The fuel injection system is a critical component of every diesel engine. This system pressurizes and injects the fuel into air that has been compressed in the combustion chamber. The functions of a fuel injection system include feeding fuel to the injectors, adjusting the fuel quantity, adjusting the injection timing, and atomising the fuel.
The right amount of fuel must be provided at the right moment in a suitable condition for the combustion process.
The fuel injectors help improve fuel efficiency, keep emissions cleaner, and reduce the need for fuel system maintenance work. The average lifespan of a diesel fuel injector is around 100,000 miles. A typical fuel injector has two basic parts: the nozzle and the injector body. If either of these components gets clogged or damaged, it will compromise the entire performance of the vehicle.

Here are the 5 most common symptoms of faulty diesel fuel injectors.
- Trouble starting the vehicle or uneven idling. The engine cranks but doesn’t start unless you crank it for a long time. The engine is using different speeds of revs on idle.
- Misfire. If the vehicle is misfiring on ignition, a complete diagnosis involves finding the combustion process element that is lacking. In a diesel engine this is either a lack of fuel injection or a lack of combustion chamber heat. The fuel charge in one of the cylinders fails to ignite or there is a low level of fuel being pumped into the ignition.
- Smell of fuel. The smell of diesel inside the cabin means that the diesel has a leak somewhere. This could be from a faulty injector allowing fuel to flow out of the injector when it isn’t active.
- Dirty emissions. Clogged filters and injector deposits will cause an uneven or incomplete fuel burn, resulting in the area of the vehicle around the exhaust to be dirty and the release of white smoke from the exhaust pipe.
- Increased fuel consumption and poor miles per gallon. Faulty injectors burn more fuel and will directly impact your vehicle’s performance and efficiency.
Clean fuel injectors are a must for peak performance of your diesel engine. Any of the symptoms above can indicate problems with your fuel injectors which shouldn’t be ignored. These include injectors that are dirty, clogged, or have a leak. If you have put more than 100,000 miles on your vehicle without replacing the fuel injectors, it is time to have them checked out by a professional.
If you are in the Meridian, ID area, contact Gem State Diesel’s diesel engine experts for help. We can manually inspect your injectors to diagnose the problem. Any injector issues can be easily fixed by cleaning, repair, or replacement. You can call us at 208-288-5555, or fill out this online form and one of our experts will respond to you within 24 hours.