At least some Pipers have the locking open type of fuel drains.
Actually I think there's an informal recommendation, being carried out by owners and operators around the world, to file away the "lock open" lip on the fuel drain so that it cannot stay open anymore by itself. For obvious safety reasons - pilots not making sure the drain is actually locked properly after draining.
According to Jeremy Pratt in the Pilots Guide to the PA-28 Warrior (pg. 21) this has happened to the engine fuel strainer where people tried to drain with the fuel selector in the "OFF" position. So the dumping of fuel started only when people finished their walkaround, got into the cockpit and opened the fuel selector. No problem during runup and taxi, but the fuel would be totally drained just after take-off.