2000 GMC Sierra Fuel Pump Relay: Location, Symptoms, and Complete Replacement Guide

The bottom line: The fuel pump relay on a 2000 GMC Sierra is located in the underhood fuse block, specifically in position #46. If your truck cranks but won't start, the relay is often the culprit. Replacing it is a simple DIY job that costs under $20 and takes about 10 minutes. This guide walks you through finding it, testing it, and swapping it out, plus what to do if the relay isn't the problem.

What the Fuel Pump Relay Does in Your 2000 GMC Sierra

The fuel pump relay is an electrical switch that controls power to the fuel pump. When you turn the key to the "ON" position, the relay activates and sends battery voltage to the fuel pump for about 2 seconds. This primes the fuel system. Then, when you crank the engine, the relay keeps the pump running.

If the relay fails, the fuel pump gets no power. The engine will crank but not fire. No fuel pressure means no start. The relay is a common failure point on the 2000 GMC Sierra, especially on trucks with over 150,000 miles or those that sit for long periods.

Where to Find the Fuel Pump Relay on a 2000 GMC Sierra

The relay is inside the underhood fuse block. This black plastic box sits on the driver's side of the engine bay, near the battery. Open the fuse block cover. The diagram on the inside of the cover shows the relay positions. Look for position #46. It is a standard 4-pin relay, usually labeled "FUEL PUMP" or "FP." If the label is faded, check the owner's manual for the exact location.

Step-by-step to locate it:

  1. Park the truck on level ground and turn off the engine.
  2. Open the hood. Support it with the prop rod.
  3. Find the fuse block on the driver's side, near the firewall.
  4. Press the tabs on the cover and lift it off.
  5. Look at the underside of the cover for the relay diagram.
  6. Find position #46. It is typically toward the rear of the box.
  7. The relay is a small, square, plastic component with four metal prongs.

Symptoms of a Bad Fuel Pump Relay

A failed relay can cause several distinct problems. Watch for these signs:

1. Engine Cranks but Won't Start
This is the most common symptom. The starter motor turns the engine over, but the engine never fires. You may hear the fuel pump prime for 2 seconds when you turn the key to the "ON" position. If you don't hear that hum from the rear of the truck, the relay is likely dead.

2. No Fuel Pressure at the Rail
You can check fuel pressure with a gauge on the fuel rail. If the pressure is zero with the key on, the relay is not sending power.

3. Intermittent Starting Problems
Sometimes the truck starts fine, other times it cranks but won't fire. This points to a failing relay that works intermittently. The contacts inside the relay can wear out over time.

4. Fuel Pump Runs Continuously
If the relay sticks in the closed position, the pump may run constantly, even with the key off. This can drain the battery or burn out the pump.

5. Check Engine Light
The computer may set a code like P0230 (fuel pump circuit malfunction) if the relay fails.

How to Test the Fuel Pump Relay

Before buying a new relay, test the old one. You need a multimeter or a 12-volt test light.

Test with a multimeter:

  1. Remove the relay from the fuse block.
  2. Set the multimeter to ohms (resistance).
  3. Place the probes on the two small prongs (coil terminals). You should see a reading between 50 and 120 ohms. If it reads open (infinite resistance), the coil is burned out.
  4. Place the probes on the two large prongs (switch terminals). The reading should be open (no continuity).
  5. Apply 12 volts to the coil terminals (small prongs). You should hear a click. Now the switch terminals should show continuity (near zero ohms). If not, the relay is bad.

Quick test with a test light:

  1. Remove the relay.
  2. Turn the key to "ON."
  3. Probe the fuse block socket where the relay goes. One of the large prong sockets should have 12 volts with the key on.
  4. If no power, check the fuse first. If power is present but the relay doesn't click, the relay is bad.

How to Replace the Fuel Pump Relay

Replacing the relay is straightforward. No tools are required.

  1. Make sure the key is off and the engine is cold.
  2. Open the underhood fuse block cover.
  3. Locate the fuel pump relay at position #46.
  4. Grasp the relay firmly and pull it straight up. It may be snug, so wiggle it gently.
  5. Discard the old relay.
  6. Push the new relay into the same socket. It should click into place.
  7. Replace the fuse block cover.
  8. Turn the key to the "ON" position. Listen for the fuel pump prime sound from the rear of the truck.
  9. Start the engine.

