6.7 Cummins Surging at Idle: How to Fix the Issue

A 6.7 Cummins surging at idle may be caused by a faulty fuel pump actuator. Other potential causes could include a vacuum leak, fuel delivery problem, or ignition problem.

It is important to check for fouled plugs and ensure proper timing. The surging may also be normal during a warm-up period due to the intake grid heaters. However, if the surging persists or worsens, it may be necessary to seek further diagnosis and repairs.

6.7 Cummins Surging at Idle: How to Fix the Issue

Credit: www.dieselpowerproducts.com

1. Understanding Surging At Idle

Understanding surging at idle is essential for diagnosing and resolving engine performance issues. Surging at idle refers to the irregular fluctuation of engine speed when the vehicle is stationary. It can manifest as a slight rpm increase or decrease and can be accompanied by a jerking or shaking sensation.

Various factors contribute to surging at idle, including:

  • Faulty fuel pump actuator
  • Vacuum leaks
  • Fuel delivery problems
  • Ignition issues
  • Plugs fouling

This surging can negatively impact engine performance, resulting in power loss, decreased fuel efficiency, and rough idling. It is crucial to address surging at idle promptly to prevent further damage to the engine and ensure optimal vehicle operation.

2. Troubleshooting Surging At Idle

One common issue that may cause a 6.7 Cummins engine to surge at idle is a vacuum leak. It is important to check for any vacuum leaks in the system, as this can disrupt the air-fuel mixture and cause the engine to fluctuate in idle. Another potential cause of surging at idle is a problem with the fuel delivery system. This can include issues with the fuel pump or the fuel injectors. Inspecting the ignition system is also crucial, as a faulty ignition coil or spark plug can lead to surging. Additionally, analyzing the condition of the spark plugs can provide insights into the engine’s performance. Other potential issues to consider include dirty or clogged air filters, a malfunctioning EGR valve, or a boost leak. These factors can all contribute to surging at idle and should be thoroughly examined before concluding the troubleshooting process.

3. Fixing Surging At Idle

Surging at idle is a common issue in 6.7 Cummins engines. There are several steps you can take to fix this problem. Firstly, check for any vacuum leaks in the engine. These leaks can cause an imbalance in air/fuel mixture and result in surging. Next, address any fuel delivery problems. A faulty fuel pump actuator can cause an engine surge, so make sure to inspect and replace it if needed. Ignition issues can also lead to surging, so check the condition of your spark plugs and clean or replace any fouled plugs. Finally, consider additional measures such as checking the EGR valve or looking for boost leaks. Taking these steps should help resolve the surging issue and restore smooth idle to your Cummins engine.

Frequently Asked Questions Of 6.7 Cummins Surging At Idle

What Causes A Cummins To Surge?

A Cummins engine may surge due to a faulty fuel pump actuator. Other possible causes include a vacuum leak, fuel delivery problem, or ignition problem. It may also be normal behavior caused by injector pump fueling pulses or intake grid heaters during warm-up.

What Is Sudden Idle Surges?

Sudden idle surges are usually caused by a vacuum leak, fuel delivery problem, or ignition issue. It can also be caused by intake grid heaters kicking on and off during warm-up.

How Do You Turn The Idle Up On A 6.7 Cummins?

To turn up the idle on a 6. 7 Cummins, you can adjust the throttle stop screw on the engine’s throttle body. However, it is recommended to consult a professional mechanic or refer to the vehicle’s service manual for specific instructions.

It is important to note that modifying engine settings may affect performance and can void warranties.

What Should Cummins Idle At?

The ideal idle speed for a Cummins engine should be set between 600-800 RPM.


A surging idle in a 6. 7 Cummins engine can have several causes. It could be due to a faulty fuel pump actuator, a vacuum leak, a fuel delivery problem, or an ignition issue. It’s important to diagnose the specific cause to effectively address and resolve the issue.

If you’re experiencing a surging idle, it’s recommended to consult with a professional diesel mechanic to accurately diagnose and fix the problem.


  • Mr Shamrock

    With more than two decades in the automotive world, Mr_Shamrock is Truckguider's go-to expert for Ford and Chevy Trucks. From the F-150 to the Silverado, his breadth of knowledge covers a wide range of models, making him a reliable resource for buyers, owners, and enthusiasts alike. His expertise is also featured in online communities like Truck Forums, where he offers valuable advice and reviews.

Similar Posts

Leave a Reply

Your email address will not be published. Required fields are marked *