* Under the hood in the fuse/relay center: This is the most common location. The fuse/relay center is usually located near the battery, often on the driver's side fender well. Consult your owner's manual or a wiring diagram to identify the specific relay. The relay itself may be labeled, or you might need to use a multimeter to test relays to find the one for the fuel pump.
* Inside the cab, under the dash: Less common, but possible on some models. This is usually near the fuse panel under the dash. Again, a wiring diagram or owner's manual will be crucial.
To find it definitively:
1. Consult your owner's manual: This is the best place to start. It will have a diagram showing the location of all fuses and relays.
2. Use a wiring diagram: A wiring diagram specific to your 1991 Chevy pickup's year, model, and engine will precisely show the fuel pump relay's location and its connections. You can find these online (often for a fee) or at auto parts stores.
3. Look for markings: Once you've located the fuse/relay boxes, carefully examine the relays. Some may have labels indicating their function.
4. Use a multimeter: If you can't find a label, a multimeter can help identify the correct relay by testing the circuit for the fuel pump. Caution: Work with the battery disconnected to avoid electrical shock.
Remember to always disconnect the negative battery terminal before working with electrical components to prevent shorts and injury.
