Your best bet is to:
1. Consult your owner's manual: This is the most reliable source.
2. Look in the underhood fuse box: The fuse box is usually located near the battery, often on the driver's side fender well. Open the cover and examine the diagram printed on the inside of the lid. The diagram will list relays and fuses. It might be labeled "fuel pump," or refer to a specific circuit related to the fuel pump.
3. Check online forums and repair manuals: Websites like Buick forums or repair manual websites (like Chilton or Haynes) may have diagrams and discussions specifically for the 1994 LeSabre, but always cross-reference with your owner's manual if possible.
Be careful when working near the battery and electrical components. Disconnect the negative battery terminal before working on the fuse/relay box if you are unsure.