Will this plug directly into my washer system without adapters?

Yes — electrical connector and mounting points are OEM spec for 05-08 Frontier models. Drop-in replacement with no wiring modifications.

Do I need to drain the washer fluid reservoir before swapping pumps?

You can work with fluid still in the tank, but draining first makes removal and reinstallation cleaner and prevents spills inside the engine bay.

What if the pump runs but no fluid comes out after install?

Check that hose connections are seated fully at both the pump outlet and reservoir inlet — air leaks kill flow. If connections are tight, the reservoir intake line may need cleaning.