gas gage problems

[bob69]

The problem I'm having is my gage only reads about 1/2 full when I fill it up. But it does move down after a while & at about 1/8 full starts to be right. It's in a 69 with console & gages.Any one know where to look first Thanks Bob

[basecoupe#79]

Try this, in the trunk by the latch, you will see a connector with a brown wire. Disconnect the connector and turn on your ignition.  The gauge should go way past full.  If it does then gauge is good.  If not it may be a bad gauge, or bad grounds.  Bad grounds can cause you to pull your hair out.

With disconnected connector in the trunk, use an ohmmeter and check the resistance of the brown wire coming from the tank sending unit, to a good ground. Hopefully, it will measure between 0-90 ohms. If not, either the black wire screwed to ground at the tank is broke or not making a good ground, and or the sending unit is bad.

Also, check this company out.  http://www.fix-a-gauge.com/

This is a good cheap product to have in any Garage.

John

[bob69]

Thanks, I got a chance to try what you said, the gage went pass full & I cleaned the ground on the tank.The gage made some progress but still comes up short when full. So is it posabale I just have a bad ground some where else? Or is it the sending unit? Thanks Bob

[basecoupe#79]

Hard to say.  Do you have an ohm meter?  If yes, then empty tank as much as possible and pull it. This is a good time to look for your build sheet if you have not already found it.  Remove your sending unit.  This is a good time to check your fuel screen on the unit.  My screen was totally worn/rotted away.  I checked the sending unit by touching the leads of the meter to the connector on the unit and the other lead to the ground tab on the sending unit.  Move the sending unit's float from one extreme to the other.  It should go from zero to ninety Ohms.  If you get nothing or anything other than 0-90, then I would say the unit is bad.

John

[bob69]

Thanks John, I just filled it up so it's going to take a while to burn the gas up. But when I can I will pull the tank and check the sending unit. Bob