Fuel Gauge Inaccurate - Team Camaro Tech
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post #1 of 9 (permalink) Old Dec 3rd, 06, 04:34 AM Thread Starter
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Fuel Gauge Inaccurate

My center-dash fuel gauge keeps the needle at about the 9:00 position. It does move when adding fuel so it seems to be receiving a signal. I have a re-pop sending unit in the tank and new wiring throughout the car. The fuel gauge is an original GM unit and I believe the grounds are securely fastened.
I suspect the sending unit is faulty. What do you think?

Skunk Works
302DZ, M22W Muncie, GV overdrive,12-Bolt Rear 3.73
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post #2 of 9 (permalink) Old Dec 3rd, 06, 05:16 AM
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Re: Fuel Gauge Inaccurate

I think some testing is in order.
Disconnect the tan wire in the trunk, see if the guage needle goes past full. If it does, the guage and wiring are good.
Make sure the sender and license plate light wires didn't get reversed at that connector in the trunk.
Then replace the sender.





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post #3 of 9 (permalink) Old Dec 3rd, 06, 01:09 PM Thread Starter
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Re: Fuel Gauge Inaccurate

JimM's Testing 101 results: I disconnected the tan wire and the needle swings on around past full. This must mean the repo sending unit, that I paid ~$45 for, needs replacing. Why do they sell parts that they know are no good? Should I pay the $150 for a GM unit just to be sure the thing works?

Skunk Works
302DZ, M22W Muncie, GV overdrive,12-Bolt Rear 3.73
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post #4 of 9 (permalink) Old Dec 3rd, 06, 01:25 PM
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Re: Fuel Gauge Inaccurate

Quote:
Originally Posted by X33D80 View Post
JimM's Testing 101 results: I disconnected the tan wire and the needle swings on around past full. This must mean the repo sending unit, that I paid ~$45 for, needs replacing. Why do they sell parts that they know are no good? Should I pay the $150 for a GM unit just to be sure the thing works?


"most" of the repro senders work... could be something is hanging up the float maybe? Hard to say. Regardless, it has to come out.

Your license plate light works, right?





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post #5 of 9 (permalink) Old Dec 3rd, 06, 04:40 PM Thread Starter
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Re: Fuel Gauge Inaccurate

Perhaps I should fill the tank full and maybe it would jar it loose, but probably not. I have never had the tank more than 1/2 full. And if that didn't work, I would have 18 gallons of fuel to displace. Yes the tag light works. I am sure that the wires are not crossed.
Thanks for the help JimM.

Skunk Works
302DZ, M22W Muncie, GV overdrive,12-Bolt Rear 3.73
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post #6 of 9 (permalink) Old Dec 4th, 06, 10:37 AM
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Re: Fuel Gauge Inaccurate

Hey sweet ride X33D80, what kind of headers are you running?

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post #7 of 9 (permalink) Old Dec 4th, 06, 04:11 PM
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Re: Fuel Gauge Inaccurate

X33D80,

Are you sure the gauge is original GM? Read this little story...

On the 1969 I bought a few months back I had the fuel cell in the trunk taken out. That meant a new gas tank & sending unit. The odometer was messed up so I said ok a new odometer has to go in and while we are there lets replace the fue guage.

I get my car back and the fuel guage was mounted incorrectly by the factory which made it. Even though the car had a full tank the needle was around the 5 - 7 PM positions. If I were selling the car I would have said, the heck with it. But, since I bought it only a few months before, I took it upon myself to replace the brand new fuel guage with the old fuel guage that was removed...Ta Da, Presto Magico it worked. It was a defective guage. That's right the old one was fine, the new one was no good. I had an old 1979 Caprice Classic with a factory 350 in it that would do the same thing. The guage was bad. The seller told me that it was that way for years. Had he said I don't know I would have replaced the sending unit and been screwed. I just left it since it worked on most days.

Let me caution you though. I would stronly recommend removing the steering wheel or the front seat if you are a tall guy. Getting under the dash to replace the fuel guage is on a 1969 is no fun. Trust me, I just did it about 2 months ago. It $*cked.!! But at least the gauge works for now. Hard to believe but yes, the new fuel guage was bad. The old one was good.

P.S. Thanks to Jim for telling me which wires went where under the dash and in an unrelated matter the help with the washer pump. I bought both the fuel guage & washer pump at D&R classic. I kept the receipt and they took them back no problem. I buy almost all my stuff at D&R. I only wish I would have kept my old 1969. I hope that car is being well cared for. (Pre- X Code). By the way D&R Classic is awesome!!

P.P.S Now if I can only find the wire the prior owner(s) had cut going to the fuel guage idiot light. This thing under the dash still has issues. But thanks to eveyone here the car is in better shape than it was a few months ago.

Happy Monday!!

1) 1969 Camaro RS 396 TH 400, 12 bolt 3:73 sold 1994
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2) 1984 Z28, 5.0 H.O. T-Tops, G92 3:73, sold 1994
3) 1988 5.7L IROC-Z, sold 1994
4) 1969 Camaro bought 2006, back on the road in 2010
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Last edited by South Side Goons & Hitmen; Dec 4th, 06 at 04:14 PM. Reason: say, 4:10 in current car
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post #8 of 9 (permalink) Old Dec 4th, 06, 06:44 PM Thread Starter
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Re: Fuel Gauge Inaccurate

The rolling body I started with had no fuel tank or sending unit, so all that is new. The sending unit currently in the car is a reproduction, not a GM unit.
My comments were that perhaps I should buy a GM unit because I don't want to change it out and then still have the same problem. My confidence in the repop units is low. The center mounted fuel gauge is an original GM.
I will plan to remove the front seat if I have to start crawling around under the dash, but at this time the dash pad is not yet installed and I think I might be able to loosen the dash carrier and tilt it forward.
The headers are of unknown origin. They came with some other parts that I had bought and I had them ceramic coated by a local shop. They seem to be holding up OK thus far.
Thanks for the comments, suggestions, and conversation.

Skunk Works
302DZ, M22W Muncie, GV overdrive,12-Bolt Rear 3.73
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post #9 of 9 (permalink) Old Jan 1st, 07, 05:17 PM Thread Starter
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Re: Fuel Gauge Inaccurate

Using this info I reset my center dash gas-gauge reading: https://www.camaros.net/forums/showth...ge+calibration
With the tan sending unit wire unplugged the gauge read about 3/4 full and with the wiring harness connection grounded in the rear it read way below empty. An OHM meter test of the tan wire from the sending unit read 14.6. I knew that I only had a few gallons of fuel so 14.6 was probably pretty accurate.
So I removed the face from the gauge and with the rear tan wire unplugged I physically repositioned the needle to read just below empty. With the rear harness wire connected to ground it now swings to the far right. With it fully reconnected it now reads about 1/8 of a tank, which is probably pretty close.
I'll fill it up the next time I am out and see how it reads but I am optimistic that it will then read full. (I hope all this makes sense)

Skunk Works
302DZ, M22W Muncie, GV overdrive,12-Bolt Rear 3.73
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