Center fuel gauge will not read above 1/4 tank. Any suggestions? - Team Camaro Tech
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post #1 of 7 (permalink) Old Feb 21st, 09, 02:35 AM Thread Starter
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Chris
 
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Center fuel gauge will not read above 1/4 tank. Any suggestions?

Hi, thanks for reading my post - here is what I've got. 1969 Camaro with a autometer fuel gauge between the speedometer and tachometer. I'm trying to install a factory center fuel gauge from Rick's Camaros and I can't get it to read above 1/4 tank. I've read through the posts here and have tried the following with no results.

Check the gauge:
Disconnect the sending unit wire, the gauge goes to full. Ground it and the gauge goes to empty.

Check the sending unit ground:
Cleaned the ground connection for the sending unit near the mounting strap. Fill the gas tank, still reads 1/4 tank.

Check the sending unit (repro):
Drain and dropped the tank. It has a good ground connection to the sending unit body. I pulled the sending unit out of the gas tank and did some bench testing.

1) First test with my autometer fuel gauge, I was able to get a correct reading (empty to full) when I moved the lever up and down.

2) Hooked sending unit up an OHM meter and got correct 0-90 OHM reading.

3) I hooked up my new center fuel gauge, still get 1/4 tank when I move the lever to full position.

Bought a new Spectra Premium Sending Unit:
Thought my repro sending unit might not work with the OEM center fuel gauge. So I ordered a SPI sending unit and did the tests above. Same results, only 1/4 tank reading.

Resistor on the back of the gauge:
Put a new resistor on the back of the gauge (from Rick's Camaros). Bench tested, same result - 1/4 tank.

Check the gauge again - with a potentiometer:
This result is kinda weird. I hooked the pot. up to the gauge, the gauge will sweep from empty to full between the 0 - 10 OHMs (according to my OHM meter). The gauge will not respond between 10-90 OHMs when I turn the pot.

Do you guys have any further suggestions? I suspect it might be the gauge with the weird reading I am getting from the potentiometer.


Thanks!
1969 X-22 SS 396
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post #2 of 7 (permalink) Old Feb 21st, 09, 12:04 PM
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Re: Center fuel gauge will not read above 1/4 tank. Any suggestions?

I would suspect it to be the guage. You tried 2 different sending units with the same result.

Mike
69 Camaro Prostreet - purple w/ghost flames , 502 w/ 871 blower


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post #3 of 7 (permalink) Old Feb 21st, 09, 02:11 PM
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Re: Center fuel gauge will not read above 1/4 tank. Any suggestions?

I tend to think gauge aswell but recently i been through same dilema with my other car ( 69 vette)
after changing eveything once and still had same problem I grounded the case of the gauge and it works fine now.
(being on a vette might be different but ya never know)


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post #4 of 7 (permalink) Old Feb 21st, 09, 11:01 PM Thread Starter
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Re: Center fuel gauge will not read above 1/4 tank. Any suggestions?

dawg - How did you ground the case? Is is just a matter of soldering a wire to the case and then finding a good ground spot. Thanks
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post #5 of 7 (permalink) Old Feb 22nd, 09, 05:51 AM
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Re: Center fuel gauge will not read above 1/4 tank. Any suggestions?

mine had a small hole in the case and a 10-24 screw fit perfectly.


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post #6 of 7 (permalink) Old Feb 22nd, 09, 11:35 PM Thread Starter
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Chris
 
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Re: Center fuel gauge will not read above 1/4 tank. Any suggestions?

Quote:
Originally Posted by dawg View Post
mine had a small hole in the case and a 10-24 screw fit perfectly.
Yep, that was it! I ran a second ground to the gauge and now it will sweep empty to full when i bench test it. Now i just have to put it all back in the car.

Thanks SO much for the tip - I have been stuck on this problem for quite sometime

Chris
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post #7 of 7 (permalink) Old Feb 23rd, 09, 03:10 PM
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Re: Center fuel gauge will not read above 1/4 tank. Any suggestions?

np ANYTIME


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