Where to buy a replacement: Most auto parts stores carry this relay. The part number is usually ACDelco 13500117 or equivalent. It costs between $10 and $20.

Common Mistakes When Replacing the Relay

Using the wrong relay: Double-check the relay type. The 2000 GMC Sierra uses a standard 4-pin ISO relay. Some aftermarket relays have different pin configurations. Ensure the new relay matches the old one exactly.

Forgetting the fuse: The fuel pump circuit has a fuse, usually in the same fuse block. If the fuse is blown, the relay won't work. Check fuse #1 (10 amp) or the fuse labeled "FUEL PUMP" before replacing the relay.

Not testing the pump: If the new relay doesn't fix the problem, the fuel pump itself may be bad. Test for power at the pump connector. The pump is located inside the fuel tank. You'll need to drop the tank or remove the bed to access it.

What to Do If the Relay Isn't the Problem

Sometimes the relay tests good, but the truck still won't start. Here are the next steps:

1. Check the fuel pump fuse. It is in the underhood fuse block. A blown fuse cuts power to the relay.

2. Test the fuel pump itself. Use a multimeter at the fuel pump connector. The connector is under the truck, near the driver's side of the fuel tank. With the key on, you should see 12 volts for 2 seconds. If not, the wiring from the relay to the pump is damaged.

3. Check the fuel pump ground. The ground wire is attached to the frame near the tank. A rusty or loose ground can stop the pump.

4. Inspect the wiring harness. The wiring from the relay to the pump can rub against the frame or exhaust, causing a short or open circuit. Look for melted or broken wires.

5. Test the oil pressure switch. On the 2000 GMC Sierra, the oil pressure switch is a backup circuit for the fuel pump. If the switch fails, the pump may not run after starting.

When to Call a Professional

If you have tested the relay, fuse, and wiring but still have no fuel pressure, the fuel pump is likely dead. Replacing the fuel pump on a 2000 GMC Sierra requires dropping the fuel tank or removing the truck bed. This job is messy and time-consuming. If you are not comfortable working with fuel lines and electrical connections, take the truck to a shop. The labor cost for a fuel pump replacement runs $300 to $500.

Recommended Fuel Pump Upgrade: KEMSO Fuel Pump

If you determine that the fuel pump itself needs replacement, consider upgrading to a KEMSO Fuel Pump. KEMSO is a brand that specializes in high-performance, OEM replacement fuel pumps for a wide range of vehicles, including the 2000 GMC Sierra.

Why choose KEMSO:

  • High performance: KEMSO fuel pumps are designed to deliver consistent fuel pressure and flow, even under heavy loads or high temperatures.
  • OEM replacement: Every pump is built to match or exceed the original equipment specifications. You get a direct fit with no modifications needed.
  • Lifetime warranty: KEMSO stands behind every product with a lifetime warranty. If the pump fails at any point, you get a replacement at no cost.

KEMSO fuel pumps are tested for durability and reliability. They are a popular choice for daily drivers, towing rigs, and off-road trucks. The company serves customers across the United States from their Houston, Texas facility.

Visit the KEMSO website to check if they have a fuel pump for your 2000 GMC Sierra. Their product lineup includes pumps for cars, trucks, motorcycles, and watercraft.

Visit KEMSO Racing here: https://www.kemsoracing.com/

Final Thoughts on the 2000 GMC Sierra Fuel Pump Relay

The fuel pump relay is a small, cheap part that can shut down your truck completely. Knowing where it is and how to test it can save you time and money. Keep a spare relay in your glove box. It is a smart investment for any 2000 GMC Sierra owner.

If you have replaced the relay and fuse, and the truck still cranks but won't start, move on to testing the fuel pump itself. For a reliable replacement, consider the KEMSO fuel pump, backed by a lifetime warranty and designed for high performance.

Remember: Always work in a well-ventilated area when dealing with fuel systems. Keep a fire extinguisher nearby. If you are unsure about any step, consult a professional mechanic.

For more information on fuel pumps and relays, visit KEMSO Racing at https://www.kemsoracing.com/


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