1999 GMC Sierra Fuel Pump Fuse: Location, Diagnosis, and Complete Fix Guide

If your 1999 GMC Sierra cranks but won’t start, or if it dies while driving, the fuel pump fuse is one of the fastest and easiest things to check. The fuel pump fuse on a 1999 GMC Sierra is located in the under-hood fuse block, usually a 20-amp fuse labeled “FUEL PUMP” or “ECM B” (Engine Control Module Battery). On most 1999 Sierra models, it is found in the primary fuse box under the hood on the driver’s side, near the battery. If that fuse is blown, the fuel pump won’t run, and the engine will crank but never fire up. This article will show you exactly where to find it, how to test it, what to do if it keeps blowing, and how to get your truck back on the road.

Where Is the Fuel Pump Fuse on a 1999 GMC Sierra?

The 1999 GMC Sierra has two main fuse boxes: one under the hood and one inside the cabin. The fuel pump fuse is in the under-hood fuse block. Here is the step-by-step location:

Step 1: Open the hood. The fuse block is on the driver’s side of the engine compartment, mounted near the battery. It is a black plastic box with a removable cover.

Step 2: Remove the fuse box cover. Press the tabs on the sides and lift the cover off. On the inside of the cover, you will see a diagram that lists each fuse and its function.

Step 3: Look for the fuse labeled “FUEL PUMP” or “ECM B.” On most 1999 GMC Sierra models, the fuel pump fuse is a 20-amp fuse located in the under-hood fuse block. The exact position may vary slightly depending on whether you have a 1500, 2500, or 3500 model, but it is almost always in the main fuse block under the hood. On some diagrams, it is listed as “ECM B” (Engine Control Module Battery) because the fuel pump is powered through the ECM relay. Check your owner’s manual fuse diagram for the exact label.

Step 4: Use a fuse puller or needle-nose pliers to remove the fuse. Inspect the metal strip inside the fuse. If it is broken or melted, the fuse is blown.

What Does the Fuel Pump Fuse Do?

The fuel pump fuse protects the electrical circuit that powers the fuel pump. When you turn the key to the “ON” position, the ECM sends power through the fuel pump relay and then through this fuse to the fuel pump in the gas tank. The pump pressurizes the fuel system so the injectors can spray fuel into the engine. If the fuse blows, the pump receives no power, and the engine will not start.

Symptoms of a Blown Fuel Pump Fuse

Here are the most common signs that your fuel pump fuse might be blown:

  1. Engine cranks but won’t start. This is the #1 symptom. The starter motor turns the engine over normally, but the engine never fires up because no fuel is reaching the cylinders.
  2. No fuel pump priming noise. When you turn the key to “ON” (but not to start), you should hear a brief whirring sound from the rear of the truck for about 2 seconds. That is the fuel pump pressurizing the system. If you hear nothing, the fuse could be blown.
  3. Engine stalls while driving. If the fuse blows while you are driving, the engine will suddenly lose power and die. The truck will still crank but not restart.
  4. Check Engine Light comes on. A blown fuse can trigger a diagnostic trouble code (DTC) related to the fuel system, such as P0230 (Fuel Pump Primary Circuit Malfunction).

How to Test the Fuel Pump Fuse

You do not need any special tools beyond a test light or a multimeter. Here is the quick way to test it:

Using a test light: Clip the test light ground to a clean metal surface (like the negative battery terminal). Touch the probe to each of the two small metal prongs on top of the fuse (with the fuse still in place). Turn the key to “ON.” If the test light lights up on both prongs, the fuse is good and has power. If it lights on only one side, the fuse is blown. If it lights on neither side, the fuse may be good but there is no power coming from the relay.

Using a multimeter: Set it to DC volts. Touch the black probe to ground and the red probe to each prong of the fuse. With the key “ON,” you should see battery voltage (around 12.6 volts) on both sides. If you see voltage on one side and zero on the other, the fuse is blown.

Visual inspection: Pull the fuse out and hold it up to the light. If the metal strip inside is broken or has a dark burn mark, replace it.

