How to: Inaccurate fuel gauge readings. How to rule out the actual fuel gauge.

If your fuel gauge is giving you wacky readings, it is more than likely the fuel sender (#110555). But how do you know for sure? Here is a way to test the fuel gauge to make sure it is not the culprit (courtesy Dave S at DMC Midwest):

§ Open the trunk and remove the carpet and Trunk Inspection Cover #105168.
§ Locate the fuel sender. There are three connectors on top of the fuel sender. Start with the plastic connector plugged in.
Test 1:
a. Jumper the connectors on top of the fuel sender that correspond to the green wire w/black stripe and the black ground.
b. Turn on the ignition.
c. The fuel gauge should read empty.
Test 2:
a. Remove the jumper and disconnect the plug.
b. The fuel gauge should read full.
Test 3:
a. Plug the plastic connector back in.
b. Jumper the connectors on top of the fuel sender that correspond to the light green wire w/orange stripe and the black ground.
c. The low fuel light should turn on.

If any of the three tests gave you an unexpected result, you may have a problem related to the fuel gauge or wiring etc. However, if all tests “passed”, your fuel gauge is good and the problem is most likely the fuel sender.

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Originally Posted by Henrik

If your fuel gauge is giving you wacky readings, it is more than likely the fuel sender (#110555). But how do you know for sure? Here is a way to test the fuel gauge to make sure it is not the culprit (courtesy Dave S at DMC Midwest):

§ Open the trunk and remove the carpet and Trunk Inspection Cover #105168.
§ Locate the fuel sender. There are three connectors on top of the fuel sender. Start with the plastic connector plugged in.
Test 1:
a. Jumper the connectors on top of the fuel sender that correspond to the green wire w/black stripe and the black ground.
b. Turn on the ignition.
c. The fuel gauge should read empty.
Test 2:
a. Remove the jumper and disconnect the plug.
b. The fuel gauge should read full.
Test 3:
a. Plug the plastic connector back in.
b. Jumper the connectors on top of the fuel sender that correspond to the light green wire w/orange stripe and the black ground.
c. The low fuel light should turn on.

If any of the three tests gave you an unexpected result, you may have a problem related to the fuel gauge or wiring etc. However, if all tests “passed”, your fuel gauge is good and the problem is most likely the fuel sender.

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This is a great guide. I wish I'd had this handy when I did my dashboard LED conversion too, as it would have made it a lot easier to test the functionality of the low fuel light :)

Old school pilot here. The one gauge we Never trust is the fuel gauge. I have had Mustangs, Vettes, you name it and never paid them any attention. Most read full for days and began moving and once they hit 1/2 way took a sudden dive towards E.
I simply reset my trip meter on filling and also reset my GPS. At 200 miles find the station of choice and fill up.
Repeat. Unless that wonky gauge really bothers you consider it a trait of the D and also most cars.
Even my new Mustang Gt's gauge is a joke with the computer readout counting down single digits in miles to go only to still have 75 miles to go.