View difference between Paste ID: u2Ej1ZN8 and NNP8acK8

 function digF()
 	while not turtle.forward() do
 		turtle.dig()
 	end
 end
 
 function digU()
 	while not turtle.up() do
 		turtle.digUp()
 	end
 end
 
 function digD()
 	while not turtle.down() do
 		turtle.digDown()
 	end
 end
 
 function detectU()
 	while turtle.detectUp() do
 		turtle.digUp()
 	end
 end
 
 function detectD()
 	while turtle.detectDown() do
 		turtle.digDown()
 	end
 end
 
 function tF()
-	if turtle.getFuelLevel()=0 do
+	if turtle.getFuelLevel()>0, than turtle.getFuelLevel()==0  do
 		turtle.refuel()
 	end
 end
 
 print("Enter lenght vaule of corridor")
 local lenght=read()/2
 
 for i=1,lenght do
 tF()