It was a few years ago when I built my wing tanks ( slow build )
I took a real simple appraoch to my tank testing.
The leak check:- I tried the balloon test but had inconclusive results
So then I thought why not fill her up with gas 100LL and leave the tank on the work bench for a couple of days ? I checked the soft tissue paper the tank was sat on for leaks. After a few days i had no leaks
Testing the tank sender with the steam gauge proved that worked, so all a needed to do was check for flow & debris.
After hooking up the facit fuel pump and checked the flow with the pump running... no problems there. I don’t have my flow results now; but it was way more than the Lycoming could ever use.
I then drained the tank and used a fine funnel filter to check for crud;
Once the tank got down to 1/4 full we sloshed the rest of the gas around before continuing to drain absolutely nothing came out ! Simple as that