Gas gauge 1/4 tank off
August 19th, 2018, 04:19 PM
#1
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Gas gauge 1/4 tank off
hello - I have a 70's cutlass supreme and my gas guage is off about a quarter of a tank.
My gas guage was very off so I removed the gauge from the dash console and saw some of the pins were bent so I removed the pins and re-soldered them and that helped however still about a 1/4 of a tank off.
I researched previous threads and saw one with the exact same issue but on that thread the guage was fixed once the pins were re-soldered which is not my case. Any idea as to what may be wrong?
Thanks in advance for your help.
My gas guage was very off so I removed the gauge from the dash console and saw some of the pins were bent so I removed the pins and re-soldered them and that helped however still about a 1/4 of a tank off.
I researched previous threads and saw one with the exact same issue but on that thread the guage was fixed once the pins were re-soldered which is not my case. Any idea as to what may be wrong?
Thanks in advance for your help.
August 19th, 2018, 08:31 PM
#2
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Explain further, does it ready 1/4 when it’s empty? Will it not read all the way full when the tank is full?
First things first, unplug the fuel tank sending wire, the gauge should go way beyond full. If so, ground the sender wire, it should read empty. If that checks out then mechanically and electrically the gauge can read correctly. That leave either a bad ground at the tank, a bad sending unit, or something preventing the sending unit float from moving in it’s intended range of travel. If the tank ground is good most likely the sending unit is bad.
First things first, unplug the fuel tank sending wire, the gauge should go way beyond full. If so, ground the sender wire, it should read empty. If that checks out then mechanically and electrically the gauge can read correctly. That leave either a bad ground at the tank, a bad sending unit, or something preventing the sending unit float from moving in it’s intended range of travel. If the tank ground is good most likely the sending unit is bad.
August 20th, 2018, 05:48 AM
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August 20th, 2018, 12:59 PM
#4
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Ok, let me retrace the steps.
The gauge does not show 1/4 empty, instead it's the opposite, it shows over 1/4 tank full. When I plugged the wire housing to the pins on the gauge the tank read it as all the way empty, then after turning the car on it reset itself going all the way past full, and I made sure the tank was filled prior to testing this to make sure the gauge would stop at the full mark. So a couple of questions from the input below, and please forgive my ignorance b/c I am truly still learning all the terminology.
Original comment:
First things first, unplug the fuel tank sending wire, the gauge should go way beyond full. (this mean I need to unplug the entire pin housing from the gauge, correct)
If so, ground the sender wire, it should read empty. If that checks out then mechanically and electrically the gauge can read correctly. That leave either a bad ground at the tank, a bad sending unit, or something preventing the sending unit float from moving in it’s intended range of travel. If the tank ground is good most likely the sending unit is bad. (How can I identify the tank ground wire for the fuel and where is the sending unit located and what does it look like it?)
Thanks.
The gauge does not show 1/4 empty, instead it's the opposite, it shows over 1/4 tank full. When I plugged the wire housing to the pins on the gauge the tank read it as all the way empty, then after turning the car on it reset itself going all the way past full, and I made sure the tank was filled prior to testing this to make sure the gauge would stop at the full mark. So a couple of questions from the input below, and please forgive my ignorance b/c I am truly still learning all the terminology.
Original comment:
First things first, unplug the fuel tank sending wire, the gauge should go way beyond full. (this mean I need to unplug the entire pin housing from the gauge, correct)
If so, ground the sender wire, it should read empty. If that checks out then mechanically and electrically the gauge can read correctly. That leave either a bad ground at the tank, a bad sending unit, or something preventing the sending unit float from moving in it’s intended range of travel. If the tank ground is good most likely the sending unit is bad. (How can I identify the tank ground wire for the fuel and where is the sending unit located and what does it look like it?)
Thanks.
August 20th, 2018, 03:46 PM
#6
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If you remove the wire from the sender and ground it with the key on it should go to E. If you just remove it from the sender then it should go way past F. If the gauge reads the same with the wire connected as it does with the wire off, it may be the sender.
Make sure your grounds at the gauge cluster are connected as this will cause gauge issues also.
