How To Properly Maintain Fuel Systems

Updated Jan 2, 2014

In a world full of Tier 4 engines with high-pressure common-rail systems, maintaining fuel systems in your equipment is imperative for performance and engine health.

Even the slightest contaminants can affect a Tier 4 engine causing a variety of problems.

Case Construction Equipment has put together a few tips on how to treat and maintain a fuel system.

Consider the Source
Fuel quality in North America is generally pretty good.

Having said that: source your fuel from a reputable source with a track record for clean and fresh diesel.

Diesel fuel begins to degrade as it ages. This degradation leads to the formation of a variety of “organic” materials within the fuel that clogs filters and can impede performance of the engine.

As filters clog and that material works its way into the injectors, the chances of abrasion wear increases.

Putting old diesel into a high-performance diesel engine starts you off on the wrong foot immediately.

How to Store
It is recommended that portable tanks of diesel be stored inside to prevent exposure to temperature fluctuations that can cause condensation.

That condensation then provides a direct source of water into the diesel fuel. Some even suggest filling equipment tanks at the end of each shift to minimize the physical space on the inside of the tank where condensation can occur.

It is also recommended to outfit bulk storage tanks with breathers and dryers designed to keep water and contaminants out of the diesel, as well as added filtration at the input and output as another line of defense. 

Eliminating water is important as it presents numerous challenges: it encourages further microbial growth, and water that bypasses the water separator can cause internal damage to the injectors and corrosion throughout the system.

Water in diesel also reduces the heat of combustion, which can rob the engine of power. Water in diesel can also freeze and accelerate the gelling process that occurs when diesel drops below a certain temperature in cold weather climates.

Most equipment now has a warning light that lets you know that your water separator is full, but it is also suggested to make it a point to drain the water from the water separator daily to ensure optimal performance.

Effects of Biodiesel
Cat Tier 4Biodiesel tends to degrade faster than petroleum-based diesels and have a greater affinity to water, clogging filters at a faster rate and requiring a greater level of maintenance/vigilance in monitoring performance.

A note on storage tanks: keep an eye out for damage, rust and possible holes on the tank. These can provide opportunities for materials to enter the tank and contaminate the fuel.

Also – quite basic: when filling your machine’s tank, make sure the area surrounding the fueling point is free and clear of any dirt or debris that can enter the tank.

Jobsites are not “clean”, by nature, but every attempt should be made to maintain the quality of the diesel fuel that enters the machine. Always remember to replace the fuel cap and tighten it.

The Basics
First, always make sure it is diesel that is going into the tank.

With the introduction of diesel exhaust fluid (DEF) in Tier 4 selective catalytic reduction (SCR) technologies, we have heard anecdotes related to workers accidentally putting DEF into the fuel tank and causing thousands of dollars worth of damage to the engine and fuel system.

Secondly, it is equally important not to mistakenly pump diesel fluid into the DEF tank as this can cause serious damage to various system components such as the DEF injector and SCR Catalyst. 

It is vitality important DEF quality is up to the strict purity requirements as listed in the ISO 22241-1 specification of 32.5 percent water to 67.5 percent urea. Always think twice before fueling and/or filling DEF and diesel. The DEF and diesel fill points are clearly marked.    

Safety First
Appropriate safety measures must be taken. Proper safety glasses and other personal protective equipment should always be worn.

The pressures at which HPCR systems operate at are extremely high (some over 30,000 psi). Exposure to pressurized liquids can cause harm to exposed skin—always depressurize the system prior to maintenance as instructed in the machine’s owner’s manual.

Fuel collected during the maintenance process should be properly captured and stored, and disposed of through appropriate channels. 

Working Environment Matters
Perform repairs indoors when possible. If this is not possible and you’re working on a large, outdoor site, erect windbreaks as needed to protect the work area from airborne contaminants. Use clean and dedicated tools to plug fuel lines and other gateways to the fuel system to minimize the risk of contamination.

Also use clean tools throughout the process so as not to introduce other foreign dirt and oils to the components. If using compressed air, ensure your air supply is moisture free.

One common mistake that is made is filling the fuel filter with diesel prior to installation. All this does is introduces unfiltered diesel fuel into the system and provides greater access for contaminants to the injectors and other sensitive components.

Always install the fuel filter without adding diesel and prime the engine separately before starting.    

A few key fuel system maintenance suggestions:

  • Change fuel filters at or before intervals determined by the manufacturer
  • Use filter types and sizes approved for use by the manufacturer (it’s also best to have the same micron size filter as the fuel system requires installed on all fuel storage tanks to ensure a clean supply).
  • Drain water from the water separator daily, or immediately when the water separator warning light goes on.
  • Periodically check the fuel lines and other components for leaks. It is always safe to assume that, if diesel is leaking out, that air, dirt and other contaminants may be entering the system through the same leak. Finding the source of leaks and making that repair immediately is important. Leaks of all sizes pose a problem as it only takes a small contaminant a few microns in size to cause problems with injectors, etc.     
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