Replacing Fuel Lines: A Step-By-Step Guide For Your Jimmy

If you're looking to replace the fuel lines on your GMC Jimmy, there are a few things you should know. Firstly, it's important to use the correct type of fuel line for your vehicle. While you may be tempted to use a regular low-pressure fuel line to save money, it's not recommended as the entire system is under more pressure than a regular fuel line can handle. Instead, consider using a high-pressure rubber fuel line or metal line, which can be bent using a tubing bender to match the bends in the old line. Additionally, pre-bent fuel line kits are available for the GMC Jimmy, which can make the installation process easier. These kits include everything you need for a clean and complete installation, and are designed to meet or exceed OEM requirements.

Use a tubing bender to put the proper bends in the new line

Bending metal tubing requires precision and care. The basic principles of tubing bending have remained the same for decades, but the technology used has evolved significantly. There are several factors to consider when bending tubing for fuel lines.

First, it is important to use the correct tool for the job. In this case, a tubing bender is required to bend the new fuel line for a Jimmy. The type of tubing bender will depend on the material of the tube and the desired bend. For example, ram-type bending is one of the oldest and simplest methods, using a hydraulically driven ram to force the tube against rollers or pivot blocks. This method is often used for light-gauge metal. On the other hand, roll bending uses three rolls in a pyramid shape to roll the tube through the mechanism, and is often used for large bends in construction workpieces.

Second, the properties of the tube itself will affect the bending process. The tube's material, wall thickness, and outside diameter will all play a role in how it bends. The bend radius, or centre line radius (CLR), is the standard way to measure a bend. The smaller the CLR, the sharper the bend. The bend radius also indicates the minimum radius one can bend a tube without damaging it.

Third, the desired shape of the bend must be taken into account. To achieve a 90-degree bend, for example, the tube must be marked at the beginning and end of the desired bend, as well as with a longitudinal line on the side opposite to the bend direction. A test tube can then be bent 90 degrees and used as a reference to check the accuracy of the bend.

Finally, safety is a critical consideration when working with fuel lines. It is important to use the correct type of tubing and to ensure that all connections are secure and tight to prevent leaks.

By following these guidelines and using the old fuel line as a template, one can successfully use a tubing bender to put the proper bends in the new fuel line for a Jimmy.

Cut and splice the line

To cut and splice the line, you will need to cut out the rusty or rotted portion of the metal fuel line and replace it with a new section of tubing. It is important to ensure that you have enough tubing to work with, so it is recommended to cut out a longer section of the line, approximately 12 inches or more, to provide some flexibility during the repair process.

Before making any cuts, it is crucial to relieve the pressure in the fuel system by releasing the fuel pressure in the lines. This can be done by removing the fuel pump fuse or relay and then running the engine until it stalls. Once the pressure is released, you can proceed with cutting the line.

When cutting the metal fuel line, aim for clean and flat ends. You may need to use a tubing cutter or a rotary tool with a cutting wheel to ensure a straight and precise cut. After cutting, it is essential to deburr the inside and outside edges of the tube to remove any sharp burrs or metal shavings that could impede the connection or cause leaks.

To splice the new section of tubing into the existing line, you have a few options:

• Compression fittings: You can use compression fittings specifically designed for fuel lines to join the new tubing with the existing line. Ensure that the outer diameter of the tubing is clean and free of any debris or corrosion before installing the compression fittings.
• Flaring tool: Another option is to use a flaring tool to create a bubble flare on the ends of the new tubing. This flare will help keep the fuel hose from sliding off and provide a secure connection. You can then connect the new tubing to the existing line using fuel injection-rated rubber hose and EFI hose clamps, which are designed to not cut into the outer hose.
• Metal epoxy: If you prefer a more permanent solution, you can cut and drill the rusty section of the line, and then solder or epoxy a new piece of tubing in place. This method requires cleaning the area thoroughly and ensuring a strong, leak-proof connection.

