Using JD's info I was able to find the O-rings you need are JIS P3. The dimensions are 1.9 mm x 2.8 mm. ...If you cross that to American it is 1/8" ID x 1/4" OD x 1/16" cross section. It would have a part number of -006 (pronounced "dash 006") Sometimes refereed to as A006.
Just went out to my shop and found my Harbor freight kit included 20 of them. Here is a link and if you look close at the second image top row you can read 1/8 X 1/16. These are nitrile and good for gasoline. All for $5.00.