Cummins ISC/ISB Diesel Fuel Injectors: Signs of Failure

Is your Cummins diesel engine not performing like it used to? There's a chance that you might be having problems with your fuel injection system.

As you probably know, properly functioning fuel injectors are vital to keeping your engine running like it should. And some problems with your fuel injectors can lead to other failures in your engine. This means that fuel injector issues are something you'll want to take care of right away. 

So, how do you know if you're having problems with your fuel injectors? We've put together a list of symptoms you might be experiencing, as well as some common causes of fuel injector failure. Don't let problems with your injectors slow you down!

Check out our video for a closer look at the signs of failure in your Cummins ISC or ISB diesel engine:



Highway & Heavy Parts is here for your fuel injector needs! We have ASE certified technicians on staff who can get you the parts you need for your diesel engine.

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Symptoms of Failing Cummins Fuel Injectors


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Like with any diesel engine failure, there are some symptoms that can clue you in that you have some failing injectors. These include:

  • Excessive Smoke
  • Power Loss
  • Rough Idle
  • Fuel in Oil
  • High Return Fuel
  • No Start

Some of these symptoms might be a sign of a larger problems. For example, poor idling might be caused by corrosion on your injectors. If this is the case, you might have water contaminating your fuel, which can lead to other issues in your engine. You can read our post to learn what else can happen if your fuel is contaminated

If you notice any of these symptoms, you should look into whether or not it's time to replace your injectors.


What's Causing Your Cummins Fuel Injectors to Fail?

Diagnosing your failure isn't the only thing you should do if you're having diesel engine problems. You should also try to find out the cause of the failure so you can prevent it from happening again.

While other things can cause problems for your Cummins fuel injectors, there are some common causes of failure that you can watch out for and try to prevent. These include:

  • The Quality of Your Diesel Fuel: Fuel quality definitely has an impact on the performance of your injectors, and poor quality or contaminated fuel can cause you some serious problems. Try to steer clear of cheap fill up locations. There is a risk that the fuel could have sat for a long time, leading to contamination. Instead, try to fill up at placed that move large quantities of fuel. 
  • Operating Conditions: Keep an eye on the operating  conditions of your diesel engine. Some can negatively impact your fuel injectors, such as short runs, excessive idling, cool operating, and light engine loadings. These conditions can cause deposit problems in your combustion chamber, exhaust spaces, turbocharger, and DPF filter.
  • High Pressure/High Temperature: These can degrade your fuel and leave deposits in pumps and injectors. This, in turn, lowers the lubricating ability of your fuel.

Want to know even more details about common causes of fuel injector failure? Read our post, Diesel Engine Common Rail Fuel Injectors: Potential Failures & Causes.


What Can You Do About Failed Injectors?


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So you need new injectors for your Cummins diesel engine? Highway & Heavy Parts can help you restore your fuel system to prime operating conditions!

We have injector options for your Dodge Cummins ISB 5.9L engine and your Cummins ISC 8.3L engine.


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Been burned by injectors in the past? Well, these injectors were crafted to strict OEM specifications. Quality is the name of the game! 

Want long-lasting strength and durability? These parts are equal or better quality as those you would get from the OE. And they're backed by a 1-year parts warranty. Give us a call to see if these injectors are just what your Cummins ISC or ISB needs!


Looking for fuel injectors or other diesel engine replacement parts? We have ASE Certified Technicians on staff, ready to help! Call us at 844-304-7688, or request a quote online!