Fuel Injection-Diesel

Fuel injection is the system where fuel is sprayed into the combustion chamber of an engine similar to an aerosol. Until the 1990s, most car engines used carburetors, which relied on the engine ‘sucking’ the petrol in.

The primary difference between carburetors and fuel injection is that fuel injection atomizes the fuel by forcibly pumping it through a small nozzle under high pressure. Diesel engines use direct fuel injection and the injector on a diesel engine is its most complex component and has been the subject of a great deal of experimentation. Getting the fuel and air ‘mist’ circulated in the cylinder so that it is evenly distributed means some diesel engines have devices to swirl the air around in the combustion chamber or otherwise improve the ignition and combustion process.

Unlike petrol injectors, diesel injectors are not so prone to deposits that block the nozzles or affect fuel atomisation. In fact, the symptoms that many attribute to dirty injectors – loss of power, missing on start up, poor running, increased fuel consumption and exhaust smoke – are usually related to other engine issues. But because fuel injectors use very high pressure, they wear out easily and so you need to be able to tell the difference between a worn injector and a dirty one – which takes proper training and the right tools.

Sadly, experts agree that there are no user serviceable parts in diesel injectors and pumps – they need too much specialist calibrating to take apart and clean or replace. If you are going to do any DIY fuel system repairs, limit it to replacing the fuel filter and leave the fuel injection to the experts.