Gas guage only registers 1/4 full

[8door]

Here we go again.
Got a new tank sender, checked the power connection, made sure
tank is grounded as well as the base of sender where it sits on tank.
I know tank is FULL of fuel but ithe guage only registers 1/4 full.
Took the sender out again made sure power and grounds firmly connected turn on the switch slowly moved arm to maximum sure enough guage stopped at 1/4 full.As I slowly moved arm back down the guage started to move toward empty.
Then disconnected ground and guage moved all the way to full.
What am I missing ??????

[LockDoc]

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Off the top of my head I would say that the gauge is bad in that situation. I think I would remove the sender and check it with an OHM meter. It should read 0-90 OHMs depending on where the float is at when moving it by hand. 0 ohms in the empty position, 90 ohms in the full position.

LockDoc

[TBONE1964]

When you had the sending unit out and was moving the arm back to empty, what did the gauge do at empty? Did it go way beyond empty, lets say around the 9 o-clock position or did it stop right on the empty mark.

From your description, it sounds like everything is wired up correctly and has good grounds.

Is the gauge you have original to the truck or has it been replaced?

[8door]

Locdoc---- ohms are 0 at closed(empty) 90 at open (Full)
Tbone----- Guage needle sits exactly on empty not before not after the mark.
Guage as for as I know is original to truck.

[TBONE1964]

Originally Posted by 8door

Locdoc---- ohms are 0 at closed(empty) 90 at open (Full)
Tbone----- Guage needle sits exactly on empty not before not after the mark.
Guage as for as I know is original to truck.

If that is true then I would bet on the gauge being bad as LocDoc mentioned.

The other thing you can test is to put 12V and ground on each side of the resistor on the back of the gauge. On way it should go to the empty mark and the other way (reverse the hot and ground) the gauge should go just past full but not far. You will want to disconnect the connector on the back of the cluster before doing this test.

[8door]

Originally Posted by TBONE1964

If that is true then I would bet on the gauge being bad as LocDoc mentioned.

The other thing you can test is to put 12V and ground on each side of the resistor on the back of the gauge. On way it should go to the empty mark and the other way (reverse the hot and ground) the gauge should go just past full but not far. You will want to disconnect the connector on the back of the cluster before doing this test.

I'll pull the instrument panel and do your recommended test.
One other thing I did was gradually moved the sender arm and noticed the guage read about an 1/8 th with the arm about 1/2 way through it's arc of total swing.
You guys are probably right, bad guage. Well maybe not "bad" just old like some
of us and will only move so far............
Thanks gents.