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How to make autometer fuel gauge read properly

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what about using a 90 empty / 0 full gauge like this one http://www.summitrac...rts/VDO-301107/ it wouldn't read Full precisely, but empty would be on point.

 

i presume that since its an american product, you would have the same problem; it will have a similar behavior to the autometer gauges.

 

has no one duplicated this thread's procedure? what about the author? perhaps he can confirm/deny the actual installed behavior.

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has no one duplicated this thread's procedure? what about the author? perhaps he can confirm/deny the actual installed behavior.

 

I have tried to duplicate most of the suggestions in this thread on my ’71 240Z, which until recently, had a stock tank/sender and the Ford-spec Autometer gauge.

 

I was unable to reproduce the results others have gotten building the resistor bridge using either their calculated or experimentally found recommended resistor values. I was finally able to get the gauge to read full and empty properly, but my resistor values were unique.

 

I did figure out why this was, and in a word, it is grounding. Take a look at these posts for a technical explanation (fair warning, they are long and dense, skip them if you are not up for it):

 

Star Grounding Scroll to Post #15

 

Grounding Scroll to Post #15

 

The fix was to run a new pair of wires from the gauge to the sender, one for signal, and one for ground. This removed the unique resistance the chassis ground scheme was adding to the resistor bridge, allowing me to reach a stable calibration. I also connected the gauge ground to the underdash ground buss from my star ground.

 

However, this does not really give you an acceptable solution. The combination of the stock sender and the Autometer gauge is so non-linear as to make reasonable calibration impossible (see post #20, above).

 

So, I got a bigger hammer:

 

http://forums.hybridz.org/index.php/topic/96955-a-%e2%80%9cstock%e2%80%9d-fuel-tank-solution/

 

This is still a work in progress, but the combination of the Autometer sender and Autometer gauge is nice and linear. I expect I will be able to get this combination to work correctly in one of two ways. I will post the results in the above thread when I get there.

Edited by Oddjob

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well I am bringing this back from the dead as I am just about to buy all of my gauges and found this.

 

http://www.summitracing.com/parts/ATM-2642/

 

a 73 empty 10full

 

pretty damn close to the stock Z, so I'll be going with this. no modification and it should just read off when max full. And really all that matters is when it is getting close to empty.

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well I am bringing this back from the dead as I am just about to buy all of my gauges and found this.

 

http://www.summitrac...parts/ATM-2642/

 

a 73 empty 10full

 

pretty damn close to the stock Z, so I'll be going with this. no modification and it should just read off when max full. And really all that matters is when it is getting close to empty.

 

If my memory serves, this is the gauge I went with (different face, same guts). I still used a resistor in parallel to slightly shift the readings. As far as getting close to empty goes, the gauge will get down to a certain point and never get lower. For my car, this is at 1/4 tank.

 

Not knowing when I'm about to run out of gas, and always keeping the car fairly empty for autocross renders the gauge completely cosmetic.

 

Did you have similar results?

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Bump.

 

 

 

The fix was to run a new pair of wires from the gauge to the sender, one for signal, and one for ground. This removed the unique resistance the chassis ground scheme was adding to the resistor bridge, allowing me to reach a stable calibration. I also connected the gauge ground to the underdash ground buss from my star ground.

 

However, this does not really give you an acceptable solution. The combination of the stock sender and the Autometer gauge is so non-linear as to make reasonable calibration impossible (see post #20, above).

 

Glad to see that all of my hard work wasn't out too lunch and that someone else has had the same experience / reached the same conclusions as I have.

 

 

 

Mine works perfectly (author). I am switching gauges since I got a chevy tank though.

 

I'm still curious as to why your experience was different than ours. You don't happen to have the exact model of your gauge, do you? I'd like to call AutoMeter and see if the guts are identical...

 

 

 

Anyone else out there attempt this install? Which result did you have? (Gauge model numbers would be helpful!) I'd really like to get to the bottom of this...

Edited by zredbaron

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what about using a 90 empty / 0 full gauge like this one http://www.summitracing.com/parts/VDO-301107/ it wouldn't read Full precisely, but empty would be on point.

 

Is this true? I have the autometer sportcomp that I plan on hooking up very soon and would like some insight. Has anyone gotten their autometer fuel gauges to read accurately? Im more concerned about empty being accurate. I was planning on adding a 5ohm resistor to ground to help the full level a bit but I realize it will affect empty as well. Is this correct as well?

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I have a small tip that i use when determining required resistance for setting LED brightness. Use a potentiometer instead of a resistor in your circuit when you are mocking it up. The pot will allow you to dial in the resistance to whatever you need, when it works just pull the pot and do a resistance test on its points, then buy a resistor that matches the value you find. Make sure you use a linear, and not logarithmic pot for best results.

Edited by Kurbycar32

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