Faulty Fuel Gauge

Hello,
Could use some help with my faulty fuel gauge. When I disconnect sender wire (hot) at rear trunk gauge goes to "F" or above. Now, when I use a jumper on this same wire and ground it gauge goes to "E." I then ran resistor tests with different values to mimic the sending unit. The results were" 22ohms = just above "E", 47ohms = 1/4, 68 ohms = 1/4, 100ohms = 1/2
Now, I am lead to believe the problem is forward from sender wire to the fuel gauge. Would the problem be bad gauge or somewhere in the wire to the gauge. I would like to find out before I take the gauge out to inspect. Thanks for your time
 
That sounds like you have tested the gauge quite well, so I would think the problem lies in the sending unit.
 
Before you drop your gas tank, check under your trunk mat for an access hole. I am sure at least the Riviera had one.
 
The crazy thing is the sending unit is new and was tested before the install. So, this is why I am leaning towards bad gauge since it's not measuring the resistors correctly.
 
Check the harness between where you unplugged it for testing and the sending unit. Sometimes where it goes through the floor is the problem with frayed shielding and copper oxidation causing high resistance or an open condition. Also what Bob suggested above is a common problem.
 
What year vehicle are we talking about??? '64 & earlier were 45 ohms. '65 & newer were 90 ohms. Since your ID says "BoattailLou you have a newer vehicle than '65 as the Boat Tails were '71-'73.
By removing then grounding the wire in the back & the gauge went full empty to full full you have tested the wiring & the gauge from the rear to the front & it's functioning correctly as it should.
The next thought is bad connections/grounds.
I'm sure that's where you'll find the problem/problems. All it takes is a little corrosion/bad connection to give the symptoms your describing.
Just my thoughts.

Tom T.
 
Well, think I finally figured out what was causing my troubles besides bad fuel gauge. After sanding the surface and reattaching the sender ground wire several times the gauge and sender now seem to be working properly. Never thought I would have to do this several times to get a good ground connection. Thanks to all those we replied to help me out. I really appreciate it!
 
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