The oil level in the pump is low.

1. Add power steering fluid as required. Refer to Checking and Adding Power Steering Fluid .
2. Inspect for leaks. Refer to Power Steering Gear and Pump Leaks .

The pump belt is loose.

Refer to Drive Belt Replacement in Engine Mechanical 4.3L.

The pump pressure is insufficient.

Refer to Power Steering System Test .

The gear relief valve is faulty.

Replace the gear relief valve.

The drive belt tensioner is weak.

Refer to Drive Belt Tensioner Diagnosis in Engine Mechanical 4.3L.