Where is the fuel pump relay on a 1990 Chevy Suburban 1500?
The fuel pump relay in a 1990 Suburban 1500 is located in the under-hood fuse/relay center on the passenger side of the engine bay, typically labeled FUEL PUMP.
Where the relay is usually located
In most GMT400 Suburbans of this era, the fuel pump relay lives in the large under-hood fuse/relay center mounted on the passenger-side inner fender near the firewall. The diagram or lid should identify a relay labeled FUEL PUMP (often abbreviated F-PUMP).
What you’ll be looking at is a rectangular relay with four or five terminals, nestled among other fuses and relays.
- Open the hood and locate the under-hood fuse/relay block on the passenger-side inner fender near the firewall.
- Remove the cover to view the fuse/relay map and locate the relay labeled FUEL PUMP (F-PUMP).
- Note the relay’s orientation and the terminal numbers so you can identify the coil and switched contacts.
- If your truck has a different configuration or you can’t find a FUEL PUMP label, check the diagram printed on the underside of the block lid or refer to the service manual for your exact engine code.
The diagram on the fuse block should help you confirm the exact position of the FUEL PUMP relay.
Testing the fuel pump relay
Once you’ve located the relay, you can perform basic checks to verify whether it’s functioning and feeding power to the fuel pump.
- With the ignition ON (engine off), remove the relay and inspect for corrosion or physical damage.
- Using a multimeter or test light, confirm that the coil terminals (usually 85 and 86) have 12V when the ignition is ON.
- Reinstall the relay and listen for a distinct click when power is applied; no click can indicate a faulty coil or contacts.
- Swap the FUEL PUMP relay with another identical GM relay in the same fuse block (for example, the horn or A/C relay) to see if the fuel pump operates.
- Check the fuse feeding the fuel pump circuit and inspect the wiring from the relay to the fuel pump connector in the tank for damage or loose connections.
If the relay tests indicate it’s good but the pump still doesn’t run, the problem may lie elsewhere in the fuel system, such as the in-tank pump, wiring, or the PCM control signal.
Additional notes
Always disconnect the battery before swapping relays or working near electrical connections to avoid shorts or shocks. If you’re unsure, taking photos of the fuse block and consulting a factory wiring diagram for your exact VIN can help prevent mix-ups.
Summary
For a 1990 Chevy Suburban 1500, the fuel pump relay is typically located in the under-hood fuse/relay center on the passenger side of the engine bay, labeled FUEL PUMP. Use the block’s diagram to confirm the exact location, test for voltage on the coil with ignition on, and swap with a known-good GM relay to diagnose issues. If problems persist, inspect the fuel pump, wiring, and related fuses or PCM signals.
