Analog temp gauge not working

[Randalls84GL1200std]

New member (63 years old) AND a proud brand new owner of my very first GoldWing! It’s a gorgeous, pristine 38-year-old Candy Wineberry Red ‘84 GL1200 STANDARD with 31,000 miles under it. Just a couple issues with it…
THE ANALOG *FUEL* GAUGE ISN’T WORKING. Its companion temp gauge is functioning normally so the problem is obviously not the 7-volt regulator that controls the both of them (I’m soon going to purchase one of the site owner’s $39 7-volt regulators just to have it handy if/when the old one fails). Any ideas on what I might look at to get the fuel gauge operational again?
Some background on the bike: The gentleman I just bought the bike from had bought it about a year ago from the widow of the original owner after the bike had sat unused in the original owner’s garage or storage unit for some time and had developed carb and brake issues from sitting so long. Since his purchase of the bike and prior to selling it to me, he got the brakes functional again and had the carbs dismantled, disassembled, and cleaned or rejetted so that it now runs and idles smooth like a brand new electric Singer sewing machine—or like a Honda product. It sure would be nice to have that fuel gauge functional.
The other issue is final drive gear oil leaking from around the bottom of the smooth cylindrical shiny cap just above the center of the final drive case. I haven’t removed the filler plug to check the level yet. I don’t know how it could be overfilled unless someone filled it while it was leaning on the bike’s side stand rather than leveled up on the center stand as the manual states. Assuming it’s not overfilled, is there some other possible issue that would cause gear oil to leak out around that shiny cylindrical cap? I tried twisting that cap to see if it needed tightening but it seems quite tight with no wiggle to it and with no grips to get any real purchase on, I assume it’s not a threaded cap and is pressed in or something? I initially thought it was the filler cap but the manual shows the plug that goes in the sight hole to be the filler cap. And the picture in the manual shows a final drive case that doesn’t even have the shiny cylindrical cap poking straight up on the side of the case that mine has? What’s up with that??
Thanks in advance for any direction or input from anyone familiar with these two areas!

—Randall

[Rambozo]

Disconnect the sending unit and measure it cold and then hot. Also you can ground the wire to see if the gauge part is functioning.

[Randalls84GL1200std]

I’ll be straight up honest. I’m a real idiot when it comes to anything electric. I assume you mean measure it with one of those electric current testing contraptions with the pointed probes that you touch to the terminals. I wouldn’t even know what setting to set the tester to… or what reading I’m supposed to be seeing or even how to interpret the reading it would give me. When you say test the sending unit “cold” I assume you mean test it with the wires/connectors disconnected from the blade posts on the sender? I’m sorry about my ignorance here and I do appreciate your reaching out to give me a bit of guidance, but when it comes to anything electrical, I’ve got to have the very elementary A, B, C directions with no skipped steps or I’m lost.

[Rambozo]

Ok, the easy way is to unhook the wire from the sending unit. With it unhooked the gauge should read all the way in one direction, then ground that wire and the gauge should read all the way in the other direction. If that is the case, you probably just need a new sender. If the gauge doesn't move for either of those tests, you need a new gauge or have a wiring problem.

[Randalls84GL1200std]

The sender (on top of the fuel tank held in by a locking ring) has 2 wires connected to it. One is a round post connector, the other is a flat blade connector. Do I disconnect them both or just one of them to do that test. And does the key need to be in the “on” position with lights on when I do it?

[Rambozo]

I thought your problem was the temp gauge?
For that you need to unhook the temp sender, not the fuel sender. It will be screwed into the engine near the thermostat housing and have a single wire. (the one with two wires is for the fans)
And yes the key needs to be on when you do the test.

[Randalls84GL1200std]

Quote from my original message…
“THE ANALOG *FUEL* GAUGE ISN’T WORKING. Its companion temp gauge is functioning normally so the problem is obviously not the 7-volt regulator that controls the both of them.”

[Randalls84GL1200std]

I should have said fuel gauge isn’t registering anything. It reads empty no matter how much fuel is in the tank. It may very well be the gauge itself that’s broke. Or the sender at the tank.

[Rambozo]

Ok, the title says analog temp gauge not working.
The test is the same but with the fuel sender.
Key on, disconnect the yellow wire, check the gauge. Then ground the yellow wire and check the gauge. Report back.

[Randalls84GL1200std]

Sure enough, I screwed up on the subject line and didn’t notice till you just called it to my attention. Thanks for pointing out my blunder and very sorry for the confusion. I’ve noticed that it’s easier to do things like that at age 63 than it was when I was younger. And thank you again for your effort to help me figure this thing out. I need to pull the seat and test the connection as you’ve suggested. I need to get a voltage meter from the parts store tomorrow so I can do that.