gauge help please

[gt fast]

so i had to replace some light bulbs behind my gauge cluster on a 1992 ford explorer. now i removed all the needles from the cluster before i realized there where screws i coulda taken off instead. my probem is since this my fuel gauge seems to be not right. when i put it back on i went to the gas station and filled the tank. then wait about 15 minutes just to make sure the needle would of been all the way up as before, then i installed the needle. now it seems like i dont get as good of mileage, like today it said alittle under half tank, i put 5 gallons in and it almost when to full. someone help how can i calibrate this.

 

[Roadrunner777]

Here's what I would do: Put some gas in a can and throw it in the back. Now, drive your normal routine. At some point, you will run out of gas. You will know when it starts to starve, that's good enough. Look at the gauge and see how far it is off of empty. Make a note, take a picture, whatever. Pour your gas can in and drive to the gas station. Later make that adjustment on the needle.

If you want a more immediate solution, you can find the Y/W (yellow/white) lead from the fuel pump/sender and test it's resistance to ground, the spec it says is 145 for full, 22.4 for empty. You can pick up this lead at one of the connectors with 8 wires near the master cylinder. before it goes to the firewall connector. Measure the resistance, and do the math.

Personally, I really don't care how accurate my Full is. I'm really interested in how accurate my Empty is, and the first method is the way to go for an accurate Empty.

 

[Maniak]

That method is what we used except I did it for 1/2 tank as that was the setting I wanted accurate. I knew then had to learn where empty and full was (had to run it to empty again to find empty).. At that point I know where it reads and all is fine.

~Mark