Replacing The Fuel Tank Sending Unit In Your '71 Vette

Replacing the fuel tank sending unit on a 1968-1982 Corvette is a relatively easy job that can be done in approximately 1-2 hours. The process involves disconnecting the battery, removing the spare tire and carrier, draining the fuel tank, and manipulating the various components around the fuel tank. It is important to work in a well-ventilated area and wear eye protection when performing this task due to the presence of gasoline fumes. Additionally, it is recommended to drain as much fuel as possible from the tank before beginning the replacement process.

Disconnect the battery and remove the spare tire and carrier support

Disconnecting the battery is an important first step when replacing the fuel tank sending unit of a 1963-1982 Corvette. This is a safety precaution as you will be working around gasoline fumes. It is also recommended to wear safety goggles and work in a well-ventilated area.

Removing the spare tire and carrier support is also necessary to access the fuel tank. Here is a step-by-step guide:

• Remove the spare tire and tire carrier. This will give you better access to the fuel tank and sender unit.
• Loosen and remove the bolts holding the spare tire carrier in place. The carrier latch support assembly and four additional bolts usually hold it in place.
• Once the carrier is removed, you will have better access to the fuel tank and sender unit.
• If your Corvette is a 1974 model or older, the sender unit will be at the bottom of the tank. For 1975 and newer models, the sender unit will be on top of the tank.
• Before removing the sender unit, it is recommended to drain the fuel tank or siphon the gas out. This will make the job safer and easier.
• With the spare tire and carrier support removed, you will now have better access to the fuel tank and sender unit for the next steps of the replacement process.

Cut the rubber hose from the sending unit to the frame fuel line

To cut the rubber hose from the sending unit to the frame fuel line, you will need to carefully cut the rubber hose in half. This will allow you to drain the remaining fuel from the tank into a drain pan. It is important to use a drain pan that is compatible with fuel and to work in a well-ventilated area to ensure your safety.

After cutting the rubber hose, insert a 3/8 bolt into the frame line end. This will allow the sending unit end to drain any remaining fuel into your drain pan. It is recommended to cut the rubber fuel hose instead of reusing it, as it is much safer to use a new hose. Old rubber hoses can be brittle and may not seal properly, leading to potential fuel leaks.

Additionally, it is worth noting that you should always wear eye protection and safety goggles when performing this task, as you will be working with flammable liquids and there is a risk of debris entering your eyes.

Unscrew the locking ring using a locking ring removal tool

To remove the locking ring, you will need a locking ring removal tool. This is a vital tool to ensure you do not damage the oil pump rings. It is also important to note that you should never try to remove the locking ring without this tool, as sparks can cause an explosion if the seals are leaking.

The locking ring removal tool will fit the fuel tank on a variety of Ford, Chrysler, and GM vehicles. It is designed to be used with a 1/2" drive ratchet or breaker bar. Place the locking ring removal tool on the locking ring tabs and use the ratchet or breaker bar to unscrew the ring.

This process is much safer and more effective than the old method of using a hammer and screwdriver, which some people still use.

Clean the sending unit contacts and remove the spade connector

To clean the sending unit contacts and remove the spade connector, you will need a small screwdriver and a clean cloth. Begin by slipping the screwdriver into the receiving end of the spade connector. This will release the spade retainer tab. Once the tab is released, gently slide the spade connector out of the retainer. Be careful not to bend or damage the connector. With the connector removed, you can now clean the contact point. Use a clean, soft cloth to wipe away any dirt, grease, or corrosion. Ensure that you only use a gentle touch to avoid damaging the connector. Once the contact point is clean, carefully slide the connector back into the retainer and lock it into place.

It is important to clean the sending unit contacts to ensure a proper connection. A dirty or corroded connection can cause electrical resistance, leading to inaccurate fuel gauge readings or even a complete failure of the gauge. By cleaning the contacts and ensuring a proper connection, you can help ensure the fuel gauge functions correctly.

Additionally, it is recommended to replace the fuel hose and clamps during this process. Old rubber fuel hoses can become brittle and cracked, posing a safety hazard. It is much easier to replace the hose now than after everything is reassembled.

Compare the new sending unit to the old one before installing

Before installing the new sending unit, it is a good idea to compare it with the old one. Ensure that the bends and connections on the new sending unit are where they should be. It is easier to find out if there is a problem now than after you have installed it.

To test the new sending unit, connect the sending unit wires to it and re-connect the battery. Have a friend sit in the car and turn the ignition on. Watch the fuel gauge and slowly move the float on the unit. If everything is connected correctly, the dash needle should move in accordance with the float. If it does, then you know everything is fine and you are ready to re-install the sending unit. If the gauge does not work correctly, then the problem lies with the wiring or the dash gauge. Remember to disconnect the sending unit wires and the battery before continuing.

Once you have verified that the new sending unit is working correctly, carefully slide it into the fuel tank. Make sure that you place the sending unit gasket onto the sending unit before you install it. When the sending unit and gasket are in place, slide the locking ring down over the sending unit tabs. Then, take the locking ring wrench and tighten the locking ring until the locking tabs rest against the tank stops.

Frequently asked questions