onelayerawaytop

local function checkFuel()
    while turtle.getFuelLevel() <= 200 do
        turtle.select(16)
        turtle.refuel(16)
        turtle.select(1)
    end
end

while turtle.detectUp() == false do
    checkFuel()
    turtle.up()
end

while turtle.detectUp() == true do
    checkFuel()
    turtle.digUp()
    turtle.forward()
end

while turtle.detectDown() == false do
    checkFuel()
    turtle.down()
end