I put an autometer fuel guage in my 69, I just got it running the other day and the fuel guage worked fine.
Today, I noticed the guage has gone to way past full?
No matter what I do it stays there? :confused:
I checked and I have a good switched (+) and I also have a good ground.(at the guage)
I did a search on the subject and if I am reading correct, I should disconect the brown lead to the sending unit and put it to ground, this sould bring the meter to "o"? Or will it be full?
I know I have less than 1/2 tank, and I cant drive the car to fill it up as I dont have the front clip on it.
Are there any wires in the front harness that would cause this problem?
Could I have shorted the guage with a wire from the front harness?
All the other guages work fine as do the dash lites.
The only werd thing is the brake warning lite stays on untill I either push the "e" brake or start the car? But, I dont have the lead going to the brake distribution block plugged in, so that may be the problem there?
Anyway if I unplug the brown lead to the sender, I should be able to read ohm's between 0-90 on the sender side if it's working?
And then, if I ground the brown wire going towards the guage, the guage should move one way or the other?
I really dont want to remove the guage as it's a real pain, will the above method tell me if it's working properly?
I just cant figure why it worked when I put gas in it the other day, and now............? graemlins/clonk.gif
Any ideas will be greatly appreciated.
Thanks T.C.

TC, I am NOT an expert on this matter, so someone can correct me if I am wrong.

I do believe you are correct that the sender is a 0-90 ohms sending unit. With half a tank you should be reading 30-60 ohms across the leads, but I am not sure which leads until I look it up.

Also, double check that you have a good ground going to the car body. Use a brass brush to clean where the ground wires attach, and I like to use just a touch of dielectric grease (Dow Corning DC-4) on the back of the lead and the body where it attaches after I clean them both with a brass brush. It should help keep corrosion to a minimum and reduce any dissimilar metal galvanic action.

Do you have your interior in yet? I am fighting with the wife and daughter about colors and I want your colors of exterior and interior, they want a black interior.

Steve

Thanks for the reply Steve:
I have #4 (1" wide x 1/16" thick)groung straps body to frame/motor to body, all new and clean.
I have the ground from battery going to bare alum. head.
I checked the ground at the guage and it is good, as is the switched power wire.
Today I will check the tan wire, acording to the manual it's the fuel sending wire.
As you said I should get between 0 and 90 ohm's.
I have the fuel guage where the clock would be so I cant get to it very easy, I need a way to check it without taking the complete dash out.
Cause thats a pain!
Hopefully I can ground the sending wire going to the guage or put a resistor in line and the guage will move? (then I will know it's the sending unit)I think?
No I havent got the rest of the interior in yet,wish I did.
I went with the Parchment because "everybody does black" it's even cheeper to do black.
I really think the off white and blue will look really good.
The only other color I would consider is fawn or dawn? It's more of a light tan color, but I would have to see it before I decided.
T.C.

Looks like you have a handle on the gauge troubleshooting. So I just want to pass on some helpful info.

"I have the ground from battery going to bare alum. head."

You might want to move the ground cable to the block. The high current during starting can cause corrosion of aluminum parts, intake manifold or heads. The corrosion is not seen from the outside as it's usually the area where the aluminum contacts the engine cooling water.

Thanks for the reply Elree, I didnt think of that and I will move the ground to the block.
Today I called Autometer and was told to ground the guage as close to the sending unit as possable.
I did, and the guage did as he said it would proving the guage is good and the wire from the trunk to the guage is also good.
So that leaves the sending unit, I have allready checked the ground, so thats out.
That only leaves one wire.
Anyone know who has the best sending units?
Are the repo's any good?
Thanks T.C.