[Carbuff2]

Sounds as if you have either a shorted or open (broken) wire going to the gauge cluster. (Some senders provide more resistance at empty, some less)

First action is to plug/unplug the connectors to the gauges 3x, in case there is a high resistance/broken wire there. Visual inspection, too.

Is the LOW FUEL light on? That MIGHT be a clue, not sure.

++++++++++

If all this is too much, just be diligent about resetting the trip odometer at each fill-up. We start looking for gas stations at about 250 miles on a tank.
Our LOW FUEL light comes on at about 320 miles, and the car takes ~ 14 gallons of 15.3 under those circumstances.

 

[Carbuff2]

You already tried new sending units, so it not likely to be THAT plug. (Unless that is where a broken wire is)

But as the low fuel light works, I'd def. be pulling the instrument cluster and looking around.

 

[Carbuff2]

If a visual inspection doesn't reveal anything, a few hours with a wiring diagram and VOM meter is warranted.

++++++++++++++

Years ago, I fixed a lot of issues with my sister-in-law's Nissan. One of the issues was a broken wire trace on the circuit board of the instruments, which I repaired with wire and a bit o' soldering.

After I gave her the car back, she called me and said "THAT hasn't worked since I bought the car used!!!"

 

[Carbuff2]

Great find.

I think USA models are KA. (so, non-KZ connectors apply)

See what the resistance readings are on the duplicate fuel pumps that you have. Tho' the Parts Cannon approach would seem to indicate that the issue lies elsewhere.

You need to find the inputs to the cluster.

 

[Carbuff2]

Possible, but more n likely, those varmints were chewing on yer wires. <---said in my BEST Yosemite Sam voice

You should be able to clean the cluster-nest and eliminate any shorts. Do the final rinse with alcohol, and let it dry overnight before re-installing. ( It HAS to be dry. Inspect before plugging in)
Repair the chewed wires. Wrap with Honda rodent tape or equivalent.
Honda 4019-2317



Post back with results.

 

[Carbuff2]

You seem to be obsessed with the pee.

This is WAY outside of my area of expertise, but aside from a smell, won't the pee have dry up after you clean the mess?

 

[Carbuff2]

Apparently it IS conductive... sorry.

How well does urine conduct electricity?

Answer (1 of 12): Really well. It's water with charged particles in it. That is water with electrolytes in it. People peeing on the third rail of trains have been electrocuted for this ability of urine to conduct electricity

www.quora.com