Fuel injectors are responsible for getting fuel into the engine. Fuel injection systems either work via a throttle body containing a couple of injectors that send fuel to multiple cylinders at once, or via injectors that deliver fuel directly into each cylinder individually. The injectors themselves spray gas into the combustion chamber like a spray bottle, allowing the gas to mix with air before ignition. The fuel is then ignited and the engine keeps on moving. If the injectors become dirty or clogged, the engine struggles to run as smoothly.

How fuel injectors work

Whenever an internal-combustion engine is powered down, the combustion chambers have leftover fuel/exhaust hanging around. While the engine cools, the vaporized gases settle on every surface in the combustion chamber, including the fuel injector nozzle. Over time, this residue can reduce how much fuel the injector can deliver to the engine. There is not much you can do to prevent this, but if the engine has worked particularly hard (lots of uphills or high temperature) it may be a good idea to let it cool down a little before shutting the engine off. Driving more gently towards the end of a trip can extend the life of the fuel injectors.

Aside from the fumes and fuel itself, the fuel injectors can get clogged up by debris. This can either come from gas or from the fuel system itself. Gasoline with impurities in it is less common these days, and most major gas stations have consistently high-quality gas. Still, debris can get into the tank and then into the fuel system. The fuel filter catches the majority of impurities but a small amount may make it past the filter. If there is water in the fuel system, corrosion can happen within the lines and fittings of the fuel system. This corrosion can cause debris to be jammed in the injectors.

What services can fix this issue?

In the case of simple debris in the injectors, a fuel injection flush is a cost-effective way to improve fuel injector performance. For cooked-on residue, it usually requires a full ultrasonic cleaning to get the fuel injectors back into fighting shape. For particularly old or inexpensive injectors, replacement may be the best solution.

This article originally appeared on YourMechanic.com as What Causes Fuel Injectors to Get Clogged or Dirty? and was authored by Ian Swan.


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