Where is your fuel injector Yukon99?

A 1999 GMC Yukon's fuel injectors are located on the intake manifold, above the engine. To be more precise, you'll find them in the intake manifold, one for each cylinder. You'll have to remove parts of the intake manifold to access them for service or replacement. Because their location is inside the intake manifold, it’s not something you can simply see by looking at the engine bay.