Request a Password

How to Find a Clogged Fuel Injector

Posted by Scott Goldfarb on

Diesel fuel injection is a key part of any diesel engine system. Diesel fuel injection parts are the parts that ensure the engine receives the correct amount of fuel at the correct time by delivering the fuel to the cylinders as a fine mist (so it is easier to burn).

Keeping fuel injectors unclogged is critical to a functioning fuel-injected engine. If a fuel injector is clogged, it can't inject fuel, and you face a number of problems. These problems can manifest themselves in different ways, such as:

  • The engine gives off bad emissions
  • The engine does not make power or accelerates poorly
  • The engine has poor fuel consumption
  • The engine runs very rough
  • Any number of the cylinders do not fire
  • The engine does not start

All of these conditions are problematic and can indicate your engine has a clogged fuel injector.

Diagnosing a Clogged Fuel Injector

Diagnosing a clogged fuel injector can be difficult, though, because these symptoms are also indicative of dead spark plugs, bad coils, broken spark plug wires, or a different underlying electrical problem. If you suspect your fuel injectors may be clogged, follow these steps to find out for sure.

  • Let a cold engine start and then idle for five to ten seconds.
  • Turn off the engine. If the engine is warm but not hot, you can quickly touch each of the exhaust manifolds to find one that is not as warm as the others. (Drops of water on the manifolds will work, too, if they are too hot to handle. You will be able to see the water sizzling on ones that are working.)
  • On the cylinder that is not as warm as the others, remove the connector from the injector.
  • Visually inspect the injector connector terminals for corrosion.
  • A Noid light or an ohm meter can be used to check for power to the injector connector.
  • If you can confirm that the injector has the proper resistance, reconnect the injector connector.
  • Disconnect or remove the coil pack or spark plug wire that goes to this cylinder.
  • Start the engine again; it should sound the same.
  • Remove the spark plug and determine if it is wet or dry. A dry spark plug indicates that the injector is not delivering fuel to that cylinder. A wet spark plug that smells like gasoline indicates that the injector on that cylinder is not your problem.

Why Did This Happen?

Fuel injectors can become clogged for a number of reasons. Fuel typically contains ethanol, which draws moisture into the fuel. The moisture that is attracted by the ethanol can cause metal pieces it comes in contact with to rust. If a fuel filter does not do its job, residue from the rust can enter the fuel injectors and clog them.

Clogging can also occur if the diesel engine has been sitting for a long period of time with gasoline in the tank. The entire fuel system can be gummed up and will need to be cleaned.

Additionally, some service stations do not store fuel properly, and it is possible for debris and sediment to contaminate the fuel and make their way into the fuel injectors.

Unclogging a Fuel Injector

While there are additive products on the market claiming to clean fuel injectors, they don't typically provide the long-term results you want. The cleaners loosen the debris within the injector, but they will also cause additional debris to be dislodged and pushed through the pathway to the injector. It may create a temporary solution, but it is not going to solve the problem permanently if the debris is still in the injectors without a way to be completely removed.

Unfortunately, unclogging a fuel injector is not a simple process. To adequately have the injector cleaned, it should be removed and cleaned by a professional injector cleaning service. These services will not only clean the injector but also test to ensure the right amount of fuel is distributed by it. You can also take the engine to a mechanic for a full fuel injection cleaning.

If the fuel injector does not provide any resistance and gives no response when tested with an electrical input, the injector is dead. A dead fuel injector and a clogged fuel injector will present themselves the same way and lead to the same problems. Dead fuel injectors need to be replaced.

You can find fuel injector replacement parts and other diesel parts for any type of diesel engine in our online inventory or in person at our warehouse.



Leave a comment

Please note, comments must be approved before they are published


Stay up to date with our best deals by signing up for our email specials.

Weekly Specials
Join Our Newsletter
Save 10% on your next order