Here is said device:
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Mounts (O-Ring and Plastic Nut) into the bottom of the gas tank - has a neg and positive lead coming out the side and going deep into the tank.
That is the fuel level sender.
The wires entering the tank feed voltage to the fuel pump, which is accessed from the top by removing the cap and then the cap holder.
Those units have been known to fail both by no longer registering fuel level and also not feeding voltage to the pump.
You say your pump whirrs, so it is at least still supplying voltage.
You shouldn't hear fuel trickling unless the tank is almost empty. You're going to have to put that back in, don't over tighten and crack the plastic nut, and remove the cap and holder to check to see if you have a loose or split fuel line.
By the amount of 'mung' on the sender I wouldn't be surprised if the filter, which will be visible when you open up the top, was clogged.
An inexpensive aftermarket alternative is available from NAPA #3032. It isn't exact, but thousands have been used successfully.