gas guage reading

[DanoDMano]

My gas guage when full reads 3/4 tank and when empty goes far below empty.

I know that we have 0-90 ohm sending units. Should it read 0 ohms at empty and 90 when full, or the other way around?

Is there an easy way to calibrate the guage?

Thanks, Dan

[71GMC_3/4T]

If the wire is open, it goes waaay past full, so that would be the high (90 ohm) end of it.
When the wire is shorted to ground, it goes to E and that would be the 0 ohm end of it.

I would suggest disconnecting the brown wire at your sending unit. If your guage goes way past full, the guage is probably alright.

You might want to put in a 10 or 20 ohm resistor in series with your sending unit wire and see if that makes it work in the range you want. I don't know what currents are involved, but they should be fairly small to prevent fuel ignition (which would be bad). You can probably get away with a 1/4 watt resistor from Radio Shack, although a 1/2 watt would be easier to work with.

[krazy_texan]

i think you have a problem with your gauge mine was doing similar a while back but when full it was reading at 1/4 tank i tried everything, even bought a new sending unit and harness, but it came up to be the gauge.

[SWEET7T]

71GMC_3/4T
OOOOoooo.... good call on the resistor!!!! I would go with the 1/2w resistor. I know that not alot of current goes through that wire, but better to have too much, than not enough.

[DanoDMano]

Yeah I think that mine is the guage also. It didnt start happening until I installed a new bezel!!

Good advice on raising the resistance for the guage, I think I'll try it. I would like to keep everything to stock specs though. I will be installing an underbed tank someday!!

Thanks for the great advice as usual!!!