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Old 04-19-2018, 01:01 AM   #126
TBONE1964
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Re: 67-72 Chevy Truck fuel gauge diagnostics 101

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Originally Posted by Shotgunn View Post
I guess Iím being ignored
Not ignoring you, just very busy and way behind.

Based on your diagnostics and what I can tell by reading your post, I would try a new gauge. Remember some new aftermarket gauges do not require a external resistor to work.

Hope this helps,
Tom
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Old 04-19-2018, 12:52 PM   #127
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Re: 67-72 Chevy Truck fuel gauge diagnostics 101

You may need a new gauge, but before doing that, I would test the gauge itself. Here's what I use for testing a 90 ohm fuel gauge.
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Old 04-19-2018, 05:36 PM   #128
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Re: 67-72 Chevy Truck fuel gauge diagnostics 101

Thank you both for responding.
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Old 04-23-2018, 09:31 PM   #129
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Re: 67-72 Chevy Truck fuel gauge diagnostics 101

Trying to finish a blazer tank swap on a truck I just bought. They left the tank swap about halfway done. My sending unit has the ground wire coming off it (I attached the other end of that to a tank bolt). I don’t have a wire connected to the center post/bolt on the sending unit. What wire should I be looking for? Tan wire that would have ran to the tank behind seat??

I haven’t looked yet, hopefully it’s just back there and I can add some wire to it to extend to the back.
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Old 04-23-2018, 11:12 PM   #130
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Re: 67-72 Chevy Truck fuel gauge diagnostics 101

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Originally Posted by hotwls13 View Post
Trying to finish a blazer tank swap on a truck I just bought. They left the tank swap about halfway done. My sending unit has the ground wire coming off it (I attached the other end of that to a tank bolt). I donít have a wire connected to the center post/bolt on the sending unit. What wire should I be looking for? Tan wire that would have ran to the tank behind seat??

I havenít looked yet, hopefully itís just back there and I can add some wire to it to extend to the back.

Yes it will be the same tan wire and you can extend it or just run a new wire. It runs from a location on the fuse panel named "FUEL GA"
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Old 04-23-2018, 11:21 PM   #131
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Re: 67-72 Chevy Truck fuel gauge diagnostics 101

The wire from the tank sending unit terminal goes to the FUEL terminal on the fuse panel. It is located on the middle terminal on the end of the panel.

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It's on the right end center terminal of this panel. This is just a connector for the sender wire to the fuel gauge which exits out the rear of the fuse panel and goes to the dash cluster plug to pin 4.

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Old 08-20-2018, 11:11 PM   #132
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Re: 67-72 Chevy Truck fuel gauge diagnostics 101

My fuel gauge doesn't move and it is below the empty mark. I pulled the resistor from the back of the fuel gauge and it doesn't give any readings with the multi-meter. I also checked the printed circuit and it looks like it is in pretty good shape. Would the resistor cause the gauge to not move at all? Could the fuel gauge just not be receiving voltage? The rest of the lights in the instrument panel work but the brake light only lights up when the engine is starting. The fuel gauge doesn't move though.

Any help would be greatly appreciated.
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Old 08-26-2018, 04:30 PM   #133
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Re: 67-72 Chevy Truck fuel gauge diagnostics 101

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My fuel gauge doesn't move and it is below the empty mark. I pulled the resistor from the back of the fuel gauge and it doesn't give any readings with the multi-meter. I also checked the printed circuit and it looks like it is in pretty good shape. Would the resistor cause the gauge to not move at all? Could the fuel gauge just not be receiving voltage? The rest of the lights in the instrument panel work but the brake light only lights up when the engine is starting. The fuel gauge doesn't move though.

Any help would be greatly appreciated.
Typically if the circuit board is good and the wiring to the circuit board, the temp gauge will work. The #3 wire on the cluster connector is a pink wire that feed battery voltage to the temp and fuel gauge. The power splits in the circuit board. If you have a good working temp gauge then your power is good up to the connector.

I would take a good look at the back of the circuit board and make sure the path for power is not burnt. You can use a test light and check for power right at the gauge itself.

The resistor should show some resistance. You should get around 85/90 ohms from a good working resistor. If not, replace it and see what happens.

Hope this helps,

Let me know,
Tom
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Old 08-29-2018, 01:53 PM   #134
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Re: 67-72 Chevy Truck fuel gauge diagnostics 101

Glad I stumbled into this thread- my fuel gauge (previously working great) just went to full 3 O'clock and won't budge. Last night I started simple- pulling the tan wire from the sending unit- noticed as I moved it up or down on the sending unit post the fuel gauge bounced to just below 'F' and then back to 2-3 O'clock.

Appears my tank is grounded to frame.

Might try a jumper ground wire from sending unit to frame- see what happens.

Great thread, btw- appreciate the information very much.
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Old 08-30-2018, 10:51 AM   #135
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Re: 67-72 Chevy Truck fuel gauge diagnostics 101

Does anyone know where you can get replacement resistors for the back of the fuel gauge?
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Old 10-05-2018, 02:24 AM   #136
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Re: 67-72 Chevy Truck fuel gauge diagnostics 101

I also would like to know where I can get the resistor needed for the gas gauge. Thank you in advance
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Old 10-05-2018, 10:00 AM   #137
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Re: 67-72 Chevy Truck fuel gauge diagnostics 101

http://www.truckandcarshop.com/

The online catalog is a little slow but its in there. TBONE1964 hooked me up with this site.

I replaced mine and my fuel gauge started working again. Before I replaced the resistor, the gauge was way below empty and didn't move. It was a much easier option than pulling the sending unit to check it out.
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Old 10-05-2018, 10:31 AM   #138
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Re: 67-72 Chevy Truck fuel gauge diagnostics 101

Thank you heyfish. The part number at truckandcarshop is 67-04508.
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