To find it, you'll need to:
1. Consult your owner's manual: This is the best place to start. It should have a diagram showing the location of all relays and fuses.
2. Locate the underhood fuse/relay center: This is usually a large plastic box, often near the battery.
3. Examine the relay diagrams: The cover of the fuse/relay center should have a diagram showing which slots are for which relays and fuses. Look for a relay labeled "Fuel Pump," "EFI," or a similar designation. The diagram might use a symbol or number.
4. If you can't find a clear diagram: You can use a multimeter to test relays in the underhood fuse box to identify the fuel pump relay. Caution: Be extremely careful when working with electrical components. Improper handling can lead to injury or damage to your vehicle. If you are uncomfortable doing this, it's best to consult a qualified mechanic.
5. Consider the Passenger Compartment Fuse Box (less likely): While less common, some Caprices might have a secondary relay in the interior fuse box (usually under the dash). Check your owner's manual to see if this is the case for your specific vehicle.
In short: There's no single answer without your specific car's details or checking the diagrams provided by the owner's manual. Referencing that manual is crucial.