Cummins Diesel Engines : Operating Instructions

General Information  

Proper care of your engine will result in longer life, better performance, and more economical operation.  

  • Follow the daily maintenance checks listed in Maintenance Guidelines
  • Check the oil pressure indicators, temperature indicators, warning lights, and other gauges daily to make sure they are operational.


Do not operate a diesel engine where there are or can be combustible vapors.  These vapors can be drawn through the air intake system and cause engine acceleration and over-speeding(diesel engine runaway), which can result in a fire, an explosion and/or extensive property damage. Numerous safety devices are available, such as air intake shut-off devices, to minimize the risk of over-speeding where an engine, due to its application, might operate in a combustible environment, such as due to a fuel spill or gas leak. The equipment owner and operator are responsible for safe operation in a hostile environment. 

Starting Procedure

All pumps – above 16°C [60°F].  Foot off throttle. If engine does not start within five seconds of cranking, follow cold start procedures below.  

All pumps – below 16°C [60°F].  Fully depress the throttle after engaging the starter. Full throttle on the VE pump makes sure there is sufficient start fuel delivery and helps keep the engine operating once started. The inline pumps with RQV and RQV-K governors require full throttle to position and hold the rack in the start fuel position. The throttle must be depressed after engaging the starter to allow the shutoff lever to move to the run position before moving the throttle.


To prevent damage to the starter, do not engage the starting motor more than 30 seconds. Wait 2 minutes between each attempt to start (electrical starting motors only).  

  • If the engine does not start after three attempts, check the fuel supply system. Absence of blue or white exhaust smoke during cranking indicates no fuel is being delivered.
  • Move the throttle position to idle as soon as the engine starts.
  • Engine oil pressure must be indicated on the gauge within 15 seconds after starting.
  • When starting a cold engine, increase the engine speed (RPM) slowly to make sure adequate lubrication is available to the bearings.


Do not idle the engine for excessively long periods. Long periods of idling (more than 10 minutes) can damage an engine because combustion chamber temperatures drop so low the fuel will not burn completely. This will cause carbon to clog the injector spray holes and piston rings, and can cause the valves to stick. If the engine coolant temperature becomes too low (60°C [140°F]), raw fuel will wash the lubricating oil off the cylinder walls and dilute the crankcase oil; therefore, all moving parts of the engine will not receive the correct amount of lubrication.

Idle the engine 3 to 5 minutes before operating with a load.


When using jumper cables to start the engine, make sure to connect the cables in parallel: positive (+) to positive (+) and negative (-) to negative (-). When using an external electrical source to start the engine, turn the disconnect switch to the “OFF” position. Remove the key before attaching the jumper cables to prevent unintentional starter engagement.

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