Gas Gauge Failure. . .How to fix...Thank you, Brian (69 Pace) - Page 2 - Team Camaro Tech
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post #16 of 103 (permalink) Old Jun 12th, 13, 06:45 AM
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Re: Gas Gauge Failure. . .How to fix...Thank you, Brian (69 Pace)

I am having the same problem on my 67 with console gauge. Went back to trunk and unplugged the sender. Grounded the wire to the gauge at the trunk plug got empty on the gauge. With the wire unplugged in the trunk I get full. Put a 40 ohm resister on the wire in the trunk got little under 1/2 on the gauge. Put a 10 ohm resister on the wire in the trunk got almost empty. I have to assume its the sender. Stuck a dowel rod down the fill port by my license plate but could not seam to find the sending unit with the dowel rod to see if it was stuck. Do you have to remove the fill neck in the trunk to use the dowel?
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post #17 of 103 (permalink) Old Jun 12th, 13, 07:13 AM
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Re: Gas Gauge Failure. . .How to fix...Thank you, Brian (69 Pace)

John - The 69 it is a straight shot to see the float from the filler neck. 67-68 it is not easy if at all possible to manipulate the float from the filler neck. I think others have accomplished that but don't know if dis-assembly was required.

But I think at this point the next test would be to connect an alligator clip test lead, or create a long test lead and connect one end to your sender's ground wire connection at the strap and shunt the other end to a known good ground, or the trunk latch and see if the gauge comes alive. If not I would be feeling confident if I drained and dropped the tank it would not be a waste of time. The sender does seem to the the issue - but it might just be the ground. If not you can remove the sender and bench test it.


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post #18 of 103 (permalink) Old Jun 12th, 13, 07:27 AM
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Re: Gas Gauge Failure. . .How to fix...Thank you, Brian (69 Pace)

Brian
Good advice!
I forgot to say I did run a wire from the tank ground wire to another ground location with no change. I also forgot to say that when I unplug the trunk plug to the sender and measure resistance to ground it is always 90 ohms or so. I used my ohm meter on the sender while trying to get at the sender with the dowel. Figured if I touched the sender with the dowel that I should see a change in ohms on my meter. No luck there!
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post #19 of 103 (permalink) Old Jun 18th, 13, 07:17 PM
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Re: Gas Gauge Failure. . .How to fix...Thank you, Brian (69 Pace)

Guys, I have a similar problem with my 69 with console gauges. Using the troubleshooting guide noted here (along with some good advice) it looks like it is my sending unit because I get about 135 ohms at the trunk connection; the tan wire.

The question I have now is: what would cause the gauge to go past full when I turn off the ignition? Based on the troubleshooting, that would lead me to believe that the tan wire is grounding out somewhere between the lead in the trunk back to the sending unit.

Am I way off here? I am waiting on a new sending unit to arrive and to use up the gas so I can drop the tank, I suppose that when I do that, I'll be able to tell if the tan wire is in good shape.

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post #20 of 103 (permalink) Old Jun 18th, 13, 07:30 PM
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Re: Gas Gauge Failure. . .How to fix...Thank you, Brian (69 Pace)

Bill,
Not sure I understand your problem but from my test 135 ohms would make your gauge go past full I think. Go to radio shack and buy a 10 ohm a 40 or 50 ohm and a 100 ohm and try them one at a time on the tan wire in the trunk. One end of the resistor needs to be grounded. If you get 1/8 tank on the 10 ohm 1/2 tank on the 50 ohm and full on the 100 ohm then its your sender.
I assume you tried to ground the tan lead and get empty.
I am thinking about making a box with a 3 position switch with the resistors in it. The box would just plug into the trunk plug and then this test would be easy.
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post #21 of 103 (permalink) Old Jun 18th, 13, 07:32 PM
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Re: Gas Gauge Failure. . .How to fix...Thank you, Brian (69 Pace)

Bill, if the tan wire was grounded, gauge would show empty.
Siphon out or use some fuel, then see where the needle points.
Reading 135 ohms means there is a good circuit from the tan wire through the s/unit to ground - extremely full tank.

