The Minecart with a Furnace can only accept Coal and Charcoal as fuel and cannot take other sources as fuel such as Planks, Lava Bucket, Dried Kelp Block etc.
- Set a track with a Minecart with a Furnace
- Put Coal and or Charcoal in it
- Watch the Minecart go
- Put Block of Coal, Dried Kelp or other source of fuel in
- Watch it not go