Jerry Heasley
November 1, 1997

Step By Step

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Empty? How could it be empty?? I just filled it!
Time for a new sending unit, that’s how...
You’ll have to remove the gasoline tank to get to the sending unit inside. Prior to removal, drain as much fuel as possible from the tank. Danny’s 1967 had a drain plug, but it was rusted and would not open.
Another way to drain the gas is to disconnect the rubber fuel line at the back of the tank. Pinch off the rubber gas hose and insert a makeshift rubber drain hose, plugged with a bolt, into the top of the tank.
Unplug the electrical connection at the back of the tank.
Pull everything out of the trunk, from the spare tire to the trunk mat.
Danny’s car came with the pop-open gas cap.
His son David removed the four screws that secure it from the outside.
Remove the fuel-tank filler hose inside the trunk. Wire-style clamps are stock, as seen on top of this hose. The bottom clamp is an aftermarket style that needs to be replaced to be factory.
Pull the metal fuel-tank filler neck.
Eleven equally spaced 3/8-inch bolts, plus two 1/2-inch bolts (nearest the taillight panel) secure the gas tank.
Lifting out the gasoline tank is a two-person job because the tank will still have a gallon or two of fuel left.
Turn the tank over, and with a hammer and punch, tap off the retaining ring to the sending unit.
Save the retaining ring. You’ll have to reuse it.
Pull out the old sending unit and inspect it.
Lube the new O-ring for the sending unit. This is the new fuel-tank sending unit from Dallas Mustang that includes a fresh O-ring and hose.
This is the new fuel-tank sending unit from Dallas Mustang that includes a fresh O-ring and hose.
Feed the new sending unit into the tank, float first.
Make sure the O-ring is still in its groove. Hand snug the retaining ring and tap it tight with a punch.
Dropping the new, empty tank into the trunk is a one-person job. Replace the metal fuel-tank filler neck. Then, replace the gas cap.
Replace the metal fuel-tank filler neck. Then, replace the gas cap.
Underneath the car, replace the short rubber fuel line at the back of the tank. The old one on the right is in poor condition and is not the correct length. The new hose came with the new gas tank. Be sure to plug the sending unit into the wiring harness connection.

After a fill up, the gas gauge in Danny Walker’s 1967 Mustang convertible still read empty. He hoped the fix would be as simple as replacing the gauge, but experience with vintage Mustangs told him differently. Today, a great many 30-year-old fuel-tank sending units have failed. Located inside the tank, this apparatus uses a float to detect fuel level. With a full tank, the float rides on top of the fuel. With an empty tank, the float sinks to the bottom. Its position is transmitted by electrical signals to the gas gauge on the instrument panel. The float in Danny’s car would no longer float. It stayed on the bottom. The fix is to pull the tank and replace the sending unit inside. Danny also replaced the entire tank because it was full of big chunks of rusty metal. So, even if your sending unit is still working fine, you may be surprised to learn that your gas tank has a substantial amount of rust inside that can clog up your fuel system. Here’s how to remove and replace the sending unit and gasoline tank in your 1965-68 Mustang.