Replacing The Fuel Pump In Your 99 Gmc: Step-By-Step Guide

If your 99 GMC truck has suddenly died, you may need to replace the fuel pump. This is a complex task that requires disconnecting all the harness and fuel lines before dropping the tank. You can either drain and drop the tank, remove the bed, or cut a hole in the bed to create an access door. It is also important to check for any burning signs on the wire harness and replace it if necessary. When choosing a replacement pump, it is recommended to go with AC Delco or Delphi brands as they are known for their durability and performance.

Removing the bed vs dropping the tank

When it comes to replacing the fuel pump on a 99 GMC Sierra, there are two main options: removing the bed or dropping the tank. Here are the key considerations for each approach:

Removing the Bed

This option is generally considered to be easier and quicker than dropping the tank. It involves unbolting the bed and sliding it back or tilting it to access the fuel pump. This method is especially favourable if you have a tractor or multiple people to help with the heavy lifting. Additionally, you won't have to deal with the mess of draining and dropping the tank.

Dropping the Tank

Dropping the tank can be more of a hassle, but it may be necessary if you have equipment mounted under the bed that would hinder its removal. Ensure the tank is as empty as possible, as fuel is heavy. You'll need to disconnect the fuel lines and harness, and be cautious when handling the straps due to potential rust.

Other Considerations

Some people suggest cutting an access hole in the bed, but this may be more work and leaves you with the problem of a cut-up bed. Ultimately, the decision between removing the bed and dropping the tank may depend on your specific vehicle setup and the resources available to you.

In terms of the fuel pump itself, opting for a reliable brand such as AC Delco or Delphi is recommended to avoid having to repeat the job soon.

Fuel pump brand recommendations

When it comes to replacing the fuel pump in your 1999 GMC, there are a few brands that are recommended by GMC owners and mechanics.

One of the most frequently recommended brands is AC Delco. AC Delco is an OEM brand, which means it is the same part that was in your GMC when it was manufactured. AC Delco fuel pumps are known for their reliability and longevity, with some users reporting getting about 150,000 miles out of their AC Delco fuel pump. The brand is also endorsed by mechanics, who say that cheaper aftermarket fuel pumps have a high failure rate.

Another recommended brand is Delphi. Delphi is also an OEM brand and is said to be the same part as the AC Delco fuel pump. Delphi will be the cheaper option of the two, and some users recommend this brand as a good quality, reliable replacement.

Carter is a brand that is available at Napa and is recommended by some users. However, there are mixed reviews about this brand, with some people reporting failures and others saying they have had no problems.

Other brands that have been mentioned include Bosch, which one user reported having a bad experience with, and Napa's own brand, which is reportedly a rebranded Carter fuel pump.

When replacing the fuel pump, it is also recommended to clean the fuel tank to get rid of any contaminants.

Disconnecting the fuel lines

Before beginning, ensure your GMC truck is parked on a level surface, preferably with a jack supporting it for added stability. Place wheel chocks behind the rear wheels for safety. Also, put on safety goggles and gloves for protection.

Locate the fuel lines: The fuel lines are usually located underneath the vehicle, running from the fuel tank to the engine. They are typically made of metal or rubber and can be identified by their distinctive fuel line connectors.

Relieve the fuel system pressure: Before disconnecting any fuel lines, it is crucial to relieve the pressure in the fuel system. This can be done by locating the fuel pressure release valve, which is often found near the fuel injectors or the fuel rail. Depress the valve to release the pressure.

Disconnect the fuel lines: Start by placing a drip pan or a container under the fuel line connectors to catch any spilled fuel. Using the appropriate tools, such as a fuel line disconnect tool or a line wrench, carefully loosen and detach the fuel lines from the fuel tank and the engine. Be cautious not to damage the connectors or the lines themselves.

Label and organize the fuel lines: As you disconnect each fuel line, label it clearly to indicate its original position. This will make it easier when it's time to reconnect the lines. Place the disconnected lines aside in an organized manner to avoid confusion during reassembly.

Drain the fuel tank: If there is still fuel in the tank, you will need to drain it safely. Use a fuel siphon pump to transfer the fuel to an approved storage container. Never drain fuel onto the ground or into an open container.

At this point, you should have successfully disconnected the fuel lines and drained the fuel tank. Remember to dispose of the drained fuel properly at a designated location or recycling centre. Always refer to your GMC service manual for additional model-specific information and safety precautions.

Now, you can proceed to replace the fuel pump module or perform any necessary repairs. When reinstalling the fuel lines, ensure that all connections are secure and tight to prevent leaks.

Replacing the fuel level sensor

To replace the fuel level sensor on a 1999 GMC, you will first need to access the fuel tank. There are a few methods to do this, each with their own pros and cons:

• Removing the bed: This method is generally considered to be easier than dropping the tank. It involves unbolting and raising the bed to access the fuel tank.
• Dropping the tank: This method can be done alone, but it is important to ensure the tank is as close to empty as possible first, as fuel is heavy and can make the process more difficult.
• Cutting an access hole in the bed: This method allows you to access the tank without removing the entire bed. However, it does involve cutting into and modifying the bed, which may not be desirable for some.

Once you have accessed the fuel tank, the next steps will depend on the specific model of your GMC and the type of fuel pump it uses.

For example, if your GMC has a side-mount fuel tank, you may need to disconnect multiple harness and fuel lines before dropping the tank. As mentioned previously, it is important to ensure the tank is as empty as possible to reduce the risk of fuel spillage and to make the tank lighter and easier to handle.

Additionally, if your GMC uses a Vortec engine, the fuel sending unit and pump may be a single unit, meaning that if one component fails, the entire unit will need to be replaced.

In some cases, it may be possible to replace just the fuel pump by removing the plastic clamps that hold it in place within the sending unit. However, this may be a more complex process and could result in accidental damage to the fuel lines, so proceed with caution.

When replacing the fuel level sensor, it is important to be careful not to bend the float, as this could affect the accuracy of the fuel gauge. It is also recommended to sand down the grounding point for the pump on the frame to ensure a low-resistance connection.

Finally, it is generally recommended to keep the fuel tank above the half-full mark after replacing the fuel pump to avoid any potential issues.

Some common fuel pump brands for GMC vehicles include AC Delco, Delphi, and Carter, with AC Delco and Delphi being recommended by many GMC owners and mechanics.

Cost of replacement

The cost of replacing a fuel pump varies depending on the model of GMC and the location of the repair.

The national average cost for a fuel pump replacement across all vehicles is between $611 and $894, including parts and labor. However, the cost for a GMC Sierra 1500 Fuel Pump Replacement is estimated to be between $1,270 and $1,439, with labor costs between $189 and $238, and parts priced between $1,081 and $1,200. Meanwhile, the estimated cost for a GMC Canyon Fuel Pump Replacement is between $874 and $1,009, with labor costs between $287 and $362, and parts priced between $587 and $647.

It is important to note that these estimates do not include taxes and fees and may not be applicable to your specific location.

Additionally, some GMC owners have reported varying costs for fuel pump replacements. One GMC owner reported a total cost of $248 for labor to install a Carter pump, while another owner stated that they paid nearly $500 for a Delco pump, including the strainer and filter.

It is always recommended to consult with a local GMC mechanic or dealership to obtain the most accurate and specific estimate for a fuel pump replacement.

Frequently asked questions