Fuel Line Maintenance For Lbz Duramax: Parts Replacement Guide

The LBZ Duramax is a General Motors-manufactured diesel engine used in Chevrolet and GMC trucks. Owners of these vehicles have reported issues with the fuel lines, including leaks and dry rot. To fix these issues, it is recommended to replace the entire fuel line assembly, including the fuel cooler, sending unit, and lift pump. While it is possible to replace just the leaking connector or line, it is often more cost-effective to replace all the fuel lines at once, as they tend to deteriorate over time. This can be done with either OEM replacement parts or with rubber fuel injection hose, which is easier to snake through the truck and less prone to corrosion.

Replacing rubber fuel lines with OEM parts

The rubber fuel lines in your LBZ Duramax can be replaced with OEM parts, and it is recommended to replace the entire set if one hose is found to be leaking. This is because the hoses often crack and deteriorate over time, which can lead to leaks and hard-starting issues.

Steps to Replace Rubber Fuel Lines:

• Purchase a replacement fuel line kit that matches your Duramax model. Make sure it includes all the necessary engine-related fuel supply and return hoses.
• When you have the new fuel lines, park your vehicle on a level surface and engage the parking brake.
• Raise the vehicle using a jack and support it with jack stands for safety.
• Locate the fuel lines and identify the type of fittings used. They may be spring clamps or permanent crimps.
• If the fittings are spring clamps, use pliers to squeeze the tabs and slide them back to remove the hose.
• If the fittings are permanent crimps, use a Dremel tool with a small cutting wheel to cut through the crimps, being careful not to damage the metal tubing.
• Once the old fuel lines are removed, clean the area to ensure no debris falls into the fuel system.
• Install the new fuel lines, ensuring they are securely connected and routed correctly.
• Re-attach any components that were removed for access, and lower the vehicle.

Tips and Recommendations:

• It is recommended to use high-quality, fuel-rated rubber hose for the replacement. Gates Barricade fuel hose is a popular choice and can be found on eBay or at auto parts stores.
• When in doubt, consider seeking assistance from a professional mechanic or a trusted auto repair shop.
• Keep in mind that the fuel system is under pressure, so exercise caution when working on any part of the fuel lines.

By following these steps and tips, you can successfully replace the rubber fuel lines in your LBZ Duramax with OEM parts, ensuring a reliable and leak-free fuel system.

Fuel line leaks

One of the most common areas for leaks is the fuel line right above the gas tank before the fuel sending unit. This can be replaced, along with the sending unit and fuel cooler, to prevent further leaks. It is recommended to replace all the engine-related fuel supply and return hoses, as leaks in one hose can lead to leaks in others.

When replacing fuel lines, it is important to consider the type of material used. Some LBZ Duramax owners have replaced their metal fuel lines with rubber fuel lines and clamps, which can be more flexible and resistant to leaks. However, this can be a challenging task, especially if the truck is not on a lift.

To replace the fuel lines, it may be necessary to cut the old lines with tube cutters and separate them from the rubber hose junctions. It is also important to consider the use of a lift pump, which can improve fuel flow and prevent leaks.

In some cases, fuel line leaks may be due to improper sealing or imperfections in the compression fittings. Cleaning the threads and connections of the fuel lines can sometimes resolve these issues. It is also important to check for any debris or burrs in the hardline's threads, as these can cause leaks and should be smoothed out.

Fuel line cracks

There are a few options available when it comes to replacing the fuel lines on the LBZ Duramax. One option is to purchase a full stainless steel kit, which includes all the necessary lines and fittings. This can be a costly option, but it ensures that the entire fuel line system is upgraded and can prevent future leaks. Another option is to replace individual lines as they leak, using rubber fuel lines or a braided hose kit.

When replacing the fuel lines, it is important to consider the type of fittings and connectors used. Some lines may have crimped fittings, while others may use spring clamps or barbs. It is also important to note that accessing the fuel lines may require lifting the bed of the truck or dropping the fuel tank, which can be a time-consuming process.

To prevent future issues with fuel line leaks, it is recommended to use high-quality fuel lines that are designed to resist deterioration and cracking. Additionally, ensuring that the fuel tank is clean and free of debris can help to prolong the life of the fuel lines.

Fuel hose sizing

When it comes to fuel hose sizing for the LBZ Duramax engine, there are a few different hoses and lines that need to be considered. The fuel hose size can vary depending on the specific application and location on the engine. Here is a detailed guide to help you choose the correct fuel hose size for your LBZ Duramax engine:

Fuel Line Sizing:

The fuel lines on the LBZ Duramax engine are typically made of rubber or stainless steel and are known to deteriorate over time, leading to leaks. The factory fuel line sizes for the driver's side fuel lines that connect to the fuel cooler are 1/2" for the feed line and 3/8" for the return line. These lines can be replaced with stainless steel lines and fittings for improved durability.

Fuel Filter Housing:

For a 2012 3500 model, the fuel hose size from the filter housing to the metal pipe is 1/2" for the supply line and 3/8" for the return line. However, some sources suggest that both hoses on the fuel filter head are 1/2". It is recommended to use diesel fuel-compatible hoses and worm gear clamps for proper installation.

Fuel Rail and Return Hose:

The fuel rail to fuel return hose for the LBZ engine is available as a replacement part and ensures a proper fit and function. The injection pump return hose and injection pump inlet hose are also available for the LBZ engine and fit models from 2006 to 2010. These hoses are made of high-quality rubber and are designed to resist deterioration.

Fuel Supply and Return Hoses:

The LBZ Duramax engine also requires fuel supply and return hoses, which are often moulded and can crack or deteriorate over time. It is recommended to replace the entire set if one hose is leaking. High-quality replacement hoses are available, featuring multi-layer braided construction and engineered to work with modern fuels.

It is important to verify the specific hose requirements for your LBZ Duramax engine, as there may be variations depending on the model year and vehicle application. Always refer to manufacturer recommendations and choose fuel-compatible hoses and fittings to ensure reliable performance and prevent leaks.

Fuel line connectors

When replacing the fuel lines on an LBZ Duramax engine, it is recommended to replace all the hoses in the set, as they tend to deteriorate over time, leading to leaks. The fuel line connectors are often crimped on, and special tools may be required to release them. For example, the Lisle 37000 multi-tool set can be used to disconnect the fuel line between the tank and the front of the vehicle.

Some connectors may have safety clips that need to be popped off before the tool can be inserted to release the connector. The correct size tool should be used to ensure a proper release of the connector without causing damage. In some cases, a Dremel tool with a small cutting wheel can be used to cut through the crimps, being careful not to damage the underlying metal tubing.

When replacing the fuel lines, it is important to consider the type of fuel being used. Modern low-sulphur and biofuels may require different types of hoses than those originally installed on older vehicles. It is recommended to use high-quality, flexible, and leak-free hoses that are resistant to UV and ozone deterioration.

Frequently asked questions