Replacing a Fuel Injector

fuel injectors being taken out of an engine

All engines need air for the combustion process. Fuel injection systems have replaced the old style carburettors that previously mixed the fuel with the required oxygen and are now commonplace in most engines. There are a number of common signs that these small parts are becoming clogged or fatigued, including the detonation of petrol on the exhaust or the vehicle failing to start with a full fuel tank.

Problems with the injection system in cars that are primarily used for short run motoring can often occur due to the failure of the detergent system used to clean the valves to engage properly. However if your car’s performance does not improve after a good long run on the road you may need to replace one or more of your injectors.

Even though the injectors are an easily accessed part this is one of the harder replacement jobs to do round the car. It is best attempted by someone with a good knowledge of mechanics and a reasonable amount of experience using tools. It is important that you understand that the fuel injection system is highly pressurised.

You will need: Fine nosed pliers, fuel injector tester, and a screwdriver

Locate the Injector and Connect the Tester

Open up the bonnet of your car and locate the fuel injectors. These should all be on a rail, on top of your engine. Then find the valve on the fuel line and connect it to the fuel injector tester.

Test the Fuel Injection System

Use the fuel injection tester to find the pressure readings for each of the fuel injectors. This should allow you to locate the faulty injectors within the system and determine which need to be replaced.

Disconnect the Fuel Line

Next disconnect the fuel line completely from the engine, so that no more fuel will be pumped into the injectors. Next start the vehicle in neutral and allow it to idle for a few moments, giving the injection system some time to completely clear of fuel.

Remove the Injector Rail

Loosen the screws that hold the injector rail in place against the engine block. This should now give you access to the individual injectors.

injector being removed from an engine

Replace the Damaged or Faulty Injectors

Locate the faulty injector and remove the electrical connection, before pulling it out of its seating. Replace this with a new injector and reattach the electrical connection. Repeat this process for all the injectors that failed the initial pressure test.

Reconnect the Fuel Rail and Fuel Line

Finally use the original screws to reconnect the fuel rail to the engine block and reconnect the fuel line. This is now the ideal time to turn on the ignition, leaving the car in neutral, so that you can observe the fuel injectors working.

When you have completed the replacement work, it’s advisable to take your car out for an extended drive on the road to ensure that there is no roughness or unexpected drops in performance in the engine.

This entry was posted in Maintenance on by Justin Smith.

About Justin Smith

As the man at the helm of BreakerLink, it is no surprise that its Director, Justin Smith, has always had a keen interest in cars, bikes and most things wheeled. Having spent over two decades in the car parts industry, Justin combines his passion that since 2002, has successfully united those looking for new and used car parts with the breaker that supplies them. Follow Justin on LinkedIn.

Disclaimer: These articles are for guidance purposes only. If you have any questions regarding any matter relating to your vehicle we would recommend that you seek the advice of an appropriate professional. We accept no responsibility or liability should you suffer financial or personal damages in relation to the advice stated on this website.