Diesel engines are known for their fuel efficiency, reliability, power, performance, and lower carbon emissions compared to gasoline engines. Diesel engines are commonly used in heavy-duty trucks and heavy construction equipment. However, maintaining diesel fuel injection systems (and most parts of your diesel engine truck as well) is essential to keep the engines running safely and effectively. In this post, we will share some tips for monitoring and maintaining diesel fuel injection systems.

Depressurize the fuel injection system before maintenance

Diesel fuel is under high pressure when operating, making it crucial to let the engine cool completely and depressurize the fuel injection system before performing any maintenance. Here is how to depressurize your fuel injection system:

  1. Shut off the engine and allow it to cool completely.
  2. Slightly loosen the fuel filter cap to let out the hiss when loosened.
  3. Consult your owner's manual to determine where your fuel lines are and turn a flare wrench counterclockwise to loosen (but not remove) the fittings.
  4. Wait several minutes for pressure to release and clean up any spills while waiting.
  5. Remove the fuel lines completely if replacing the filters. If not, leave them loosened until maintenance is completed.
  6. Signs of clogged or dirty fuel injectors

Diesel fuel is more viscous than gasoline and will hold dirt and debris in suspension more easily. If an engine's fuel injectors are clogged or dirty, the diesel fuel may dribble out instead of spraying a strong, fine mist, causing the engine to skip or stop entirely. The signs that you may have a clogged or dirty fuel injector are rough idling, hard starting, throttle hesitation, decreased fuel mileage, poor engine/machine performance, black smoke from the exhaust manifold, and pinging sounds (pre-ignition).

Tips for keeping fuel injection systems clean include changing oil regularly, replacing filters, and using high-quality additives that protect and clean the parts. However, it is important to consult the manual or manufacturer for recommended additives for your machine.

Signs of water in the fuel injection system

Water in a fuel system can cause the engine to miss or stop entirely. Today's fuel filters will automatically clog when exposed to water and stop fuel flow immediately. Any water that enters the tank upon fueling or forms via condensation will likely settle to the bottom of the tank and should be drained off each day in accordance with your machine's manual.

The signs that you may have water in your fuel injection system are pressure indicators showing varying degrees of pressure, engine missing or stopping entirely, fuel that appears dark and gummy (due to water mixing in with diesel fuel and causing microbe formation), sluggish performance, and erratic idling.