Fuel Gauge - Adjustment

[Doug]

My fuel gauge and sender function properly and dependably. � However the gauge will never read quite full but more like 3/4 full when the tank is topped off. �Is there an adjustment on the reproduction fuel gauges to fine tune the reading for full? �If so, how to you adjust it.

[bayo500]

I bent the float arm down on mine, it read 3/4 when it was full, I carefully bent it slighty in the middle so I did'nt damage the the rheostat (wires)

[Matto]

I read a thread on the 2A site where they mention an adjusting screw which is accessed thru a small hole in the back of the gauge. I have what looks to be an original gauge and there is no hole or adjusting screw on the back. Maybe the repro gauges have one? The Vernco site has a very good description of fuel gauge calibration at the following site.
http://www.vernco.com/sparks/id697.htm
There is also a good description of how to take a gauge apart and repair it on the 3B site.
Matt

[Carls_jeep]

I have a fuel gauge of unknown brand and a fuel sender of unknown brand. Mine was empty and showed 1/4 tank and full was past the full mark. The trouble was it would stop at 1/4 tank and still run for quite a while. I did not like that.

I adjusted the float arm until it just touched the bottom of the tank so now when it shows empty there is two gallons in the tank. When the tank is full it shows just past 1/2 tank and at at 1/4 tank I have 5 gallons left.

Now at least I know how much gas I have when I look at the gauge. I had to put a resistor in the line to regulate the voltage to the gauge to get it to show empty when the tank was empty. Then when I added gas the needle began to move when I had 2 gallons in it.

Now I know when it shows empty I can drive about 30 miles and that is all.

[Doug]

If I short the sender unit wire to ground, thereby bypassing the sending unit, that would tell me whether the sending unit arm required bending, correct.  In other words, if the sending unit is shorted to ground and it still reads 3/4, then the adjustment would have to be in the dash gauge correct?

[Doug]

I shorted the sending unit to ground and it made no change.  So I am assuming the sending unit at full is already doing its job and grounding the dash gauge out.   I reached around the dash gauge and there is a hole in the back of the gauge about the size of a pencil.  Now what to put in the back of the gauge to adjust it with, straight or phillips head?

[Doug]

So I just snapped this photo.  There appears to be a slot for a small screwdriver, like you would use to repair glasses with.  Does anyone know if it is supposed to be used to adjust the gauge.  I hate to turn it only to find out that I was not supposed to.

[Matto]

Halfway down this page http://www.thecj2apage.com/forums/the-neverending-gas-gauge-dilemma_topic12752.html they talk about adjusting the gauge with a jewlers screw driver. I took the bezal off my gauge and found no adjustment inside. It's a 6 volt gauge that I will not be using. So I'm interested to see how you make out with your replacement.

[aboyandhisdog]

Hey Doug and others,
I'm wondering if you ever got to the bottom of this fuel gauge problem? �Mine does the same thing - only reads 3/4 when filled up all the way. �The odd thing is that when I pull the sender out of the tank and run the float by hand, it works and shows "full" beautifully. �Very strange - why would it work fine (and read accurately) out of the tank but not when mounted in the tank? �As best I can tell, nothing in the tank is hindering the operation of the float arm. � Thanks!

[Doug]

Well you would have to ask how it went. � I tried to adjust the gauge while the gauge was still in the dash by reaching under the dash. � That was a mistake. It was nearly impossible to get the screwdriver in the tiny slot. You definitely need one of those little screw drivers that work on sunglasses or on jewelry.� After poking around in the gauge for 15 minutes, it went from working perfectly (accept for the not reading quite full) to only reading 1/4 full. �(I was concerned that I might ruin the gauge poking around in it without removing the gauge, but part of what I hoped to determine was whether the gauges could be adjusted after installed without removing. �However since I was working with a $16.00 repro gauge, I did not have too much to risk.) �So I removed the gauge from the dash to access it better. � �I then found that the gauge definitely is made be to adjustable. �However, I found that the adjustment mechanism was inconsistent at best. � I found that when I was turning the little dial that I got very consistent adjustment results between empty and 1/2 full with the dial moving proportionate to the amount I turned the adjuster. �However, above 1/2 full, I found that only little tiny fractional turns on the adjuster would make the needle swing wildly. �It would either way past full or down past 1/2 full. �I never could get it to adjust properly.

I am not sure if the inconsistent adjustment characteristic above 1/2 full was because I damaged the gauge poking around in it earlier in the day or if it was like that all along. � They are very cheaply made and not very durable appearing inside. � I ended up buying a replacement repro gauge for $20.00 �to replace my old repro gauge. � When I installed the new repro gauge, it did not register full correctly either when first installed. �I tried adjusting the new gauge and found it much easier to adjust and more consistent. �Now with the new gauge, I have it properly adjusted and reading correctly. � �One problem with the new gauge, the construction is slightly diferent from my old repro gauge and if you look closely, you can tell there is a difference. �The old repro gauge had a white inside of the casing visible between the glass and the face of the dial. �so you would see black case, white inside case, and then then the black face. �The new gauge actually looks better appearing all black on the inside. � But it is different from my 3 other small repro gauges. �


I hope that long explanation helps. �If nothing else than to share my experience. �I think I did determine that the only way to really adjust them is to wire them and do all the adjusting with the gauge out of the dash. � Then disconnect the wires and install permanemtnly after all adjustments were complete. �But the repro gauges are made with an adjuster mechanism and if you are very delicate with the gauge, you can do some adjusting.  This was true for the $20 repro gauges.  I am not sure if the expensive repro gauges which are supposed to be eacctly like original gauges have an adjustment mechanism.