Seeking Assistance / Fuel Gauge Inoperative

[Synoptic 12]

Seeking some assistance regarding the fuel gauge reading. After filling up, the fuel gauge was pegged (full) for two three days. After that time, it now reds about 1/2 full, Whether it's accurate is unknown. The pink wire located at the rear bumper was disconnected and each end was grounded to the chassis. The male end (grounded) brought the fuel gauge to 'full' while grounding the female end brought the fuel gauge to 'empty'.
1.) Would this be a fuel sending unit.

2.) I'm uncertain if the float was stuck, bad resistor, or bad ground (open circuit). All replies are appreciated.

3.) 1986 Oldsmobile Cutlass Supreme Brougham- 5.0 Liter Vin Y.

 

[Rocketman269V]

View attachment 1538 ............. The pink wire located at the rear bumper was disconnected and each end was grounded to the chassis. The male end (grounded) brought the fuel gauge to 'full' while grounding the female end brought the fuel gauge to 'empty'...........

Grounding the male end should have NO effect on the gauge reading, as it's not connected to any wiring in the car. Grounding the female end should give a "full" reading and beyond; disconnecting the plug, as you did, should yield an "empty" reading and beyond, meaning off of the normal range of the gauge.

 

[Synoptic 12]

So, is it the sending unit? Thanks very much.

 

[Rocketman269V]

After re-reading your original post, I realized that when you grounded the male end, you basically were just observing an open circuit at the female end, which is how you would check the gauge. So, yes, I would say that you need a new sending unit.