The test is: (if you can get to sender); Remove sender wire from float, it should show full. Will show empty when sender wire held to ground. If it passes, hook up sender to float and ground sender flange, should show full if tank IS full. Work float up and down.
Note: Not sure what you did? If cluster is out, were gauges grounded? Did you remove sender wire from Gauge for the "FULL" test? If so, remove sender wire again from gauge, add a test wire to ground for "Empty" test. Of course you need power to gauge during tests. Gauge body must be grounded.
