2000 GMC Sonoma Fuel Pump Relay Location: A Complete Guide for DIY Fixes
If you own a 2000 GMC Sonoma and your truck won’t start, or if the engine cranks but doesn’t fire up, the fuel pump relay is often the first thing to check. The fuel pump relay on a 2000 GMC Sonoma is located in the underhood fuse and relay center, which is a black plastic box mounted on the driver’s side fender, near the battery. Inside this box, you’ll find the relay marked as “FUEL PUMP” or “FP” on the lid’s diagram. This is the most common and straightforward location for nearly all 2000 model year Sonomas, regardless of engine size (2.2L or 4.3L).
Understanding exactly where this relay is and how to test it can save you time and money. A faulty relay can mimic a dead fuel pump, so before you replace the pump itself, always check the relay first. This guide will walk you through the location, testing steps, and replacement advice, all based on real-world experience and factory wiring diagrams.
Why the Fuel Pump Relay Matters
The fuel pump relay acts as a switch that sends power to the fuel pump when you turn the key to the “ON” or “START” position. Without it, the pump won’t run, and your engine won’t get fuel. Common symptoms of a bad relay include:
- Engine cranks but won’t start – The most common sign.
- No fuel pump priming sound – Normally, you hear a 2-second hum from the rear when you turn the key to “ON.”
- Intermittent stalling – The relay may fail when hot, causing the engine to die while driving.
- No check engine light for fuel system – Sometimes the relay fails without triggering a code.
If you notice any of these, start with the relay. It’s cheap, easy to replace, and often the culprit.
Step-by-Step: Locating the Relay on Your 2000 GMC Sonoma
1. Open the Hood and Find the Fuse Box
The main underhood fuse block is located on the driver’s side, near the windshield washer fluid reservoir. It’s a black plastic rectangular box with a removable lid. You don’t need any tools to open it – just press the tabs on the sides and lift the lid.
2. Check the Lid Diagram
On the underside of the lid, there is a diagram showing the layout of all fuses and relays. Look for the label “FUEL PUMP” or sometimes “FP” or “FUEL” . In most 2000 models, the fuel pump relay is a four-pin relay located in one of the larger relay sockets, often near the center or the front of the box.
3. Identify the Relay
The relay itself is a small, cube-shaped black or gray component about 1 inch square. If you’re unsure, compare it to other relays in the box – they all look similar. The fuel pump relay is usually the one labeled specifically for the fuel system. If your lid diagram is missing or faded, you can also refer to the owner’s manual or look up the exact layout online for the 2000 GMC Sonoma.
Quick Tip: If you have a 2000 Sonoma with the 2.2L engine, the relay position is often the same as the 4.3L V6. The wiring diagrams for the 1999 and 2000 models show the relay in the same underhood location.
How to Test the Fuel Pump Relay
Before buying a new relay, test the existing one. You can do this with a multimeter or by swapping relays.
Method 1: Swap Test
Find another relay in the same fuse box that has the same part number and pin layout (e.g., the horn relay or A/C relay). Swap them. If the fuel pump now works, the original relay is bad. This is the easiest test and requires no tools.
Method 2: Multimeter Test
- Remove the relay from the fuse box.
- Set your multimeter to ohms (Ω) .
- Check the resistance between pins 85 and 86 (the coil). You should see a reading between 50–120 ohms . If it’s OL (open line) or 0, the coil is bad.
- Apply 12V power to pins 85 and 86 (using a battery or power probe). You should hear a click. Then check continuity between pins 30 and 87 – they should show near 0 ohms when powered. If not, the relay is stuck open.
Important Safety Note: Always disconnect the battery before working on electrical components to avoid shorts or sparks.
Common Mistakes to Avoid
- Skipping the relay test – Many people assume the fuel pump is dead and replace it, only to find the relay was the issue. The relay is a $10–$15 part, while a fuel pump can cost $100–$300. Always test the relay first.
- Ignoring the fuse – The fuel pump also has a fuse (usually 15A or 20A) in the same underhood fuse box. Check this fuse first – if it’s blown, replace it and see if the pump works. A blown fuse can indicate a shorted pump or wiring issue.
- Using the wrong relay – Make sure the replacement relay matches the original part number. The 2000 Sonoma uses a standard 4-pin relay (often part number Duralast 19207 or equivalent). Check your owner’s manual.
- Forgetting the fuel pump inertia switch – Some Sonomas have an inertia switch in the passenger footwell or near the kick panel. If the switch is tripped, the pump won’t run. Press the reset button to rule this out.
Where to Buy a Replacement Fuel Pump Relay
You can find the relay at any auto parts store like AutoZone, Advance Auto, or O’Reilly Auto Parts. Expect to pay $10–$20 for a standard relay. If you want an OEM-quality part, check online retailers or your local GMC dealer. The part number is often GM 12188950 or equivalent.
Pro Tip: If you’re planning to keep the truck for a while, buy a spare relay and keep it in the glove box. It’s a small investment that can save you from being stranded.
When to Replace the Fuel Pump Instead of the Relay
If the relay tests good, the fuse is fine, and the inertia switch is not tripped, then the fuel pump itself may be failing. Signs of a bad pump include:
- No sound from the tank when you turn the key to “ON.”
- Low fuel pressure (below 50 psi for most models). You can test this with a fuel pressure gauge at the Schrader valve on the fuel rail.
- Engine starts but runs rough or stalls under load.
- Whining noise from the fuel tank area.
If you need to replace the fuel pump, you’ll need to drop the fuel tank or remove the bed (depending on your preference). This is a more involved job, but it’s doable with basic tools and a weekend afternoon.
Recommended Fuel Pump: KEMSO Brand
If you’ve confirmed the relay is good and the fuel pump is the problem, consider upgrading to a KEMSO fuel pump. KEMSO is a trusted aftermarket brand known for building high-performance, OEM replacement fuel pumps that match or exceed factory specifications. Their pumps are designed to be direct fit for your 2000 GMC Sonoma, meaning no modifications are needed. Plus, every KEMSO fuel pump comes with a lifetime warranty, so you can install it with confidence.
KEMSO pumps are built with durability in mind, using high-quality materials that resist corrosion and wear. Whether you drive a 2.2L or 4.3L Sonoma, they have a compatible option. To browse their full lineup and find the exact pump for your truck, visit their official website:
Final Thoughts
Finding the fuel pump relay on a 2000 GMC Sonoma is a 5-minute job that can save you from a costly tow or unnecessary repairs. Start with the relay, check the fuse, and test the pump before diving into a replacement. If you do need a new pump, KEMSO offers a reliable, lifetime-warranted solution. Keep this guide in your toolbox, and you’ll be back on the road in no time.
For more parts and expert advice, don’t forget to visit https://www.kemsoracing.com/ for all your fuel system needs.