gas gauge works great SOMETIMES?? - Team Camaro Tech
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post #1 of 13 (permalink) Old Aug 4th, 14, 03:32 PM Thread Starter
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gas gauge works great SOMETIMES??

gas gauge in dash works perfect one minute, next time i drive the car it is PEGGED out to the max right side?? maybe a ground issue? anyone have any ideas? i did locate the ground to frame coming from tank sending unit, and clean it up and re-mount to frame, with no results....anyone? thanks, Rick
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post #2 of 13 (permalink) Old Aug 4th, 14, 03:39 PM
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Re: gas gauge works great SOMETIMES??

Possibly the sending unit is bad.
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post #3 of 13 (permalink) Old Aug 4th, 14, 05:28 PM
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Re: gas gauge works great SOMETIMES??

When you located the ground to frame coming from tank sending unit, and cleaned it up and re-mount it to frame, how did the connection of the terminal look on the wire. This connection as well as others has to be good. The ground wire then goes up to a tab on the sending unit and it too is a crimped connection and there may be an issue there as well.

There is also another connector in the trunk that may also be poor.

If all of these are good, then chances are the tank will have to be dropped to further check things.

You could just as a temporary test to make sure things are good forward from the trunk, to and through the gauge, is to disconnect the sender wire in the trunk and securely ground the side of the wire that goes forward towards the gauge. The gauge should then be on empty or below. Now go out and drive it around and if it stays on empty then chances are even greater that the issue will require the tank to be dropped.

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post #4 of 13 (permalink) Old Aug 4th, 14, 07:43 PM
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Re: gas gauge works great SOMETIMES??

The troubleshooter here will help you isolate if it is wiring, sender or gauge. https://www.camaros.net/forums/showthread.php?t=195833

Let me know if you have any questions.


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post #5 of 13 (permalink) Old Aug 5th, 14, 04:10 AM
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Re: gas gauge works great SOMETIMES??

I recently had the same problem after replacing my gas tank with a spectra EFI tank. I thought it was the sender so I took everything apart and tested the sender and it checked out just fine. Doing the ground test by grounding the connector in the trunk and wiggling the wires in the trunk, I found that the gauge wire itself had an internal break. I replace the section if wire and all was fixed.

In the end I spent half a day taking the tank in and out when the real problem was a 47 year old wire that got pinched.
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post #6 of 13 (permalink) Old Aug 5th, 14, 06:23 AM
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Re: gas gauge works great SOMETIMES??

Also Rick, what year camaro?

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post #7 of 13 (permalink) Old Aug 5th, 14, 02:54 PM Thread Starter
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Re: gas gauge works great SOMETIMES??

this is a 1969 camaro.....gas gauge works great at times, but lately..(more times than not), it is just pegged out to the right way past full....i looked in trunk last night for a ground that might be coming off of sending unit, but didn't find anything in the trunk that didn't seem related to tailgihts, etc...???? what wire am i looking for in the trunk?

Torch, are you saying you had a bad wire at the gauge itself?? thanks for all the replies so far! I WILL FIND THIS SUCKER! LOL..Rick
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post #8 of 13 (permalink) Old Aug 5th, 14, 05:48 PM
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Re: gas gauge works great SOMETIMES??

My problem was the wire itself in the trunk where it went by the cocktail shaker.
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post #9 of 13 (permalink) Old Aug 6th, 14, 06:18 PM Thread Starter
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Re: gas gauge works great SOMETIMES??

Quote:
Originally Posted by 69-Pace View Post
The troubleshooter here will help you isolate if it is wiring, sender or gauge. https://www.camaros.net/forums/showthread.php?t=195833

Let me know if you have any questions.
69-Pace....thanks so much for this advice...i followed it step by step last night, and it worked out that my fuel sending unit has apparently lost it's will to live..LOL the test for the wiring and gauge forward went perfectly as described...checked the ground down by the tank strap, and even rigged a temp ground...NOTTA....then checked ohms (resistance on sending unit, and they didn't jive at all with an almost full tank...actually read in 10ths. SO, the question is what sending unit to go with, i have heard good and bad about some of the aftermarket units..do i cough up almost 200hund for original replacement??? any advice from ANYONE would be appreciated! thanks again...Rick
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post #10 of 13 (permalink) Old Aug 6th, 14, 06:59 PM
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Re: gas gauge works great SOMETIMES??

I had an original sender in my 74 years ago and it was bad, or so I thought, but I only tested between the top pin where the push on connector goes and the ground tab where the ground wire attached to. I was about to replace it but dug deeper and did more tests and found a problem and after I fixed it, the sender still works perfectly today.

The topside pin passes through an insulator and then sticks out on the underside of the assembly which would be inside the gas tank. This pin then has a flat strap on it with a hole in the middle of it on that end and when it was assembled it was held together with a push on clip. Lower on down this strap it is then inside of a plastic insulator and further down it then connects to the variable resistor can. On mine I showed no continuity between the topside of the pin and the flat strap. Turns out this pressure fit between the flat strap and the pin with the push on clip had corroded. I carefully cleaned the strap and the pin and was able to use my soldering gun to heat the joint and flow solder between the pin and flat strap thus allowing it to make a solid electrical connection. I tried removing the clip but it's made to go on one way and lock and would not have been easily removed.
After this I checked the sender again and it worked as originally designed. So far after 15+ years this repair has held up just fine.

If you do get a new sender, check and recheck it to make sure it's working before you put the unit in the tank and fill the tank with fuel. I've heard of poor quality control on some out there.

Jim

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post #11 of 13 (permalink) Old Aug 6th, 14, 10:32 PM
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Re: gas gauge works great SOMETIMES??

For the most part GM's are out there new and NOS. The reproductions for the two line are fairly reliable these days and affordable.

I strongly recommend before installing the new unit in the tank that you hook it up and test lead ground it and see what Ohm's it is putting out and see how fast the gauge responds.


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post #12 of 13 (permalink) Old Aug 7th, 14, 01:20 AM Thread Starter
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Re: gas gauge works great SOMETIMES??

well, my original engine 350 only has a one line fuel sending unit...are you saying that the reproductions are not reliable for this application? when i get the new unit, what is the exact procedure to test it? can it be done without hooking it up to gauge? (before i drop the tank, etc) thanks guys!
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post #13 of 13 (permalink) Old Aug 7th, 14, 04:24 AM
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Re: gas gauge works great SOMETIMES??

No but I only have personal experience with the dual line senders out there recently. As anything these days avoid the lowest price grey box unit you find on offer. I bought mine through Ricks if I remember right.


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