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White Smoke Indicates a Faulty Fuel System: Time for a Fuel Injector Service

White Smoke Indicates a Faulty Fuel System: Time for a Fuel Injector Service


The key of longevity for any engine is regular maintenance. Any time you see a change in the behavior, you need to address it. It might be a small problem, it may be the beginning of a huge issue, but either way, a quick reaction will ensure that the engine life is not compromised and that the costs to you are not unnecessarily high. So, what to do if the tailpipe is bellowing white smoke? And I don’t just mean a slight whiff of smoke when starting, or when the engine is at maximum load, I am talking regular usage white smoke. During really cold weather, it is reasonable to expect some, but an engine running at full power should show no visible smoke. If it does, it is time for a fuel injector service.

Faulty fuel system Fuel injector service


Possible causes

The white smoke is a result of combustion temperature in your engine being too low. To be more specific, the white smoke you see is your diesel fuel, unburned, or only partially burned. The commonest reasons for this lie in the fuel system. They range from faulty fuel injectors to retarded fuel injection timing, or even low compression.

Injector pump timing

The commonest cause of white smoke is likely injector pump timing. In order to function properly, a diesel engine needs precise timing of the injector pump and high pressure. So, any decrease in the pressure or delay in the fuel delivery to the combustion chamber will result in incomplete combustion, leading to white smoke. The incorrect timing can be caused by a worn out timing gear or a damaged crankshaft keyway.

Faulty fuel injectors

Faulty fuel injectors are also known to cause white smoke. This occurs when the fuel injector does not spray the appropriate amount of fuel into the combustion chamber. This usually makes an engine a lot louder than normally. In this situation, the best course of action is a fuel injector service, to isolate the faulty injector, and replace or repair it.

Low pressure in the fuel pump

Similarly to the fuel injectors, low pressure in the fuel pump can also lead to white exhaust. This mainly comes to be when air or other things get into the fuel line. The engine with a faulty fuel pump will be a lot quieter, but it will also have a lack of power, often stuttering when revved.

Low cylinder compression

Low cylinder compression is another, albeit not so common cause of white plumes. This is a problem which can have many causes. Broken or leaking valves are among top causes of low compression, but far from only culprits. The cylinders or the rings on the cylinders might be worn from use, which requires replacing them promptly. Yet another option is cylinder glazing, which is basically a patina of sorts coating the cylinder. The only help here is cylinder honing.

The solution

As said at the start of this text, the problem might be a really simple one, like air getting into the fuel supply, which you can mend easily. However, there might be a more serious situation, when water enters the system. This is usually a result of faulty head gaskets or cracked cylinder heads or blocks. The treatment for this kind of failure is often really expensive.

Whatever the cause of white smoke in your diesel engine is, you need to check it, before the situation escalates. Regular diesel engine maintenance should prevent these situations from ever occurring, but be sure to note any change in the behavior of the engine. It could have far-reaching consequences further down the line. Treat your engine well, and it will serve you for a very long time.

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