Unveiling the Benefits of 6.7 Cummins Fuel Rail Plug

The Cummins 6.7L turbo diesel engine is one of the most powerful engines for pickup trucks. Fuel rail plugs have a significant role in this engine. These plugs help increase the engine’s efficiency by maintaining proper fuel pressure.

This particular part is small in size but has significant benefits. In this blog, we will show you the benefits and everything you may query about these Cummins fuel rail plugs.

What is a Fuel Rail Plug?

A fuel rail plug is a small cap that you will see in your engine, which blocks the unusual fuel ports in the rail. 

It allows the fuel injection pump to maintain the proper fuel pressure between the rails.

People use this when modifying an engine, such as upgrading the fuel system or swapping out the fuel injector. 

These plugs keep the pressure inside the rails and prevent fuel from leaking out from those unused ports.

You will find rail plugs of various sizes. They are generally made of metal or plastic.

Fuel Rail Pressure Sensor

The fuel rail pressure sensor is crucial to your vehicle’s fuel system. This sensor monitors the fuel pressure on the rails. 

It sends the pressure data to the E.C.U. After receiving the data, E.C.U. changes the fuel pressure and injection timing when it is necessary.

You will see these sensors mostly on diesel and gasoline-operated cars. Let’s see some more information about this:

Ideal Fuel Rail Pressure For 6.7 Cummins

The pressure on the rails should be optimal. High fuel pressure can cause leakage, and low pressure can cause common injector problems. 

The maximum pressure on a fuel rail can get up to 26,000 PSI. Generally, it stays between 1600 to 2600 bar.

Location of the Pressure Sensor

We often make a mistake while identifying the fuel rail sensor. The fuel tank has a pressure sensor, but that is not what we are talking about here. The fuel rail pressure sensor will be above the fuel rails.

You can quickly spot the sensor by tracking along the rails till the injectors. In most models, the pressure sensor is above the rails in front of the engine.

Read Also: What To Do If Fuel Pump Making Noise But Not Pumping Fuel?

Objectives of 6.7 Cummins Fuel Rail Plug

Well, the main objective of this fuel rail plug is to increase the duel pressure in the rails. When you tune your ECM, the fuel pressure increases to a higher number. 

Due to the pressure, the rail release valve opens. You can install the rail plug then to eliminate the valve.

So, the core objective of these plugs is to allow the pressure inside the rails and fuel injector to keep the vehicle away from low-pressure-related problem codes.  

Another purpose of this plug is to prevent dirt from getting inside the rail. Mud in the fuel rails can stop the pressure from rising and create an obstacle.

Benefits of 6.7 Cummins Fuel Rail Plug

The fuel rail plug is a part of your car’s fuel management system. It plays a vital role in keeping the pressure on inside the rails. Let’s take a look at some of the benefits of this rail plug:

Increased Fuel Efficiency

A Fuel rail plug can help to increase the fuel efficiency of your 6.7 Cummins engine. 

It helps to maintain a high pressure which helps the engine to stay and perform in an efficient way leading to better fuel economy.

Enhanced Engine Performance

The performance of the engine mostly depends on the pressure of the fuel. Rail plugs help to keep the fuel pressure high. 

When the pressure is constantly high and uninterrupted, the performance of the 6.7 Cummins engine improves a lot.

Read Also: Why Fuel Pump Won’t Turn on with Ignition? 10 Major Reasons

Improved Safety

Safety is a crucial factor that all of us consider. A faulty or low-quality part can cause massive accidents inside the engine. 

As we said earlier, fuel rail plugs eliminate the release valves. The valves can have leaks when the fuel pressure is very high. 

Plugs eliminate the threat of fuel leaks from the non-functioning ports of the rails.

Cost Saving

The owners of 6.7 Cummins engines can save money by installing a fuel rail plug. They will not require extra fuel and won’t need repairs because you will have better fuel efficiency and a low risk of costly engine damage caused by fuel leaks.

Environment Friendly

A fuel rail plug can help minimize fuel waste by preventing leaks and improving fuel efficiency. That leads to a low environmental impact on the engine operation. 

When the fuel pressure is constant, your engine will run smoothly and emit carbon in a very low amount. So, no doubt, rail plugs are environmentally friendly.

Eliminates Trouble Codes

You can face P1011 and P0087 codes on your vehicle when you have low fuel pressure regularly. 

And as you already know, rail plugs can increase the fuel pressure, eliminating these problem codes. After installing fuel rail plugs, a scanner can remove these codes. 

