Replacing The Fuel Pump In Your 1998 Chevy Blazer

Replacing the fuel pump in a 98 Chevy Blazer is a moderately complicated job. The fuel pump is located inside the fuel tank, so to replace it, you'll need to drop the tank or cut a hole in the floor of the vehicle. While cutting a hole in the floor is an option, it is not recommended as it weakens the structure of the vehicle and makes it difficult to carry heavy loads. Additionally, you risk rusting out the floor of your vehicle. The best course of action is to drop the tank and replace the fuel pump assembly, including the O-ring, pump, and strainer. It is also recommended to replace the fuel filter to give the whole fuel system a tune-up. This job is best performed by a certified mechanic or at a dealership's service department.

Disconnect the negative battery cable

To disconnect the negative battery cable of your 1998 Chevy Blazer, you will need to take the following steps:

Firstly, locate the negative battery cable. This will be attached to the negative terminal of the battery, which is usually clearly marked with a minus sign or the letters 'NEG'. Once you have located the cable, proceed to the next step.

Before you begin, it is important to ensure your safety. Make sure that you are wearing appropriate protective gear, such as gloves and eye protection. You should also disconnect the positive battery cable before proceeding, to reduce the risk of electrical short circuits. Now, you are ready to disconnect the negative battery cable.

To disconnect the cable, you will need to loosen the nut or bolt that secures it to the battery terminal. You can do this using a suitable wrench or socket. Be careful not to drop the nut or bolt inside the engine bay, as it may be difficult to retrieve. Once the nut or bolt is removed, simply pull the cable away from the terminal.

It is important to note that you should never disconnect the negative battery cable while the engine is running, as this could cause damage to the vehicle's electrical system. If the cable is disconnected while the engine is off, some electronic components may need to be reset, such as the clock or radio presets.

Now that the negative battery cable is disconnected, you can proceed with the next steps of changing the fuel pump in your 1998 Chevy Blazer. Remember to reconnect the cable securely once you have completed the fuel pump replacement, and ensure that all tools and safety gear are accounted for before starting the engine.

Relieve the fuel system pressure

To relieve the fuel system pressure, follow these steps:

First, disconnect the negative battery cable. Next, remove the cap and wait a couple of hours before replacing the pump. You can also refer to the Fuel Pressure Release Procedure.

To ensure safety, make sure to cover the regulator and the fuel line fittings with a shop towel before disconnecting. Place the towel in an approved container once the disconnection is complete. Loosen the fuel filler cap to relieve the tank vapor pressure.

Now, connect the gauge J 34730-1A or its equivalent to the fuel pressure connection. Remember to wrap a shop towel around the fitting while connecting the gauge to avoid spillage.

Install the bleed hose into an approved container and open the valve to bleed the system pressure. The fuel connections are now safe for servicing. Finally, drain any remaining fuel from the gauge into an approved container.

Remove the fuel tank and sender assembly

To remove the fuel tank and sender assembly of a 1998 Chevy Blazer, you will need to first disconnect the negative battery cable. Next, relieve the fuel system pressure. You can do this by removing the gas cap and waiting a couple of hours, or by using a fuel pressure gauge.

Once the system pressure has been relieved, you can then start to disconnect the fuel tank filler neck from the fuel tank. You will need to support the fuel tank with a jack during this process, as once the tank is freed, it will drop from the frame.

The next step is to remove the fuel tank shield by turning its hex-head bolts in a counter-clockwise direction. With the shield removed, the tank's bolts are now accessible. Disconnect the electrical and fuel line connections to the tank's fuel pump, located at the top center front of the tank. There will be two or three different-sized fuel lines and one wiring adapter plug that must be disconnected. The hoses come off by pinching or unscrewing their hose clamps, and the plug can be simply pulled out once its catch is depressed.

Now, you can start to lower the fuel tank. Extreme care must be taken during this step as the fuel sender is made of plastic and may be damaged when lowering the tank. Once the tank has been lowered, disconnect the fuel and vapor hoses and the electrical connections at the sender.

Finally, remove the fuel sender and seal ring using a specialized tool. The old seal ring should be discarded and replaced with a new one.

Install a new seal ring

To install a new seal ring, first, purge the tank if it is being repaired. Then, install a new seal ring. Do not fold or twist the strainer when installing the sending unit, as this will restrict fuel flow. Reinstall the sender using tool J36608.

Next, raise the tank slightly. Reconnect the fuel and vapor hoses and the electrical connections at the sender. Ensure the ground strap is also reinstalled to the body. Then, raise the tank fully.

Reinstall the fuel tank filler neck to the tank. The strap nuts must be tightened by steps, alternating between the four nuts until the specified torque is reached. Otherwise, the bottom of the tank will flex upward, and the fuel gauge will indicate fuel remaining in the tank when the tank runs dry.

Install the fuel tank brackets with insulator strips in place. Tighten the strap nuts to 45 Nm (33 lb. ft). Install the fuel tank shield. Reinstall the fuel tank filler cap. Reconnect the negative battery cable.

If a memory retention device was not used, reset all devices that lost their memory after the battery was disconnected. Finally, check for leaks.

Reinstall the sender

To reinstall the sender, you will need to follow these steps:

Firstly, ensure that you have a new seal ring ready to install. Place the new seal ring into position. It is important not to twist or fold the strainer when installing the sending unit, as this action will restrict fuel flow. Next, use tool J36608 to reinstall the sender.

Once the sender is in place, you can begin to raise the tank. Reconnect the fuel and vapour hoses, as well as the electrical connections at the sender. Ensure that the ground strap is also reinstalled onto the body. Now, the tank can be fully raised. Reinstall the fuel tank filler neck to the tank.

It is important to tighten the strap nuts in a specific way. To do this, tighten them in steps, alternating between the four nuts. Continue this process until the specified torque of 45 Nm (33 lb. ft) is reached. If you do not tighten the strap nuts in this way, the bottom of the tank will flex upward, and the fuel gauge will indicate that there is still fuel in the tank when it is actually empty.

Now, you can install the fuel tank brackets, ensuring that the insulator strips are in place. Tighten the strap nuts to 45 Nm (33 lb. ft). Install the fuel tank shield. Finally, you can reinstall the fuel tank filler cap and reconnect the negative battery cable.

Frequently asked questions