Fire will hurt, and kill, them, but unless the chainsaw blade is solid Steel (not stainless), solid Copper, or solid Titanium, and enchanted, it won't even put a scratch upon a Vampire. Yes, Vampires are notoriously hard to kill. Which is why you need to go after them in packs, or groups.

Or find a way, by enchantment (a spell) or by blood (a Werewolf biting you), to become a Werewolf. For Werewolves are faster, stronger, and more agile than Vampires.



(If the chainsaw blade is Sterling Silver, it doesn't need any enchantments upon it to be effective. It will work on it's own. But I don't think any Sterling Silver bladed chainsaws exist.)