Fuel system faults

Continuing the theme of faults in forest machines, we decided to expand on the fuel system due to its complex nature.

What may need repair/replacement?

  • tank
  • fuel pump (supply)
  • filters
  • wires
  • injection pump (or high pressure pump in CR fuel systems)
  • injectors

Let’s start with the tank. The walls of this component may collapse or expand, impeding the flow of fuel. In addition, when impurities appear in the tank, the fuel pump is at risk of failure.

When it comes to filters, the most common problem is clogging, which is usually caused by too infrequent replacement, water getting into the tank of the vehicle or the use of poor quality fuel. One of the symptoms may be a problem with starting the engine, jerking when moving off, idling or increased fuel consumption.

A fault in the fuel lines can have very serious consequences, but often there are no warning signs in the initial phase. So how do you avoid a serious bug? During daily service, but also during each visit to the workshop, we should have the wires checked, in particular those sections that are exposed and clearly visible from the engine and fuel tank. Wires with abrasions, crushing or very dirty should be replaced. Unfortunately, when we notice leaks or smell a strong fuel smell, the losses can be huge due to the risk of fire in the engine compartment.

Another common component that fails is the injection pump. It occurs due to:

  • impurities in the tank that are sucked in by the pump
  • damage to fuel filters
  • operating the machine with a small amount of fuel in the tank
  • faulty/loose electrical wires
  • fuel pump relay failure or fuel pump fuse blown
  • mechanical wear at high mileage

However, the symptom suggesting the upcoming problems may be:

  • very difficult engine start
  • problem starting the engine
  • engine stalling after starting
  • jerking when accelerating

The last component is the injectors. They fail most often due to poor quality fuel, but also due to flaking of the metal elements of the injection pump or too rare replacement of filters. What signs should we be concerned about? First of all, the problem with starting the engine, excessive smoke, increased fuel consumption, uneven engine operation, power drops and the smell of fuel released from the engine oil.

As you can see, the symptoms of all the faults mentioned above may be similar. So where to start?

In the first place, it is worth replacing the filters, which often turn out to be the cause of problems. However, if this treatment does not bring results, deeper diagnostics should be started. It is best to leave the equipment in the hands of professionals who have experience and repair forest machines on a daily basis.