The only experience I have with lighters is the disposable kind that you use to light candles. But when I was at an antique shop recently, I saw a vintage lighter that I thought looked cool. It didn't work, but I decided to try to figure out how to restore it.
Searching online was difficult since I knew next to nothing about lighters. I didn't even know what words to put in the search bar to find what I needed. I ended up asking some coworkers, an employee at a smokeshop, and a gas station employee, and I eventually found what I needed!
Please use common sense and do your own research, I do not take any responsibility if this goes disastrously wrong.
It seems like this style of promotional lighter was pretty common at one point in time, so even if yours isn't a Budweiser lighter you may be able to use these instructions to refill it.
To refill the fuel in your lighter you will need a butane fuel canister (below, left) and flint refills (below, right).
I purchased both of these at a convenience store that was recommended by an employee at my local smoke shop. You can also purchase these online.
First, you need to make sure there's fuel in this lighter. Take a flathead screwdriver and unscrew the bottom of the lighter.
You should see a small valve inside. I'm not sure the name of this valve but it reminders me of a schrader valve on a bike tire.
I followed this youtube video to refill the butane.
When I followed the first step, to bleed any air out of the lighter, I didn't hear any hissing. This means the butane fuel chamber was already full! I topped the fuel chamber off with the butane refill canister, but it was already full.
Next step is to refill the flint. There's a smaller screw on the opposite of the lighter from the sparkwheel.
I removed this screw with a smaller flathead screwdriver and only a spring came out. This spring is what will hold the flint in place and push it closer to the spark wheel as the flint wears down. I shook the lighter just to make sure that there was no flint stuck in there. The picture below shows what the lighter and spring look like when disassembled, as well as the small piece of flint I put into the chamber.
Drop the flint refill into the flint chamber and screw the spring back into place. Now you should be able to test your lighter.
Open the top of the lighter. Flick the spark wheel to the left. You should see sparks fly and a flame appear. If sparks do not fly, check the flint. If a flame does not appear, the problem is the fuel. You should do this outside, just in case something goes wrong.
When you want the flame to go out, you close the top of the lighter.