Is there a way to unit test or debug a web api in one vs solution? I am consuming the WebAPI using HttpClient and have two instances of VS up to do this.
in 1 VS instan
As Daniel Mann stated, this isn't unit testing. This is integration testing. You are running up the entire project and testing everything.
If you want to unit test you webapi controllers, just add a unit test project to webapi project and create unit tests. You want to focus on testing only a single class at a time. Mock/Fake any dependencies of that class.
Here's a nice example from Microsoft http://www.asp.net/web-api/overview/testing-and-debugging/unit-testing-with-aspnet-web-api
but if what you are looking for is running the test you have in a single solution. Just put both projects in the same solution. Right click on the solution in the solution explorer. Select "Set StartUp projects." select "multiple startup projects" and select the projects you want to startup at the same time.