Fuel Injector – Deposits Can Build Up And Clog The Fuel Injector

Fuel Injectors - Will Usually Only Fail, In One Of Three Ways
Fuel Injectors - Will Usually Only Fail, In One Of Three Ways

A dirty or clogged fuel injector can cause classic engine problems. For instance, lean misfire, rough idle, hesitation and loss of power.

It doesn’t take much of a restriction in a fuel injector, to lean out the air/fuel mixture.

Gas is a mixture of many different hydrocarbons including, oilfins which are heavy waxy compounds.

So, when the engine is off there is no cooling airflow through the ports. Also, no fuel flow through the fuel injector to wash it away. As a result, heat bakes the oilfins into hard varnish deposits.

Consequently, these deposits can build up and clog the fuel injector. Furthermore, the formation of these deposits is a normal consequence of engine operation.

Deposits Comparison
Deposits Comparison

In addition, detergents are added to gasoline to help keep the injectors clean. But, if a vehicle is used primarily for short-trip driving, the deposits may build up faster. As a result, not letting the detergents wash them away.

On four-cylinder engines, the #2 and #3 injectors are in the hottest location. And, tend to clog up faster than the end injectors on cylinders #1 and #4. Consequently, the same applies to the injectors in the middle cylinders in six- and eight-cylinder engines.

As a result, the hotter the location, the more vulnerable the injector is to clogging from heat soak. Throttle body injectors are less vulnerable to heat soak. Because, of their location high above the intake manifold plenum.

Fuel System
Fuel System

Fuel Injector Deposits And Failure Symptoms:

  • Starting issues
  • Poor idle
  • Failed emissions
  • Poor performance
  • Engine does not reach full (RPM)
  • Increased fuel consumption
  • Rough engine performance
  • Surging and bucking under various throttle loads
  • Smoke from the tailpipe
  • Not to mention Engine Knock or Detonation. Which can lead to catastrophic engine failure.
  • Pollution

Fuel Injector Cleaning


The benefits realized by injector cleaning obviously will vary, depending on the condition of the injectors. Injectors that are really dirty, should show a good improvement in performance. Either way, performance, fuel economy and emissions should all be better after a cleaning.

Additional Signs To Watch For:

  • Restrictions
  • Turbo Troubles
  • Heat Soak
  • Also Increase or Decrease in Long- and Short-Term Fuel Trims
  • Not Enough Resistance
  • Longer Crank Times
  • Failed Balance Tests
  • Misfire Codes
  • Vehicle Won’t Start With Full Tank
  • Lack of Maintenance
Fuel Injector Firing
Fuel Injector Firing


So, high quality gasoline has detergents designed to keep injectors clean. Yes, this implies that cheap gas will take you down the fast road to clogged injectors. Finally, the equality of the fuel you use has a pronounced impact on fuel injector life and cleanliness.

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