You'll need to:
1. Locate the under-hood fuse block: This is usually a rectangular box, often black plastic, near the battery.
2. Consult your owner's manual: The best way to find it is to look at the diagram in your owner's manual. It will show the layout of the fuse block and identify the fuel pump relay.
3. Look for a diagram on the fuse block cover: Often, there's a diagram on the cover itself that shows what each fuse and relay does.
4. Check online resources: Searching for "1987 Chevy Scottsdale fuse box diagram" online may provide you with a picture that shows the relay's position.
Important Note: Be sure the vehicle is turned off before attempting to locate or remove the relay. Improper handling of electrical components can be dangerous.