Do fuel systems really need to be cleaned?

You might be forgiven for thinking fuel systems no longer need any attention, after all, with modern refining technology fuels have never been so clean. The fuel system, however, is not a sealed system, nor is the engine itself. So, no matter how high quality the fuel is, deposits, gum and oxidisation build up over time. Oddly enough, modern fuels tend to absorb more moisture than older, conventional fuels.

As fuel deteriorates, residues and oxidation take their toll on the fuel system, affecting performance and causing damage to fuel system components. In figure 1 and figure 2 you can see the degree to which fuel degrades. The test shows how petroleum spirit is affected, even promoting oxidation.


Figure 1 – Beginning of fuel stabiliser test

Figure 2 – End of fuel stabiliser test

Choked fuel system components

Varnish and gum build up in the fuel lines, fuel pump, fuel injectors and carbon accumulates on the inlet valves. The gradual deterioration of parts delivering the fuel-air mixture, means that the components no longer function as they were designed to. The easiest way of remedying the problem – without going to the expense and inconvenience of removing and cleaning fuel system components – is to use a tin of BIZOL Gasoline System Clean+ g80 or for diesels BIZOL Diesel System Clean+ d60.

Noise from the engine

General rattles, timing chain chatter and other noises from the engine can be caused by poor fuelling, due to rough running behaviour. Deposits also restrict the supply of fuel and negatively affect the injector spray pattern, just like a shower head when the jets are blocked by limescale. The fuel injectors get clogged by fine deposits limiting the flow of fuel.

Changes to the spray pattern affect fuel atomisation and injection duration, which, in turn, means that the engine management system has to increase injector duration to compensate. Poor fuel atomisation reduces combustion efficiency, increasing fuel consumption and reducing amount of power at your disposal. The longer the problem is left untreated, the greater the effect on the fuel system and engine.

One application of BIZOL Gasoline System Clean+ g80 already dissolves many of the accumulated deposits, but it is advised to use the treatment regularly to keep trouble at bay.

Figure 3 – before and after treatment

If left unchecked a build-up of deposits will, at first, cause a gradual loss of power. Many of the signs that a problem is developing are often not recognised or ignored. And that is the reason why cleaning away the deposits is essential, as prevention is better than cure.

Problems caused by a build-up of deposits include:

  • loss of performance
  • increased fuel consumption
  • increased emissions
  • poor starting and idling behaviour
  • emissions test failure
  • poor driveability
  • erratic idling
  • poor throttle response

BIZOL Fuel System Cleaners

BIZOL System Clean+ g80 and BIZOL System Clean+ d60 are compatible with all commercially-available fuels and provide the following benefits:

  • restore performance
  • remove deposits from the fuel system
  • remove combustion products from the engine
  • prepare the engine for the next oil change
  • can reduce abnormal engine noise
  • restore oil flow and extends engine life
  • restore the function of critical components, e.g.:
    fuel pump
    injectors
    inlet valves
    fuel lines
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