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Porsche 944 Fuel Sending Unit Testing and Cleaning

How to test, clean and protect the fuel sending unit from corrosion

On the road to getting the ’89 944 Turbo back on the road, I continue to come across things that need attention. The fuel sending unit is no exception.

The fuel sending unit in the Porsche 944 is a 3 in 1 device. It’s number one job is to provide a fuel level to the fuel gauge in the gauge cluster. Second, it’s the return line for any unused fuel that was sent back to the tank. And third, it’s a pressure and moisture relief system for the fuel tank.

The fuel sending units return pipe appears to not have had any gas run through it for a long time. This is likely caused by the fact that the car hasn’t run in over 4 years and the fuel return line under the car was severely pinched. The return line was pinched so bad that I don’t think any fuel could return to the tank.

So needless to say, I took it upon myself to try and salvage it. But first I needed to test it to make sure it was even worth salvaging. Check out the video below to see what I found.

Items and Tools used in this video

Resistance Level Testing of Fuel Sending Unit

  1. Connect an ohmmeter between terminals 1 and 3 on early 944s, or G & T on later 944s, on the sender.
  2. With the float all the way down, the resistance should read approximately empty resistance (see table below for specific resistance for your model year).
  3. Slowly move the float up while watching the resistance reading. As you move the float up, the resistance should slowly decrease to approximately 3 ohms with the float all the way up.
  4. The decrease in resistance should be fairly linear and smooth. If you notice any inconsistent changes in resistance, then the sender is bad or needs additional cleaning.
  5. If the tests show bad resistance readings regardless of cleaning efforts, the sender should be replaced.

*Some of the information on this page was obtained from, This link has more information on the testing procedure from the original source.*

Fuel System Rebuild Part 1

Fuel System Rebuild Part 2

Learn more about the Porsche 944 Turbo

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