Hello! I just registered today after buying my silver 2009 FX50S this weekend. I have been researching and shopping this particular model for several years. I refuse to buy a new car, so with that comes used car woes. It's ok because I love to wrench. So, I have had my car 2 days and I think the pump is whining and going bad. I did all the typical searches...Google, Rockauto, Autozone, etc to see what a tensioner pulley costs BEFORE I assume it's the pump. There doesn't seem to be any info on this part. What gives?

First apply vacuum to the power steering pump reservoir with the engine running and turn the wheel back and forth a few times. I've done it before using a shop-vac and some ingenuity to get a tight fit around the reservoir cap. The vacuum will get any air out of the system which can cause the P/S pump whine.

That seems simple enough. Perhaps the cap is not making a good seal and is letting air into the system. Sounds like a good starting point. Thanks!

Air can and should be in the reservoir. It does not have to be air-tight. Infact, I once drove my last car with the reservoir cap off for some thousand miles (oooops). Luckily non splashed out but the pump never made a sound. Its air in the pump that causes the whine. Only way to extract it is with vacuum.