Dispelling the myths around fuel injector cleaners:

Diesel fuel injectors function very differently to petrol injectors and at far higher pressures up to 25,000 psi can be normal in modern common rail diesel vehicles. Due to their design, function and the higher fuel pressures, diesel injectors tend not to develop any build ups of unwanted contaminates within the injector or fuel injection system.
Symptoms that are often attributed to dirty injectors: loss of power, misfiring on start-up, vehicle generally running poorly, increased fuel consumption, excessive black exhaust smoke or blue exhaust smoke are often not related to injector cleanliness or deposits at all and are often early signs that an injector/injectors or the fuel pump are worn and will soon need replacing.

Given the precise metering required to inject the correct amount of fuel at these extreme pressures the injector components have extremely fine tolerances and after time are susceptible to wear. This means diesel injectors must have their nozzles and/or other components replaced at semi regular intervals.
Here at United Fuel Injection we have seen injectors that last 20, 000km’s and injectors that last 300, 000km’s, it all depends on the quality of fuel being used, the regularity of engine operation and combined with a bit of luck (or sometimes bad luck) as well. In general, most common rail diesel injectors that have had good quality fuel and no contaminates through the system generally tend to last around the 160, 000km to the 240, 000km range.

Chemical cleaners and fuel system flushes may assist in cleaning the fuel injection system, or they may just loosen any existing build-ups which are then pushed through at full pressure through the entire system, potentially damaging the fuel injection system, engine, or both. Chemical cleaners will not restore or improve the performance of a worn injector or improve any other underlying mechanical issues. If you choose to follow the cleaning route, be prepared that it may not improve the issue and could certainly worsen the issue.


So how do you tell the difference between dirty injectors and worn injectors?

The only proper way to determine this is to take the vehicle or the injectors to a diesel injection specialist like United Fuel Injection. We will remove the injectors from the vehicle and test them on our state-of-the-art test benches and measure the injector values to see whether they are performing within the recommended factory parameters or not.

Unfortunately, there are no user serviceable parts in diesel injectors and pumps. If you are going to do any of your own fuel system repairs or maintenance your best bet is to stick to checking and/or replacing the fuel filter at regular intervals, regular oil and oil filter changes and ensuring you do your best to never run contaminated fuel. Most general repair workshops and mechanics do not have the technical know-how and specialised equipment to repair or service diesel fuel injection components. Instead, they will often send the vehicle to us to diagnose and repair.

Other potential mechanical issues:

A refreshened or new fuel injection system still depends on a properly functioning engine to deliver the desired performance, before overhauling a fuel injection system ensure that the rest of the vehicle is in a overall good condition and none of the following issues are present:
 

• Ensure there are no warning lights or fault codes displayed on the instrument cluster. If there are, connect a diagnostic tool and repair any faults, clear codes and repeat until the warning light disappears.

 

• Low or uneven compression can produce similar symptoms to worn injectors. Diesel compression tests are different to those carried out on petrol vehicles and require specialized equipment that the average person usually will not have access to. United Fuel Injection can conduct diesel compression tests at our workshop if required and advise based on the test results.

 

• Assess the overall condition of the engine. A worn engine won’t run efficiently therefore reducing performance/output and fuel economy.

 

• Check for a deteriorated, partially blocked, or blocked fuel filter. Replace your fuel filter at regular service intervals.

 

• Check proper glow plug operation (particularly in winter) if the vehicle is hard to start or if the engine doesn’t start properly (misfiring, not running on all cylinders etc) then it may be time to install new glow plugs.

Tips to avoid fuel injection system issues:

While it’s almost impossible to avoid the normal and expected wear on your fuel injection system through time and usage, the following are some forms of insurance you can take to avoid or limit these issues:
 

• Our number one recommendation to protect your vehicle’s fuel injection system on a modern diesel engine is to purchase and install a secondary fuel filtration and water separation unit. Our recommendation and what we have fitted in our company vehicles is the Fuel Manager. The Fuel Manager will separate any water and larger contaminates out of the fuel before then running into your factory fitted fuel filter which will be a finer filter than the Fuel Manager and will capture any of the remaining fine contaminates in the fuel. You can read more about the Fuel Manager here or purchase your Fuel Manager kit from us here. These kits are bolt on and vehicle specific you simply require a few basic tools to install.

 

• If this does happen, ensure you keep at least a litre of the suspect fuel. The company involved may want to have it tested. Collect samples in clean, dry, sealable and fuel safe containers. Used plastic oil, fruit juice or similar containers are not suitable. 

 

• Don’t purchase fuel purely based upon price. Dirty, poor quality or contaminated fuel will quickly damage your fuel injection system and potentially cost thousands of dollars in repairs. Common Rail systems are far more vulnerable to poor quality fuel than the older mechanical fuel injection systems.

 

• As mentioned earlier in this article the fuel filter is vital to protecting the fuel injection system, so ensure to regularly inspect and replace the filter. We recommend to only use OEM (original equipment manufacturer) or quality and reliable aftermarket filters.

 

• If installed on the vehicle, regularly drain water traps. Particularly in rural and remote areas it is worth checking the water trap at regular intervals even if the warning light in the cabin has not illuminated.

If you had any questions or suspect your vehicle may have worn injectors, contamination in the system or any other fuel injection issues give United Fuel Injection a call on (08) 9259 3000 and talk to our light automotive department.