Gas Guage - Team Camaro Tech
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post #1 of 9 (permalink) Old Jan 20th, 13, 06:23 PM Thread Starter
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Robin
 
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Gas Guage

I have a 69 with guages on the console. When my gas guage nears the empty mark, the fuel warning light comes on. When the guage gets to empty, there is still about 8-10 gallons of fuel left in the 18 gallon tank. Of course, this sends me to the gas station a lot. What would be the solution to making it more accurate; possibly read empty when there are about 3 or 4 gallons left?

1969 SS 396/375
11C Norwood
M21 3.73 12 bolt

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post #2 of 9 (permalink) Old Jan 20th, 13, 07:13 PM
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Re: Gas Guage

The original equipment warning lights were coded to a common set-point at 20 Ohm's or a 1/4 tank. Some other GM modules go off at 11 or 1/8 of a tank.

Many of the reproduction units are said to trigger at approximately 50 Ohm's. When yours lights up take a Ohm's reading at the sender wire you will need that number.

To fix you can either try another aftermarket unit and see if it is better, or visit Radio Shack and add a resistor to your current Ohm's reading to bring it to 20 or so for 1/4 tank or down to 11 for 1/8 th. Basically take your reading, subtract the reading you want (20 or 11) and buy resistors of the difference, then add them tot he sender wire ON THE MODULE not the gauge.

The only other option is to install a variable set-point unit. M & H electric make one that is highly rated . Search for replacement "adjustable" low fuel warning module on their website.


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post #3 of 9 (permalink) Old Jan 20th, 13, 08:15 PM
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Al
 
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Re: Gas Guage

Sounds like the gauge or the sender is the problem, not the low fuel module. When the gauge says "E" take an ohm reading on the brown wire. Do the same when it's full. Should be 90 ohms full and 0 ohms empty. This should get you started in the right direction


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post #4 of 9 (permalink) Old Jan 21st, 13, 05:22 AM Thread Starter
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Re: Gas Guage

I will get some readings when the guage gets to E. It may be several days or so before I can run all the gas out that I have in it now, but I will repost after I get the guage to E. Thanks.

1969 SS 396/375
11C Norwood
M21 3.73 12 bolt

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post #5 of 9 (permalink) Old Jan 21st, 13, 05:30 AM
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Re: Gas Guage

Just remember that the LFWM output is independent of the gauge reading not dependent on the fuel gauge reading. The sender would be the item at fault if both the gauge reading is wrong, and once you know what Ohm set-point your module has - if it is 20 or less - and it goes off at more then 1/4 tank.


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post #6 of 9 (permalink) Old Jan 23rd, 13, 07:20 PM Thread Starter
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Robin
 
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Re: Gas Guage

The warning light on the dash comes on when the guage registers E. Right now the guage is on empty (still plenty of gas left) and I believe that I have located the wire that comes from the sender. The thing is, I don't know what to connect the multimeter to besides the wire coming from the sender in the gas tank to read ohms.

1969 SS 396/375
11C Norwood
M21 3.73 12 bolt

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post #7 of 9 (permalink) Old Jan 23rd, 13, 08:17 PM
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Re: Gas Guage

Quote:
Originally Posted by rhcdmd View Post
The warning light on the dash comes on when the guage registers E. Right now the guage is on empty (still plenty of gas left) and I believe that I have located the wire that comes from the sender. The thing is, I don't know what to connect the multimeter to besides the wire coming from the sender in the gas tank to read ohms.
Follow this troubleshooter I wrote a while back...

https://www.camaros.net/forums/showpo...91&postcount=2

Post your results


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post #8 of 9 (permalink) Old Jan 27th, 13, 10:57 AM Thread Starter
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Robin
 
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Re: Gas Guage

OK, Brian. Here's what I have. I am pretty sure that I have somewhere around 8 gallons in the tank. The guage reads E and the warning light comes on when the guage reached E. With the sender leand disconnected, the needle goes past Full. With the harness grounded back to the guage, it reads just below E; just barely below E and almost touching the E line. I'm pretty sure the ground is good. I cleaned the ground and also used a temporary ground, then reconnected everything. Guage reads E. I tested the ohms. I got 0 ohms even though there is gas in the tank. I hope this gives you enough information to make a suggestion or diagnosis. Been staring at E too long. Gotta go get some fossil fuel.

New info: When I filled up the needle on the guage goes right up to the F line and just touches it. It does not go past full. I get 50 ohms with the tank full.

1969 SS 396/375
11C Norwood
M21 3.73 12 bolt

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Last edited by rhcdmd; Jan 27th, 13 at 01:31 PM.
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post #9 of 9 (permalink) Old Jan 27th, 13, 09:22 PM
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Re: Gas Guage

Yes you have confirmed that your sender is working but maybe faulty.
It should be putting out 90 not 50 and at 8 gallon should be sending more then zero.
Are you running a factory original gauge? If yes the back should have a hand wound wire resistor card mounted between the terminals. If the wire is broken the gauge will be off, but your test leads to a defective sender.


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