1999 RX300 AWD. Drips fuel only when tank is full. Drip stops once 2-3 gallons used. Tank was removed and inspected. Leaking breather tube gasket (feeds one of two lines to filler neck) replaced. P0440 code once tank replaced. EVAP hose leak found and repaired. No more codes. Tank still drips only when full. Tank was smoked with no black light leaks seen. Gas cap sealing surface and gasket are good. Tank leaks with cap on/off, engine on/off. Tank is filled only until filler "clicks" ... no forced feeding. Fuel tank still dripping only when full. Any ideas?

 

Since you state it is dripping, did some one physically trace the drip/wetness to its source? If the repair was done based on other observation, then the root cause of the drip was not addressed.

There are two other things to consider ...
When, we the tank is full due to distribution of weight and how the tank is attached, the cracks/openings are different.

Incline changes the level too. My son's car would smell of fuel when we filled the tank and brought the car in the garage. Never had a drip but found a crack in the pipe near the far end of the car.

Salim

 

In the BMW world (where I'm most familiar) the vent lines on top of the tank crack and can drip/smell when the tank is all the way full. I would focus my efforts on the stuff on top of the tank, if it doesn't leak when it isn't full the problem has to be on top (or near the top). I would look at some of the other work done on the top, they may not have actually fixed the problem.