel pressure. Install the pressure gauge, Part No. ST-435-6, or the pressure gauge in the fuel
measuring device, Part No. 3376375, to the Compucheckா fitting on the fuel shutoff valve.
NOTE: Pressure gauge, Part No. ST-435-6, is included with snap rail pressure gauge, Part No. 3375932.

Fuel Drain Line Restriction
Use pressure gauge, Part No. ST-1273, to measure fuel drain line restriction.
NOTE: Do not measure fuel drain line restriction with the fuel measuring device installed. This will not measure the
drain line restriction of the vehicle’s return plumbing.

Hold the gauge at the same level as the connection.
NOTE: The gauge will not measure the correct pressure if the gauge is not held at the same level as the connection.

NOTE: All air compressors manufactured by Cummins Engine Company, Inc. must be operating during the engine
run-in. During the performance check, all air compressors must be in the unload or non-operating mode.
Connect a source of compressed air capable of producing 665 kPa [95 psi] to the air compressor unloader (1).
This air line must contain a valve between the source and the unloader.
NOTE: The compressed air load in the accompanying illustration must be attached to the air compressor outlet (2).

Use an air tank (2). Install an air regulator (3) capable of maintaining 345 to 517 kPa [50 to 75 psi] air pressure at
both minimum and maximum engine RPM.
Install a steel tube or high temperature hose (1).
Hose Temperature (Minimum): 235°C [500°F].
Connect the tube or hose (1) to the air compressor outlet.

NOTE: Inspect the voltage rating on the starting motor before installing the electrical wiring.
Install the electrical wiring to the starting motor and batteries, if used.
NOTE: If another method of starting the engine is used, follow the manufacturer’s instructions to make the necessary connections.