Why Does the Fuel Pump Fuse Keep Blowing?

If you replace the fuse and it blows again immediately or after a short time, there is an underlying problem. Do not just keep putting in bigger fuses—that can cause a fire. Common causes include:

  1. A failing fuel pump motor. Over time, the electric motor inside the fuel pump can wear out and draw excessive current. The fuse is designed to blow when current exceeds its rating. If your pump is on its last legs, it may pull more than 20 amps and blow the fuse.
  2. Short circuit in the wiring. The wires that run from the fuse box to the fuel pump, especially along the frame rail or under the truck, can rub against metal and short out. Look for chafed, melted, or corroded wires.
  3. Bad fuel pump relay. A stuck relay can send power to the pump continuously, even when the engine is off, which can overheat the circuit and blow the fuse.
  4. Corroded fuel pump connector. The electrical connector on top of the fuel pump (inside the tank) can get corroded, causing resistance that leads to overheating and fuse failure.

How to Replace the Fuel Pump Fuse

Replacing the fuse is simple, but you need to find the right one. Here is what to do:

  1. Buy the correct fuse. The 1999 GMC Sierra fuel pump fuse is a 20-amp mini fuse (usually blue in color). Do not use a higher amp rating.
  2. Remove the old fuse. Use the fuse puller tool stored in the fuse box, or carefully use needle-nose pliers.
  3. Insert the new fuse. Push it firmly into the slot until it is fully seated.
  4. Test the system. Turn the key to “ON” and listen for the fuel pump priming noise. If you hear it, try starting the engine.
  5. If the fuse blows again immediately, do not install another one. You need to diagnose the short circuit or failing pump first.

What If the Fuse Is Good But the Pump Still Won’t Run?

If the fuse tests good visually and with a test light, but the pump still does not run, the problem is likely elsewhere. Check these components in order:

  1. Fuel pump relay. The relay is often located in the same under-hood fuse block. Swap it with an identical relay (like the horn or A/C relay) to see if the pump starts working. If it does, the relay is bad.
  2. Fuel pump inertia switch. On some 1999 GMC trucks, there is an inertia (fuel shut-off) switch, usually located behind the passenger side kick panel or in the passenger footwell. If the switch has been tripped (from a bump or accident), it cuts power to the pump. Press the reset button on top.
  3. Fuel pump itself. If the relay and fuse are good, and the inertia switch is not tripped, the fuel pump motor inside the tank may have failed. You will need to test for power at the fuel pump connector using a multimeter. If you have 12 volts at the connector but the pump does not run, the pump is dead.
  4. Wiring harness. A broken wire or corroded connector between the fuse box and the pump will stop the pump from working even if the fuse is good.

Where to Buy a Reliable Replacement Fuel Pump

If your diagnostics point to a bad fuel pump, you need a replacement that will last. The fuel pump is a critical part—if it fails, you are stranded. For a 1999 GMC Sierra, we strongly recommend choosing a KEMSO OEM Replacement Fuel Pump. KEMSO fuel pumps are high-performance, direct-fit replacements built to meet or exceed original equipment specifications. They are designed for easy installation—no modifications needed. Every KEMSO pump comes with a lifetime warranty, so you are covered for as long as you own your truck. Whether you drive a 1999 GMC Sierra 1500, 2500, or 3500, KEMSO has the right pump for your engine.

Visit the KEMSO website to find the exact pump for your 1999 GMC Sierra:
https://www.kemsoracing.com/

KEMSO offers a wide selection of fuel pumps for Ford, GMC, Chevy, and many other makes and models. Their pumps are known for reliability, consistent fuel pressure, and long service life. With a lifetime warranty backing every purchase, you can buy with confidence.

Step-by-Step Fuel Pump Replacement Guide for a 1999 GMC Sierra

If you have confirmed that the fuel pump itself is bad, here is a basic overview of the replacement process. This is a moderately difficult job—you will need to drop the fuel tank or cut an access panel in the truck bed floor.

