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Old 01-31-2013, 08:30 PM
Spencerforhire Spencerforhire is offline
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Join Date: Dec 2012
Location: Jefferson City MO
Posts: 14
Default 1970 fuel gauge problem

I was wondering when you replace a gas tank and fuel sending unit do you have to replace the fuel gauge as well. I am replacing both units with the spectrum units. I have just heard of some problems with the fuel gauge not reading full after replacement on some other forums. Any info would be great.
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Old 01-31-2013, 08:39 PM
shadowgray396's Avatar
shadowgray396 shadowgray396 is offline
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Join Date: Dec 2009
Location: Tigard, Oregon
Posts: 6,000

First off Welcome to the site. I have been having the same problem with mine. Here a test you can do.

There are (2) wires that "disappear" on top of the tank to the sending unit. There is a black wire--the ground that needs a good sheet metal ground under the car, and a tan wire that sends the signal back to the dash.

You need to find where the tan wire unplugs from the rear trunk harness. Take the end that runs back into the car and ground it to a good ground. Have an assistant turn the key to "ON". The gauge should go to "E".

Now leave both ends of the Tan wire loose with the key in the "ON" position. The gauge should go way past "F".

If this checks out, the gauge is GOOD.

If this doesn't check out, it doesn't necessarily mean the gauge is bad, you could have an issue with the wiring between the sending unit and the dash.

Try this, need to disconnect the tan wire to the sending unit to check.

Do a Ohm check on the fuel sending unit with a digital multimeter set @ 200.

When the tank is empty it should read 2, at half full 40, and full 84-88 Ohms.
1970 SS Chevelle Van Nuys Built
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