Fuel gauge reads 1/2 when full

[69Panther]

The gauge is stock. (It is the small gauge between the speedo & Tach.)
It was not used by previous owner.
I got a new sending unit & it seems to check out at the trunk (used a different gauge to test it and it worked well).......



The original gauge reads just under 1/2 tank when full. The needle moves as I filled the tank... but stopped at 1/2.
I jumpered the ground, hot & sending unit wire on the original gauge. It has the same 1/2 full reading..so I guess there is a good ground etc.
Not too good with electrical stuff
It looks like the gauge is reading wrong. I really don't want to replace it...
Can I use a resister in line to "fool" the gauge?
Is there another check I can do?
Thanks for your help.

[dstryr]

I think its the sender? what company made it? ive heard of some of the ones classic and npd sell are faulty...so might want to check that out. Search the brand name in here.

[69Panther]

I think it was Summit...I'd have to look.
I checked the sending unit at the trunk with a different gauge. It seemed to work fine..

[dstryr]

Wait...so you are saying that with a different gauge it works...but with the one in your dash it only reads half full? seems like you need a new gauge :p

[matty b]

ok all you need to do is disconnect the sender wire at the sender and see if the gauge reads full if i does not you got a bad gauge, this is assuming you have a gm. if it does go to full, your gauge is fine and you have a sender issue that could be a variety of problems from a busted resitor strip to a bent up float rod.

[69Panther]

I unplug the sening unit, it goes full. Plug back in and goes to 1/2
I gues I'll run the tank MT and check the unit.
Thnks

[protour73]

empty the tank, remove the sending unit. Take a multimeter, select Ohms, with the float in the down (or empty) position, attach one of the meter probes to the ground wire, the other probe to the stud (on the sending unit) that sending wire for the gauge attaches to, it should be next to spade connector for the ground.

In the empty position, should read 0 Ohms (or close to it). Raise the float to the full up (or full) position, meter should read approximately 90 Ohms. If not junk the sender. Don't buy anything but a Spectra Premium sending unit, the other choices are junk. It can be ordered from http://www.rockauto.com/index.php?a=G-autoparts

[John Wright]

should read 0 Ohms (or close to it).

Scottie,
If you put the ohms meter on it and you find that it is open when the float is down in the empty postion.

....could that be where the gas ran out?