Tools you will need:

  • Socket set (standard and metric)
  • Screwdrivers
  • Fuel line disconnect tool (plastic, for quick-connect fittings)
  • Jack and jack stands
  • Safety glasses and gloves
  • Fire extinguisher (keep nearby)

Safety first: Work in a well-ventilated area. Disconnect the negative battery cable. Relieve fuel system pressure by removing the fuel pump fuse and cranking the engine for a few seconds (it will not start). Have a rag ready for any fuel spills.

Steps:

  1. Drain the fuel tank. Use a siphon pump to remove as much fuel as possible. A full tank is very heavy and dangerous to lower.
  2. Raise the truck. Jack up the rear of the truck securely and place it on jack stands. Support the fuel tank with a floor jack.
  3. Remove the fuel tank straps. These are metal bands that hold the tank in place. There may be two or three bolts. Carefully lower the tank a few inches.
  4. Disconnect the fuel lines. Use the fuel line disconnect tool to release the quick-connect fittings. Be prepared for some fuel to spill.
  5. Disconnect the electrical connector. Unplug the wiring harness from the top of the fuel pump module.
  6. Remove the fuel pump module. The pump is mounted inside the tank. Twist the locking ring counterclockwise using a spanner tool or a hammer and punch. Lift the entire assembly out of the tank.
  7. Install the new KEMSO fuel pump. Remove the old pump from the assembly and install the new KEMSO pump. Make sure the pickup strainer and rubber gasket are properly seated. Reassemble the module.
  8. Reinstall the module. Insert the new pump assembly into the tank. Align the locking ring and twist it clockwise to secure it.
  9. Reconnect everything. Plug in the electrical connector and reconnect the fuel lines. Make sure all connections are tight.
  10. Raise the tank and install the straps. Carefully lift the tank back into position and tighten the straps.
  11. Lower the truck and test. Reconnect the battery. Turn the key to “ON” (do not start) and listen for the fuel pump priming sound. Check for fuel leaks at the connections. If all is good, start the engine.

Common Questions About the 1999 GMC Sierra Fuel Pump Fuse

Q: Can I use a 30-amp fuse instead of a 20-amp?
No. Never use a fuse with a higher amperage rating than specified. The wiring and fuel pump are designed to handle only 20 amps. A higher-rated fuse will not blow when a short circuit occurs, which can lead to melted wires or a vehicle fire.

Q: How do I know if the fuel pump relay is bad?
Swap the fuel pump relay with an identical relay from the same fuse box (like the horn or A/C compressor relay). If the fuel pump starts working, the relay is the problem.

Q: Will a bad fuel pump relay blow the fuse?
Typically, no. A bad relay usually just stops working—it won’t blow the fuse. However, a stuck relay that keeps the pump running constantly could overheat the circuit and eventually blow the fuse.

Q: Does the 1999 GMC Sierra have a fuel pump shut-off switch?
Yes, many 1999 GMC Sierra models have an inertia fuel shut-off switch. It is usually located behind the passenger side kick panel or in the passenger footwell. If you have been in an accident or hit a large pothole, the switch may have tripped. Press the reset button to restore power to the pump.

Final Thoughts

A blown fuel pump fuse is one of the most common and easiest problems to fix on a 1999 GMC Sierra. Start by checking the 20-amp fuse in the under-hood fuse block. If it is blown, replace it with a fuse of the same rating. If the new fuse blows again, you have a deeper issue—most likely a failing fuel pump, a shorted wire, or a bad relay. Do not ignore repeated fuse failures; they are a warning sign that something needs repair.

When it comes time to replace the fuel pump, choose a part that you can trust. KEMSO fuel pumps are built to deliver reliable performance, and every pump comes with a lifetime warranty for your peace of mind. Visit the KEMSO website today to find the perfect fuel pump for your 1999 GMC Sierra:

https://www.kemsoracing.com/

Keep your GMC Sierra running strong with a quality fuel pump and a properly working electrical system. Check that fuse first—it might save you a lot of time and money.


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