Will this pump work with my factory washer fluid hose?

Yes. This pump uses the same hose connections as the original, so your existing lines connect directly without adapters or splicing.

Do I need to drain the reservoir to install this?

You can install without draining, but you'll have easier access if the reservoir is empty or nearly empty beforehand.

What if the pump doesn't come on after installation?

Check that the wiring harness is fully seated into the motor connector and that your washer fluid level is adequate. If fluid is full and connection is solid, test the washer switch and fuse per your service manual.