[165th]

The fuel gauge indicator on the survivor is buried past the F.

Here's some troubleshooting I've completed so far:

A. Checked to be sure the ground to rear tail panel is making a good connection. I did have to dremel with a sanding stone the tail panel and ground wire to improve the connection. Ohmed the ground wire. Check.

B. Checked to see if 12V is making it to the tip of the brown wire that plugs into the sensor. Check.

I read a few older posts and have gleaned that that it could be because the power is not getting to the sensor, but as mentioned, I do have 12V arriving at the tip of the brown wire.

Any other thoughts before I drop the tank and replace the sender? If I have to replace the sender who's sender is recommended.

Thanks.

[SS-TA]

Check the resistance across the sending unit, GM Fuel Gauges run 0-90 ohms (although in many cases a full tank can be as low as 60 ohms). If you get a reading higher than 90 ohms it is likely the sender is bad (they corrode over time).

[Held for Ransom]

http://www.forums.maxperformanceinc....d.php?t=593429

More than likely a sending unit issue. Try to find another used one if you can't repair yours.

[165th]

SS and HFR, thanks for this information. I just grounded the power wire going to the gauge, and it did swing the needle to E. Yay, and least this is narrowing things down to likely being the sending unit.

I have a used replacement sender ready to install.

For the replacement I tried just ohming from the power lead to the body of the sender. I'm getting readings, but nothing consistent. Numbers bounce all over the place. They change and generally go from 40 to 140 when you swing the float towards full, but the readings are terribly innacurate. Jumps between 20's to 140's as your swinging the arm. When holding steady I can't get the ohmmeter to settle down on any single output. Is that normal?

[superdutybob]

My guess is that the sending unit is rusted or corroded from sitting with little or no fuel in the tank. I would try one of the rust dissolvers that folks are using to de-rust the bottoms of cars. The stuff that NJSteve used on his white T/A. I was able to clean up the one in my 74 and made it work just fine.

[165th]

Thanks Bob, that's a great idea. I have some 'Safe Rust Remover' that NJSteve used. That product works great.

I'm going to pull the existing sender too, so I'll both on the bench to compare. Maybe between the two of them, I can get one to work properly.

[transam1972]

165TH...this is like deja-vu to me...when I got my car I had the exact same problem...I swapped the fuel gauge that I salvaged from my 1976...same problem..I pulled the sending unit and swapped it with my 70 Esprit and problem solved...fast forward to 2015..as I have not started the car in perhaps 15 years??...I recently pulled the tank and even though it had gas in it the sending unit was very rusty corroded and I feel a new tank is in order as opposed to salvaging the original (sometimes you gotta let go)...repop sending units are $63 from parts geek (you may not consider that)...I have a spare early FUEL gauge if you or anyone needs...but it is most likely the sending unit..I wish you success!...I should actually read everyones post as I see you are way ahead of me

[superdutybob]

Originally Posted by 165th

Thanks Bob, that's a great idea. I have some 'Safe Rust Remover' that NJSteve used. That product works great.

I'm going to pull the existing sender too, so I'll both on the bench to compare. Maybe between the two of them, I can get one to work properly.

Let us know how it works................with before and after pictures of course!

[Greg Reid]

Notice in the thread that HFR posted the link to that in Jay's case, the sending unit itself was not bad...Just corrosion at the ribbon connector ON the sending unit. Pay special attention to post #26 through the next page or so. There are photos of the problem area.
I'd check that and if you find that to be the case, I'd repair the original before replacing it with a new one.
I've heard some disturbing reports about the lack of longevity of the new ones. It's not one of those jobs you want to fool with on a regular basis...

[Held for Ransom]

Originally Posted by Greg Reid

Notice in the thread that HFR posted the link to that in Jay's case, the sending unit itself was not bad...Just corrosion at the ribbon connector ON the sending unit. Pay special attention to post #26 through the next page or so. There are photos of the problem area.
I'd check that and if you find that to be the case, I'd repair the original before replacing it with a new one.
I've heard some disturbing reports about the lack of longevity of the new ones. It's not one of those jobs you want to fool with on a regular basis...

Which is why I replied with "used" unit.

[165th]

Wow... well, I got just the right information here to bring the existing sending unit back to life.

All of these tips and troubleshooting steps were SO valuable. Thanks to you all.

Bob, I happened to have some Safest Rust Remover, so I worked the sending unit pretty good, but I think in my case, the copper pin was not well secured to the metal ribbon strap to sending unit. Noticing it was loose, I used a socket and tapped the keep down to tighten the assembly.

Here are some before and after pics. These forums just saved me from:
A. Having to remove the in dash fuel gauge and replace. $
B. Purchase a new 'bright' sending unit that would have stuck out like a sore line under the survivor. Yuk and $
C. Finding a new stamp on the tank that everyone will go crazy seeing, and eventually after millions of dollars of R&D will be available at ECS as a repro.... Priceless

[Greg Reid]

Well done....

[transam1972]

nice work!!..165TH your sending unit looks perfect and nice that you could keep the original..the one I just pulled looks like something that was salvaged from the TITANIC..I need to get a repop unit..it will be interesting to see how it compares to an original unit

[Greg Reid]

The one I got from Tamraz was the closest in appearance to the original...but this was for a '66 year model.
The one I bought for my '68...can't remember the manufacturer... I got it from Advance. So far so good....going on a couple of years.

[165th]

A picture is worth a thousand smiles....
First after reinstalling the tank with just a splash of fuel in it.
Second after adding 5 gallons.

[tdavidl]

so I just had the brakes worked and fixed, front & back were checked and fuel gauge is pegged past full like this thread...,the ground wire to the tail panel is fine, i'm wondering if someone dislodged a wire while under the car....anyone have a diagram of the wiring from the tank to the gauge ?

[Formulabruce]

Originally Posted by tdavidl

so I just had the brakes worked and fixed, front & back were checked and fuel gauge is pegged past full like this thread...,the ground wire to the tail panel is fine, i'm wondering if someone dislodged a wire while under the car....anyone have a diagram of the wiring from the tank to the gauge ?

Ground the wire + wire that goes to the tank, at connector inside the trunk. ( gauge side of it) Should get your fuel gauge back to zero,. This tests everything forward of the trunk.
The sending unit, just like temp sender for a gauge is a "gradual ground" This one works on a float and resistor, temp works on temperature operated resistor.
Next other end of same connector and check the resistance to ground. It is, most likely Infinite., Time to check that ground at inside of tail panel, middle of car First.
Then youll have to consider dropping the tank. Good luck!

[tdavidl]

Can I just ground the tan wire inside the trunk, gauge side ?

Sent from my XT1080 using Tapatalk

[Formulabruce]

Yes, power on, and ground the wire from up front with key on. Your Fuel gauge is a volt meter, and you are just grounding the ground side of it. This will eliminate everything from the rear of the trunk forward. Then check that small ground wire under the car on the inside of the tail panel. Good luck!

[tdavidl]

thx, will try next weekend when I can get a 2nd set of eyes on the gauge with key on when I ground it....also read needle can get stuck if pegged past full which it may be...which will really suck