Generator Smoking

Is your diesel generator smoking (White, Black or Blue) whilst running? Then there are issues that you need to address.

It is perfectly normal for smoke to be produced during the first few seconds following start-up as diesel fuel in the cylinders is burned off. But this should clear very quickly into a translucent emission (see second video below).

You may also see some additional smoke when a heavy load is dropped onto the generator. This is because the generator has to adjust its fuel consumption to provide the additional power required to support the new load. Then after a few seconds, the exhaust smoke again becomes translucent, virtually invisible.

In normal use a generator should not produce continuous visible smoke from the exhaust silencer.

The colour of the generator smoke will usually help you to identify the cause of the problem. For example:1000kVA-Diesel-Generator-no-white-smoke

  • BLACK SMOKE– poor diesel combustion caused by an air/fuel ratio imbalance
  • BLUE SMOKE – oil entering the combustion chamber and burning 
  • WHITE SMOKE – fuel isn’t burning correctly and is passing through the diesel engine and exhaust unburnt

How to fix generator smoking issues:

  • BLACK SMOKE– Adjust the fuel lines and fuel input. Replace the fuel filters AND air filters. Check the quality of the fuel, because dirty and contaminated fuel is often the main thing to fix before following our other suggestions. Next, check the injectors and replace if necessary. Look for signs of ageing and contamination.
  • BLUE SMOKE – Replace the head gasket and any gasket/seal around the fuel filters and oil filters as soon as possible. Failure to replace will cause major generator failure and result in the costly replacement of parts.
  • WHITE SMOKE – Check the fuel supply and adjust to allow less fuel into the diesel engine. Also, check for water leaks that may have found their way into the fuel tank or engine block. Tighten jubilee clips around hoses. Check hoses.


Click the video below to see a generator WHITE smoking:

Click the video below to see what NORMAL generator smoke should look like on start up:



Regularly serviced & maintained generators by PowerContinuity never smoke!
Call 0854 055 8455 for any further help and advice


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