From Watson Lake, you need to make it to Ross River, there is one gas station there. Sometimes they're out of fuel though, so be prepared to go further or wait a few days for the fuel delivery.
Faro also has fuel now, but it is an unmanned station that takes debit/credit cards only. If the computer isn't happy, you can't get fuel.
Read more about the Campbell Hwy at my websight
http://yukonsights.ca/CampbellHwy.htmlBe prepared for rough road conditions, highway construction and mud.
There is only one campground with services, in Faro. The Yukon gov't campgrounds along the route are nice if you enjoy dry camping.