Read Also: Will Transmission Fluid Clean Diesel Fuel Injectors

How To Install 6.7 Cummins Fuel Rail Plug?

The installation process of the 6.7 Cummins fuel rail plug is pretty simple. That is one of the benefits of this plug. Let’s see the installation process in a few simple steps:

Step 1: Locate the plugs

First, you should find where the fuel rail plugs are. Then locate the spots where you are going to install the new plugs.

Step 2: Clean the entire area

Before you install the rail plug, you need to clean the entire area around the fuel rail plugs. 

If you don’t do that, you might leave behind some dirt which can create future problems. So, clean the whole rail area, valve, and manifold.

On your new rail plug, you will have an o-ring, and there you will see some engine oil. Clean those too, and also clean the surface of the plug.

Step 3: Remove the connections

Now, remove the existing valves or plugs you will replace with new ones. There is a valve assembly that you may need to remove also. You will need a specialized tool to do the removals. 

Step 4: Attach the new rail plugs

After removing the old ones, correctly clean the port and place the new ones there. Make sure they are correct in size and fit correctly. Now, tighten the plugs with a wrench or torque wrench.

Double-check the plugs if they are set tightly or not. After you finish, test the engine to ensure everything is functioning correctly.

Read Also: Why is the Fuel Pump Not Priming? (Causes with Fixes)

Common Complaints of 6.7 Cummins Fuel Rail Plugs

Though not often, people sometimes face issues and complaints about the 6.7 Cummins fuel rail plugs. Let’s take a look at those complaints:

  • Fuel leakage: Fuel leakage is the most common problem with rail plugs. This issue can occur if you don’t have an undersized, oversized, or damaged plug that is not properly sealing the fuel inside the rail.
  • Difficulty in removal: People often face a stuck plug situation. When the plug gets stuck in position, it becomes hard to remove during maintenance or replacement. Rust, corrosion, or damage can cause this.
  • Cracks and breaks: Rail plugs sometimes break or have cracks due to excessive pressure and heat. These damages can lead to fuel leaks or other damages also. 

Symptoms of a Bad Rail Plug

You may wonder how you will know you have a lousy rail plug. Don’t worry; your engine and the vehicle will start showing these symptoms:

  • Bad acceleration
  • Decreasing fuel injector pressure
  • Low mileage
  • Fuel leakage
  • Engine misfire
  • Emitting “check engine” light

So, when you see any of these symptoms, a bad fuel rail plug can be one of the reasons behind that issue. You can take expert advice or inspect yourself why you are having this.

How to Solve the Bad Rail Plug Issue

A bad fuel rail plug can create more significant problems for your engine. So, if you see any of the above symptoms, don’t be late to take troubleshooting steps. Here are some steps that you may take to solve a bad fuel rail plug issue:

Check the Plug Orientation

If you doubt a bad rail plug, ensure the rails plugs are correctly oriented. Make sure they are in the correct slot where they should be. 

Different rail plugs have different and specific angles and orientations. The requirements have to match for a proper fit. If you see any misoriented placement, solve the issue immediately.

Clean the Rail Plug

Dirt can be a big issue for rail plugs. Sometimes, dirt, dust, or debris can occur on the plugs and their joints. These things can decrease the efficiency of the plugs. 

If you find such issues, clean the plugs and their surroundings with a clean, dry cloth or soft-bristled brush to remove the dirt or debris. 

Replace the Rail Plug

When none of the above solutions work, you may have to change the rail plug. Replace the rail plug with a new one compatible with your vehicle’s fuel rail. Make sure you have a plug that is not either oversized or under-sized. 

Read Also: 12 Weak Mechanical Fuel Pump Symptoms You Should Know


We understand that you may still have some questions regarding this. Don’t worry; in this FAQ section, we will try answering them and clarifying your doubts.

What are the materials of a 6.7 fuel rail plug?

The fuel rail plug is made from pure T304 stainless steel. This helps the plug to hold pressure and prevent corrosion. Stainless steel makes the plug solid and long-lasting.

How do you know when the fuel pressure is decreasing?

Your engine will start to make harsh sounds, and you will notice less fuel efficiency and black smoke coming from the exhaust when the fuel pressure decreases. Because of this, you may also face slow starting, no staring, or low horsepower.

Can the fuel rail plug increase torque?

Fuel rail plugs increase the fuel pressure inside the rails. Due to this increased pressure, the torque output level of an engine increases. That means, indirectly, rail plugs help to improve this torque output.

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