Remember to work with extreme caution when handling fuel lines, as they are under pressure and contain flammable fuel. Always take the necessary safety precautions, such as wearing protective gear and working in a well-ventilated area, to mitigate the risk of injury or accident.

Use a high-pressure rubber fuel line

When replacing the fuel lines on your Jimmy, you may want to consider using a high-pressure rubber fuel line. Rubber fuel lines are easy to install and typically use standard barbed fittings and fuel line hose clamps. However, they are not as durable as metal lines and will need to be replaced more often. Rubber fuel lines are also more susceptible to cuts, nicks, and abrasions, so they should not be used to plumb an entire fuel system.

If you decide to use a high-pressure rubber fuel line, make sure it is rated for fuel injection and can handle the pressure of your fuel system. The pressure rating of the rubber fuel line should be 25-50% above the pressure you are running. For example, if your fuel system operates at 100 PSI, you will need a rubber fuel line rated for 125-150 PSI.

It is important to note that rubber fuel lines start degrading as soon as they come into contact with fuel. They will also leak fuel vapors, which can leave your garage or vehicle smelling like raw fuel. As a result, you will need to inspect the rubber fuel lines periodically and replace them as needed.

When installing the rubber fuel line, be mindful of the length. The longer the rubber line, the more opportunity for it to sag and wear through where the rubber meets the metal. Try to use as much steel line as possible and limit the length of the rubber line. NHRA specifications limit the length of continuous rubber fuel line to 12", but some recommend keeping it to 6" or less.

Use a pre-bent fuel line kit

If you want to replace the fuel lines on your GMC Jimmy and are looking for a straightforward process, consider using a pre-bent fuel line kit. These kits are designed for easy installation and are a popular choice for those who want to replace their fuel lines without professional help.

Pre-bent fuel line kits come with everything you need for a complete installation. The lines are made of galvanized steel with plated fittings and hardware, ensuring durability and long-lasting service. The galvanized steel construction also makes the lines corrosion-resistant, which is essential for their function. Each line is CNC-bent to ensure a precise fit, and they are engineered to meet or exceed OEM requirements.

Some kits may also include high-quality flexible hoses made of materials like stainless steel or PTFE. These hoses provide added flexibility during installation and are also corrosion-resistant. The kits are packaged in heavy-duty corrugated cartons to protect the lines during shipping and ensure they arrive in perfect condition.

When purchasing a pre-bent fuel line kit, it's important to verify compatibility with your GMC Jimmy's make and model year. For example, the AGS Automotive Solutions pre-bent fuel line kit is compatible with the 1997-2004 Chevrolet Blazer 4-door and GMC Jimmy.

Using a pre-bent fuel line kit can make the replacement process much more accessible and less intimidating. With the right parts and some guidance, you can successfully replace your GMC Jimmy's fuel lines.

Check for damage to retainer clips

When replacing the fuel lines on a Jimmy, it is important to check for damage to the retainer clips. These retainer clips are provided with the replacement lines and may or may not be needed, depending on the condition of the existing clips.

If the retainer clips inside the connectors are damaged during the removal of the original fuel lines, you will need to leave the retainer clips on the replacement lines. This is because the retainer clips play a crucial role in securing the fuel lines in place and ensuring a leak-proof connection.

On the other hand, if the retainer clips inside the connectors remain undamaged during the removal process, you will not need to use the provided retainer clips on the replacement lines. In this case, simply remove the retainer clips before plugging the replacement lines into the connectors.

It is worth noting that some people have reported issues with the sturdiness of the retainer clips, mentioning that the plastic is very flimsy and the clips break easily. Therefore, it is advisable to handle the retainer clips with care during the installation process to avoid any damage.

Additionally, when checking for damage to the retainer clips, it is important to inspect the overall condition of the clips, including their size, material, and any signs of wear or fatigue. This will help ensure that the retainer clips are functioning properly and securely holding the fuel lines in place.

Frequently asked questions