Gas Gauge Stuck?

[tomfg]

Fill up gas tank all the way today on the 64 for the first time
since I've had it on the road. Went on a 90 mile shake-down
cruise, and the gas gauge never dropped off of full.
I know it actually burned gas, as I filled it back up
when I got home to calculated the mileage, and had
to add 8.45 gallons.
The gauge did seemed to operate okay between
empty and 1/2 tank before today when I filled it all
the way.
Is it possible the float is stuck, or that something
else happened? I did have the float out when
restoring the truck to inspect it, and don't remember
any mechanical issues with it.

Also, the gas milage came out to 10.76 mpg.
Does this sound about normal, having
a 350, with a 2 barrel, sm420 4spd, and
3.73 gears in the rear? The tach is showing
about 2600 rpms at 55 mph.

Thanks for any input.

[1963c-10]

I would pull the sending unit out of the tank for a good inspection. Will also allow you to inspect the inside and bottom of the tank. Move the float by hand and see if any change in the guage.

[tomfg]

I have a full tank, so will have to put some miles on it before I can pull the sending unit out of the tank.

Is it the wire from the fuse panel being off, or the ground wire at the sending unit being off, that will cause the gauge to read high? I remember some issue with the gauge reading full (with an empty tank) when I first put the truck back together.

[kenmel]

I would like to know to. Mine reads full all the time and have tapped on the guage with the key off and it will drop to half. Then when key is turned on right back to full. driving me nuckin futz. lol

[1963c-10]

If the guage reads full, regardless of the position of the float arm, a short in the wiring between the guage and the sending unit. These guages read on 0-30ohms, I would check with a meter and see what your getting at both ends.

[tomfg]

Are you saying to "stroke" the float with
the ohm meter hooked up, and I shoud have
zero at one end of the spectrum, and
30 ohms at the other?
Thanks.

[bigdlb12]

Hi guys new member here, mine 1960 does this too, I dont normally fill her up since I only drive her on the weekends, but it normally would stay near full to 3/4, the one time I did fill up I notice the gauge was on full for the whole weekend, so I tapped on it and then it moved, I dont think it is my floater, but maybe something in my gauge

I have a back up cluster so I will open it up and check out that guage and clean it then swap

on another note, I get about 10-12 MPG , both city and highway driving

I have a 350 with a 350 tranny, mild cam and a 750 cfm carb, it is an edlebrock so the prim and sec are the same size, not too sure on my gears tho, the rearend is off of a 1969 firebird

[1963c-10]

You will want to pull the sending unit. Either apply jumpers to the wires or leave attached. Turn on the ignition and test the float arm. The guage should range from full to empty with the arm moving. If the guage acts funny, check to make sure that it is tightly grounded and both wires are hooked up to the back of it. If the guage reads full regardless of the position of the float arm...there is a short between the guage and the sending unit. If the guage operates proper, then it is the sending unit. If doing the test with a meter...should be 30ohms full 0ohms empty.

[1963c-10]

Also...check the resistor on the back of the guage to make sure it hasn't burnt out. Check to make sure that your wire's are correct also.Power should go to the empty side of the guage and the sending wire on the full side.