Where is the power steering pump on a 1991 ford explorer?

On a 1991 Ford Explorer, the power steering pump is located on the front of the engine, driven by a belt. It's usually attached to the front of the engine block, near the crankshaft pulley. You'll likely see a reservoir (the power steering fluid container) nearby, connected to the pump by a hose. However, without knowing the specific engine (4.0L Cologne V6 is most common, but there might have been others), a more precise location is difficult.