Please help thanks : 300 Verado 2007 .. # 6 cylinder hydro locked with fuel

Ok we are going out ... And barely hit a tree stump on the port motor ....
Engine then dies .... After checking fuel pressure ... We only had 15lbs ... Then after cranking the motor locked up ... Upon removing the spark plugs #6 cylinder was full of fuel ... Enough to lock the motor ?
What could cause # 6 to fill up with fuel ... I read there might be a defective vacume line in the fsm .... That ruptured causing the cylinder to fill with fuel ?

Any advice will help ... I have not removed the FSM yet ... But did check all injectors and the spray pattern is fine .... Thanks in advance ...