As far as the needle going past full after ign turned off, gravity affecting the needle? It is on the right side of the gauge. If you have a half tank and park the Camaro on an embankment drvr side down, does the needle 'fall' to the drvr side?

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post #22 of 103 (permalink) Old Jun 18th, 13, 07:40 PM
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Re: Gas Gauge Failure. . .How to fix...Thank you, Brian (69 Pace)

Thanks John, I guess my question is, what would make the gauge creep past full when I shut off the car instead of going to E or just below E.

When I did the test as written in the sticky, disconnecting tan wire - gauge goes past full, then grounding the harness where the tan wire connects - gauge goes past empty, I got those results.

When I checked the ohms on the tan wire I got about 135, hence the assumption that the sending unit has failed. The fact that the gauge doesn't go to E or below E when there is no power, is driving me nuts.

Anyhow, thanks again for your time. Don't know what I'd do without these forums since I'm new to Camaros, I used to have a 66 Chevelle, am really familiar with the 67 Chevelle too, but the Camaro is a different beast.
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post #23 of 103 (permalink) Old Jun 18th, 13, 08:07 PM
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Re: Gas Gauge Failure. . .How to fix...Thank you, Brian (69 Pace)

Bill,
My 67 console gauge stays where it was after you turn the ign off. If its at 1/2 tank engine running then shut ign off it stays at 1/2 tank. I think that is how they work.
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post #24 of 103 (permalink) Old Jun 19th, 13, 08:12 AM
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Re: Gas Gauge Failure. . .How to fix...Thank you, Brian (69 Pace)

Again, many thanks John, hopefully the new sending unit will fix the remaining gremlin.
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post #25 of 103 (permalink) Old Jun 19th, 13, 08:31 AM
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Re: Gas Gauge Failure. . .How to fix...Thank you, Brian (69 Pace)

Bill,
I am going to have to drop my tank to fix mine also. Please let me know how big of job it is and what you would do different if anything.
Thanks
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post #26 of 103 (permalink) Old Jun 19th, 13, 09:53 AM
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Re: Gas Gauge Failure. . .How to fix...Thank you, Brian (69 Pace)

The biggest pain in dropping the tank is emptying it. The rest is okay, better with a second set of hands. I'm about to drop my own tank because the sender currently in the tank is missing the return line so the original owner just capped it at the rail with a couple clamps at either end of a section of rubber hose and a screw. Old school fix for sure. Of course my tank is almost full so I may wait until its empty before I replace the sender just to avoid the fuel storage issue.


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post #27 of 103 (permalink) Old Jul 29th, 13, 10:03 AM
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Re: Gas Gauge Failure. . .How to fix...Thank you, Brian (69 Pace)

I have a few questions.

On a 68 console gas gauge. When you turn off the key...should the needle fall all the way to empty?
What happens if you manually move the needle with your finger?

The reason I'm asking is I had a wiring disaster yesterday and now my gas gauge is working differently or not working at all. Plus the fuel light came on but I'm nowhere close to empty. It went off again though.

This is what brought this up:

"I had bad scare today. I was asked what my "batt" gauge reads and to be honest, I have never seen it move since I've owned the car. I decided to take apart the console and inspect the connections. Low and behold, didn't think to disconnect the battery. When I loosened up the nuts on the batt gauge I saw a spark. Then I saw a puff of smoke in the wiring harness. Holy crap! Quickly disconnected the battery and inspected the harness. Didn't see any damage. Rechecked all connections. Reconnected the battery cables. Turned the key and my batt gauge moved! In the neg before starting the car...in the pos after starting the car. Cool!

Now the bad news...all of the sudden I see a ton of smoke coming from the harness and the shifter light bulbs on. No NO NO!!! Run and disconnect the battery. Inspect the harness and the GND wire (from the shifter to the shifter lights and the sawtooth gauge pod) melted and actually caused the wire to break at one point. Oh my God...