Make sure your grounds at the gauge cluster are connected as this will cause gauge issues also.
August 21st, 2018, 05:56 AM
#7
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https://www.autozone.com/fuel-delive...48481_136244_0 Just installed one looks and works like the original.
Last edited by 2olds; August 21st, 2018 at 05:59 AM.
August 21st, 2018, 09:09 AM
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August 21st, 2018, 09:40 AM
#10
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As long as I've known my car (since '74 w/ ~23,000 miles on it), the fuel gauge has never been accurate. I've never owned an old "analog" car (pre-digitally-corrected stepper-motor-driven dashboard like most modern cars) that has had a fuel gauge that reads accurately throughout the range between F and E, there is always some amount of non-linearity between the sender and the gauge needle. On my car, after filling up the tank, you could drive 100 miles before the needle moved off the F mark, and as you consumed fuel (needle moving towards E), the faster it would get to E. The only thing that really matters is that, once it gets to E, that you NEED to stop and get some gas. Once it a while I let it get just a hair below E, and as long as I see the needle move occasionally as gas is sloshing around the tank, I know I'm not completely empty. When the needle stops moving, I know I'm "running on fumes" and I need to stop at the next nearest gas station.
More recently, I know my sender is getting intermittent and once in a while I'll see the needle way past F. But getting the fuel to slosh around a bit typically restores its function.
More recently, I know my sender is getting intermittent and once in a while I'll see the needle way past F. But getting the fuel to slosh around a bit typically restores its function.
August 21st, 2018, 10:16 AM
#11
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Find the sender wire in the trunk, I think it’s a tan wire? It drips thru a grommet in the trunk, near the trunk latch. There will also be a brown wire, that is the feed for your license plate light. If you ground the tan wire, and the gauge reads empty, and then reads way beyond full with the wire disconnected, you can be pretty sure the wiring from the sensor to the gauge is good. Next, check the ground wire to the sender. On my 69, the sender gauge is grounded to the body near the drivers front corner of the tank, on one of the trunk floor brace. Make sure the wire is in good shape, clean the ground point on the body, and the ground wire ring terminal. If all is good then it’s tome to drop the tank and look at the sender
August 21st, 2018, 03:56 PM
#12
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Had the same problem went pass full 1/4 and ran out gas at a 1/4 tank.The part where it sweeps on the sender wears out.New sender fix it.I got a new AC delco lasted 2 weeks float fell apart garbage.
August 23rd, 2018, 05:49 AM
#13
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Find the sender wire in the trunk, I think it’s a tan wire? It drips thru a grommet in the trunk, near the trunk latch. There will also be a brown wire, that is the feed for your license plate light. If you ground the tan wire, and the gauge reads empty, and then reads way beyond full with the wire disconnected, you can be pretty sure the wiring from the sensor to the gauge is good. Next, check the ground wire to the sender. On my 69, the sender gauge is grounded to the body near the drivers front corner of the tank, on one of the trunk floor brace. Make sure the wire is in good shape, clean the ground point on the body, and the ground wire ring terminal. If all is good then it’s tome to drop the tank and look at the sender
I checked the sender wire (attached picture), I disconnected the wire from the grommet and as explained by matt69olds the gauge went all the way past full so based on matt69olds the sender wire/connector is good. I cleaned the connector piece a much as I could considering the size of it and re-plugged it and the gauge went back to it's original setting so still a off. Could it be the pins on the gauge itself since I re-soldered them, maybe they are not 100% straight?
Another possibility mentioned by oldcutlass is to make sure the grounds at the gauge cluster are connected, to be clear the grounds mentioned here are the screws that connect the cluster to the dash, correct?
August 24th, 2018, 05:49 AM
#15
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Yes, missed that one. So I did ground the sender and the fuel gauge went all the way to empty then back to full. So you believe the issue may be with the sending unit itself inside the tank or is it possible some of the pins at the back of the gauge are not properly connected?
Thank you!
Thank you!
August 24th, 2018, 06:59 AM
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August 24th, 2018, 02:02 PM
#18
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