anybody ever had to re-calibrate your fuel guage?

[BUXMAN66]

having my dash problems (guages) sorted out from the guy i got my tach dash from (a board member). and one of the problems i was having involved my fuel guage.took out my old dash set-up and the fuel guage was still showing the last reading of the fuel tank which was 3/8 of a tank.i have not added any fuel nor have i ran it out,so it still should be at 3/8. got my new dash and put it in and it was reading that i had a full tank. is there a specific way to calibrate your fuel guage? i was told that i would need to fill the tank up.....and then point the needle to full,...thus calibrating the guage. don't these guages have a tendency to"fall" by gravity? i don't believe i understand exactly,.... this theory of how to recalibrate the guage to match what you have in the tank.so if all of the components are working properly (sending unit, good un-broken wire from sending unit to fuse box, and fuel guage) shouldn't the guage show the amt. of fuel w/in the lines ("E"-"F")of the guage? do you need to give the guage the position to represent "FULL"? or should it do that itself? sorry the post is so long, just trying to fully convey what i'm wantin' to say! thanks for any and all replies.

[JimKshortstep4x4]

There is no stop on the needle. What I did is set mine with the sender wire grounded so that it would read empty. It would work the other way, also. With the sender wire grounded I set the needle so that it was just below the empty mark. It is just a matter of pulling the needle and reinstalling it where you want it to read. Of course you will want to recheck it after you are done.

Jim

[Huck]

If your sending unit is good, and you are sure the wire from the tank to the dash harness is not shorted, and you checked the ground from your dash cluster to the dash metal, you should not need to re-calibrate the gauge as it is electronic and senses the location of the float via a reostat type coil. There is a resistor that is mounted between the two connecting points of the gauge that can go bad---personal experience--so you might try that before you pull the needle. Also---there are TONS of used dash bezel gauges available ---so I would tend to do that as they are dirt cheap.

[BobbyK]

Make sure the float on the sender isn't bad.

Over time some floats can partially or fully fill with gas giving you false readings at the gauge.

Pull the float and rule that out.While its out,connect it and move the float arm through it's range of motion.Look at the gauge while doing this and see what happens.

I had problems with my gauge when I first got my Blazer but it was a easy fix....just a grounded lead wire.

Good luck.

[BUXMAN66]

i guess i wasn't quite clear in what i was trying to explain in regards to the needle..... i wasn't meaning that you needed to REMOVE the needle and re-position it in the place you want it at, i was just meaning to re-point it in another direction. much like you would do in turning back the hands on your wall clock (and not using the dial wheel on the back-side). both replies are good information,and thanks.......but what i'm asking is do you need to give your fuel guage a reference point in what exactly is "F" ? what keeps your fuel guage from reading "F".......down at the bottom of your guage? this is what i'm talking about in terms of "calibration".

[JimKshortstep4x4]

Moving the needle or adding resistance are a couple of options.
With "0" ohms, the gauge should ready empty. With 90 ohms, the gauge should read full. If it does not work that way, you are probably better off getting another gauge.

Jim

[BUXMAN66]

the guy that is fixing the tach dash (had temp. guage problems and fuel guage problems) is replacing the temp. guage w/ a new one and replacing the fuel guage w/ a workable replacement.he tried the dash in his own personal truck to check it and he said he needed to "recalibrate" the fuel guage by filling the tank up and physically moving the needle to "F" to establish a reference point of where "F" is at, in relation to the needle point and the guage lines. if all else fails i'll just remove the fuel guage from my old WORKING dash,and be done w/ it.

[BUXMAN66]

anybody know what i'm talking of?

[BobbyK]

Whoever made the gauge,GM or a vendor, would have calibrated it originally.

Depending on whether that needle has ever been taken off that gauage it should already be calibrated.

The electronics in the back of the gauge will move that needle depending on the resistance reading it gets from the float.If the needle has been removed and then replace incorrectly somewhere along the line then no matter what you do that gauge will be off.

Did you say you checked it with another gauage that you know IS working?

[Longhorn Man]

Onless the needle was removed, then there is no way to calibrate it at all. You can put the needle whereever you want, once you put power to it, it's going to go to where ever it wants to go.
Grounding out the sender wire, and removing the needle and putting it E will make it inacurate. The needle should swing to the 9 O'clock position (Or close to) when you ground it out.

[tom hand]

You should never have to remove the needle...the gauge is calibrated from the factory. If it doesn't read correctly, ethier someone has had the needle off before, the gauge is bad, or you have a float/sending unit problem. The only way I will adjust how a fuel gauge reads is to bend the float rod in the tank to make it read correcty

[BUXMAN66]

these are exactly the my thoughts!so to be told to "fill up the tank and place the needle on FULL",..... ain't gonna actually work! ithink i'm gonna print out this thread just so i have a hard copy of it to study/refer back to when i'm ready to put the dash back in. thanks to all for the responses!

[OhioDan]

Originally posted by tom hand
You should never have to remove the needle...the gauge is calibrated from the factory. If it doesn't read correctly, ethier someone has had the needle off before, the gauge is bad, or you have a float/sending unit problem. The only way I will adjust how a fuel gauge reads is to bend the float rod in the tank to make it read correcty

Buxman, I know it's not the same thing, but it works on the same principal. This is the way we calibrate a fuel gauge after replacing the gauge or the sender on forklifts that we service. You can do it while holding the sender in your hand. Connect it up, turn the key on, then all the way down with the float should read empty, 1/2 way though the travel should read 1/2 full, and then all the way up should be full. Just my $.02 .

Dan

[BUXMAN66]

thanks dan ! i should be getting it back shortly,so i will be thinking 'bout whether i will need to take the sending unit out or not. i really don't think i will need to, but it's good information none the less. my fuel guage and (obviously) the sending unit worked perfectly in the old dash assembly that i took out to replace w/ the tach dash.so i think the problem was in the fuel guage that was put in the new dash. good thing is, i've learned quite a bit in how the whole fuel/guage system works. hopefully i can use it on future projects!