Well after some severe depression, total fear and self-loathing... I cut the wrapping from the harness to inspect. It APPEARS that only the GND wire had any damage. All of the GND wire sheathing was melted. I cut out all GND wire and made up a new GND distribution modeled after the original. It's funny how the original was part of the harness but does not go thru the connector where all the other wiring does. Checked all connections again and then connected the battery. No smoke. Watched all the gauges move as before...including the BATT.

Then strangely...my FUEL light went on in the dash...but I'm not empty. I notice now my gas gauge stopped moving. Damn it. Any ideas?

This is why I stay away from electrical stuff."


Wondering if I damaged the gauge or the resistor.

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post #28 of 103 (permalink) Old Jul 29th, 13, 12:39 PM
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Re: Gas Gauge Failure. . .How to fix...Thank you, Brian (69 Pace)

Wow well you may have toasted a fusible link down wind.

It does sounds like the LFWM - Low Fuel Warning Module is toast since it reads line Ohms to trigger the light and unless your tank sender is sending below the trigger point you shouldn't see it. Test the Ohms from the fuel sender and post that value. The gauge should match. The original resisters were just thin wire wound around the carrier and the wire is very fragile these days. Broken wire will result in wrong reading on the gauge. But we will understand more once you post the ohms reading you are getting from the sender.

The needle doesn't always move around without power, gravity sometimes will pull it one way or the other. If you move the needle with you finger and the power is on the needle should return to the reported value from the sender signal.

Rule 23 always have a 1-2-3 dry extinguisher in the car.


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post #29 of 103 (permalink) Old Jul 29th, 13, 02:03 PM
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Re: Gas Gauge Failure. . .How to fix...Thank you, Brian (69 Pace)

Quote:
Originally Posted by 69-Pace View Post
Wow well you may have toasted a fusible link down wind.

It does sounds like the LFWM - Low Fuel Warning Module is toast since it reads line Ohms to trigger the light and unless your tank sender is sending below the trigger point you shouldn't see it. Test the Ohms from the fuel sender and post that value. The gauge should match. The original resisters were just thin wire wound around the carrier and the wire is very fragile these days. Broken wire will result in wrong reading on the gauge. But we will understand more once you post the ohms reading you are getting from the sender.

The needle doesn't always move around without power, gravity sometimes will pull it one way or the other. If you move the needle with you finger and the power is on the needle should return to the reported value from the sender signal.

Rule 23 always have a 1-2-3 dry extinguisher in the car.
Oh I have the extinguisher all right!

The fuseable link comment scares the hell out of me...anywhere I can check specifically? However, everything seems to be working, lights, radio, etc...car started up. Only the gas gauge is acting weird.

I'm thinking of picking up a resistor for the gauge...they're pretty cheap.

I'm also thinking of replacing the console harness with a reproduction to be safe. Thoughts?

I'll get back to you with the ohm measurement...Any direction on where that wire is in the trunk on a 68?

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post #30 of 103 (permalink) Old Jul 29th, 13, 02:31 PM
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Re: Gas Gauge Failure. . .How to fix...Thank you, Brian (69 Pace)

Quote:
Originally Posted by MMMM_ERT View Post
Oh I have the extinguisher all right!

The fuseable link comment scares the hell out of me...anywhere I can check specifically? However, everything seems to be working, lights, radio, etc...car started up. Only the gas gauge is acting weird.

I'm thinking of picking up a resistor for the gauge...they're pretty cheap.

I'm also thinking of replacing the console harness with a reproduction to be safe. Thoughts?

I'll get back to you with the ohm measurement...Any direction on where that wire is in the trunk on a 68?

Well I would test the existing resistor first - no point throwing money away

I like American Auto Wire factory fit harnesses. http://factoryfit.com

I think it is in the same place on a 68 as it is on a 69 in the trunk where the license plate light plugs in.

Fusable links that are often toast are the one at the hrn relay/main bus and the one by the battery junction block but it sounds like you are okay if all your accessories work and the car starts.


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