How to Test the Fuel Sending Unit in a 1965-1970 Mustang

How to Test the Fuel Sending Unit in a 1965-1970 Mustang

Last Updated January 11, 2024 | Bill Tumas

Knowing how much fuel is left in your 1965-1970 Mustang is obviously important. If you suspect your fuel sending unit is giving an incorrect reading, it’s important to check it. Plus, you should test a new fuel sending unit to make sure it’s working properly before you install it. Watch the video below and follow our steps to learn how to test a fuel sending unit with a multimeter.

Classic Mustang Fuel Sending Unit Testing Instructions

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  1. Grab a multimeter and set the meter up to read ohms.
  2. Ground the negative feed anywhere on the sending unit and place the positive feed on the sending unit stud. Your unit may need to be mounted upside down to access the stud. If this is the case the float will be at the bottom, which is the full tank position.
  3. Wait for a second so the reading has time to adjust. You'll see roughly 10 ohms on a full tank once the wires are connected, but that reading will vary depending on which sending unit you have. In our case, anywhere between eight and ten ohms is acceptable.
  4. Slowly raise the float and check for a change in ohms on the multimeter. As you raise the float towards empty, the reading should be around 60 ohms, or whatever your sending unit’s max reading is.
  5. As long as the readings are showing up accurately, your fuel-sending unit should be good to go.

Mechanic testing a fuel sending unit on a classic Mustang with a multimeter

Keep Your Classic Mustang’s Fuel System Flowing

Now that you know your 1965-1970 Mustang’s fuel sending unit is working, you’re ready to hit the road. Keep the rest of your Mustang’s fuel system in good working order by upgrading your fuel tank, filler pipe, and fuel lines. We’ve got all the parts you need to keep your classic Mustang fueled up and on the road.


This article was researched, written, edited, and reviewed following the steps outlined in our editorial process. Learn more about CJ's editorial standards and guidelines.