Best Practices

Tier III Engine Maintenance

Keeping your fuel system clean is critical to proper engine operation

The Tier III engine's diesel fuel injection systems requires an extremely high fuel pressure—often over 25,000 psi—to function correctly. Without the high pressure, the burn pattern is not sufficient to produce the low contaminant emissions required by federal regulations.

Fuel systems tolerances between components have been reduced to assure that regulatory requirements are met. It is important to control contaminants in the fuel system to assure that all parts are working properly. Additional damage to the engine can occur due to contaminated fuel, and this type of damage may not be covered by warranty or may void the engine's warranty.

Below are some helpful tips to keep contaminants from entering your fuel system.

  • Do not pre-fill the fuel filters. Fuel used for this purpose is usually
    contaminated and has not been filtered. It can damage critical fuel system parts. For Tier III engines, the filter must be kept clean and installed without pre-filling. Refer to your equipment manual for proper procedures, or use an electric fuel pump to fill the filter with filtered fuel.
  • All maintenance procedures should be completed by a trained, qualified service technician. Miller-Bradford & Risberg's technicians have been certified to service Tier III engines.
  • The work environment must be sterile and free of airborne contaminants. A modern injector's internal drillings are quite small and extremely susceptible to clogging. Any type of plugging in an injector can cause dribbling and, possibly, engine damage.
  • The high pressure in the Tier III engine's fuel injection systems operation can transform small particles of dirt, dust and rust into extremely abrasive contaminants that can severely damage components. Many modern injectors cannot be serviced but must be completely replaced if damaged.
  • Do not use compressed air to clean dirt from fuel system fittings. Use an electrical contact cleaner or a spray parts cleaner. Keep exposed fuel system parts clean. Diesel fuel attracts airborne particles. The fitting frequently will have a residue where the work is being completed, even when there's a small amount of fuel at the fitting.
  • Many engines require secondary fuel filtration at a level of 3 microns. A filter's micron rating indicates the size of the smallest particles that the filter will capture. Micron is an abbreviation for micrometer, one millionth of a meter. A human hair measures .003 mm/3/1000” in diameter. A micron measures 0.00004 mm/4/100,000”.
  • Frequently clean all tools used for fuel system troubleshooting and repair. They may be overlooked as a possible source for contamination. Residual oil or fuel on the tools will attract airborne contaminants. Always clean tools before using them.
  • Cap and plug fuel lines, fittings, and ports any time the fuel system is opened to help avoid contamination. Though the repair may only take a short time, airborne contaminants can drift in from an adjacent bay, through an inadvertent bump against the engine housing or off someone's dirty clothing.

Additional Tips

Low Sulfur Fuel Requirements—It is always important to use the correct low sulfur fuel with your Tier III engine. Refer to your operator's manuals to identify the sulfur requirements for all of your equipment.

Engine Maintenance—The fuel system components for the Tier III engines are much more expensive than those for the older engines, particularly the injection pumps. By following all recommended procedures for engine maintenance, the need for component replacement due to improper usage is unlikely, however.

Warranty Coverage Requirements—When procedures detailed in the operator's manual have not been followed, and the manufacturer refuses to cover repairs under warranties, the equipment owner is liable for these repair expenses. Warranties will not cover damage from water, contamination, or use of incorrect fuel for injection pumps.