electrical and ignition Fuel Gauge Only Reads 'full'

[frostyspeed]

If only it weren't lying.... To have a bottomless fuel reserve! Sadly not the case.

Anyone ever had this one? Doesn't matter what level the tank is at, gauge reads Full.

I just replaced the whole cluster so almost for sure I know the problem is the gauge itself.

Just looking to see if someone knows how to fix it

-Frosty

[182kartracer]

I don't have the same problem but i have another annoying one. After i reach half tank my gauge starts bouncing around like crazy. I could also used some advice. 

[bills2002]

"I just replaced the whole cluster so almost for sure I know the problem is the gauge itself."

 

Is this what you meant to say Frosty? The other gauge worked in the old cluster but the new cluster's fuel gauge isn't working. Just swap multi gauges and call it a day. Or...do you mean you replaced the cluster and almost for sure know the problem is the sender? Try swapping the wires on the sending unit (in the trunk).

 

Check grounds, check grounds, CHECK grounds. For both of you.:-)

[jimk]

The signal wire from the sender is shorted to ground or you lost ground to that gauge.

[frostyspeed]

"I just replaced the whole cluster so almost for sure I know the problem is the gauge itself."

 

Is this what you meant to say Frosty? The other gauge worked in the old cluster but the new cluster's fuel gauge isn't working. Just swap multi gauges and call it a day. Or...do you mean you replaced the cluster and almost for sure know the problem is the sender? Try swapping the wires on the sending unit (in the trunk).

 

Check grounds, check grounds, CHECK grounds. For both of you.:-)

Yes. I replaced the whole cluster. Back dated my '74 fake wood to a '68 all black style. I sold off the old (working) cluster before I knew the fuel gauge had malfunctioned...

Copy the grounds check. TBC....

[baller908790]

I had the same problem. The wire running through the fuel sender was cut. 

Bought a used one and the problem went away.

[M3M3M3]

Check grounds, check grounds, CHECK grounds.

 

 

The signal wire from the sender is shorted to ground or you lost ground to that gauge.

these.

 

and check the sender.  if grounds check out, pull sender out of tank and test resistance right side up and upside down.  

[Mike Self]

A gas gauge that twitches all the time probably has a bad ground, either at the gauge itself or at the sender unit.  Lotsa archives on grounding the temp and gas gauge.  If it twitches only when partly full, it's probably crud on the resistance wires inside the sender unit.  There's a plastic float that rides up and down on the resistance wires, varying the ohms and thus the reading on the gauge.  You'll need to carefully dismantle the sender (see archives for how to) and VERY gently clean the wires with carb cleaner, laquer thinner etc.

 

mike

[Dabliz02]

+1000000  on a bad ground.

 

first place to start

[FunkyLaneO]

The sender wire is probably shorted out to ground somewhere, try unplugging the wires from your gas tank sending unit and see if it still reads full, if it does then your gauge is receiving a 0 ohm ground signal from somewhere.  A bad ground to the gauge will cause it to flutter or read low, not full.

 

The gauge could also be bad, you can actually remove it from the cluster and test it independently with a power source, some alligator leads and a couple resistors (or a variable resistor that will work in the range of 0-75 ohms)