1999 Chevy Blazer Fuel Pump Reset Switch: Location, Reset, and Troubleshooting Guide

If your 1999 Chevy Blazer suddenly died or won’t start, pressing the fuel pump reset switch might be the immediate solution you need. This crucial safety device, often called an inertia switch, cuts power to the fuel pump during impacts or significant jolts to prevent fire. Finding it and knowing how to reset it correctly could save you a costly trip to the mechanic.

Your 1999 Chevy Blazer's fuel pump reset switch is a vital safety feature designed to shut off the fuel pump during a collision or severe jolt, minimizing the risk of fuel-fed fire. Often located behind the front passenger-side kick panel near the floor, its primary purpose is safety, not routine troubleshooting. Pressing the reset button firmly is a quick fix if the switch was tripped due to an impact or bump.

Understanding the Fuel Pump Reset Switch

The fuel pump reset switch, technically known as the Fuel Pump Shut-Off Switch or Inertia Switch, is an electrical safety component. It contains a sensitive internal mechanism that detects sudden, sharp changes in vehicle momentum – like those experienced during an accident or even hitting a severe pothole or curb very hard. When triggered, this mechanism physically opens the electrical circuit powering the fuel pump. This immediately stops fuel from being pumped from the tank to the engine, significantly reducing the chance of fuel leakage feeding a fire after a crash.

It's important to understand that this switch is not part of the Blazer's normal diagnostic system for fuel pump problems. Its sole job is safety. While it can be accidentally tripped by rough driving conditions or bumps (explaining why your Blazer might mysteriously die after hitting a bad bump), most instances of fuel pump failure are unrelated to this switch. The reset button provides a way to restore normal operation only if the switch itself was the cause of the fuel pump losing power.

Precise Location of the Reset Switch in the 1999 Blazer

Locating the switch is the critical first step. For the 1999 Chevrolet Blazer (and its sibling GMC Jimmy), the fuel pump reset switch is consistently found:

  1. Position: On the passenger side of the vehicle.
  2. Area: Behind the kick panel trim, positioned vertically between the lower edge of the dashboard and the door sill/floor.
  3. Installation: Mounted near the front passenger-side footwell area, attached either to the firewall or the inner kick panel frame itself.

To access it:

  1. Open the Passenger Door: This gives you necessary room.
  2. Locate the Kick Panel: This is the rigid, usually carpeted or plastic-covered panel directly below the glove box area, running vertically beside the passenger's feet. It connects the lower dash to the floor/rocker panel.
  3. Feel for the Switch: Remove the kick panel by finding its retaining clips or screws. Typically, one or two plastic push clips hold it near the top and/or bottom. Carefully pry these clips out using a flat-head screwdriver or trim tool, then pull the panel straight away or slightly towards the rear of the vehicle to release it. Once the kick panel is off, look or feel for a small, rectangular (roughly 2" x 1.5"), usually black or white, plastic module mounted vertically with a prominent rubber or plastic button on top. It will have two electrical wires connected to it.

(Insert detailed photo showing the kick panel removal and the switch location here)

Step-by-Step Guide to Resetting the Fuel Pump Switch

Resetting the switch is straightforward, but safety is paramount:

  1. Ensure Safe Conditions: Place the vehicle in Park (automatic) or Neutral with the parking brake firmly set (manual). The ignition must be completely OFF (key removed). Do not smoke or have any open flames nearby.
  2. Locate & Access the Switch: Follow the location steps above to remove the kick panel and find the switch.
  3. Firmly Press the Reset Button: Locate the button on top of the switch housing. Using your finger or thumb, press it straight down firmly and decisively until it clicks or you feel it bottom out. You do not need to hold it down. One firm press is sufficient to reset the internal mechanism. There is usually no visible indication on the switch itself (like a light) confirming the reset. The "confirmation" is if the engine starts afterward.
  4. Reinstall the Kick Panel: Carefully snap the kick panel back into place, ensuring all clips engage securely.
  5. Test the Vehicle: Turn the ignition key to the "On" (Run) position (not Start). You should hear the fuel pump run for approximately 2 seconds as it primes the system (a distinct humming/buzzing sound near the fuel tank under the rear of the vehicle). If you hear this, try starting the engine immediately afterward. If it starts and runs normally, the reset was successful, and the switch was likely the culprit.

When Resetting the Switch Doesn't Work: Troubleshooting

If you press the reset button firmly and still don't hear the fuel pump prime or the engine fails to start, the problem lies elsewhere. The switch reset only fixes the issue if the switch itself was triggered. Here are the more likely causes and next diagnostic steps:

  1. Blown Fuel Pump Fuse: This is the most common cause after a tripped inertia switch. The fuel pump circuit has its own fuse.

    • Locate: Find the primary underhood fuse box (driver's side, near the battery/bulkhead on the 1999 Blazer).
    • Identify: Check the diagram on the fuse box lid. Locate the fuse labeled "FUEL PUMP," "FP," "ECM B," or "INJ." It's typically a 20-amp mini or standard blade fuse.
    • Check: Remove the fuse carefully and inspect the thin metal strip inside the clear plastic housing. A break in the metal strip indicates it's blown. (Insert photo of good vs. blown fuse for fuel pump circuit)
    • Replace: Use an exact amperage replacement (e.g., 20A). Using a fuse with a higher amperage rating creates a serious fire hazard.

  2. Faulty Fuel Pump Relay: This relay acts as a switch, sending high current from the battery to the fuel pump when commanded by the Powertrain Control Module (PCM).

    • Locate: Also in the underhood fuse box. Find the relay labeled "FUEL PUMP," "FP," "ECM," or sometimes "A/C" (shared socket on some models - check diagram).
    • Test: The quickest test is "swapping." Identify another relay in the box with the exact same part number/pin layout (e.g., the Horn relay is often identical). Swap the suspect Fuel Pump relay with the known good one (like the Horn relay). Test the horn first to ensure that relay was good. If the horn works but stops after the swap, and the Blazer starts after swapping, you've confirmed the original Fuel Pump relay was faulty. Replace it. If swapping doesn't help, the relay might not be the issue (or both could be bad, but unlikely). More advanced testing involves powering and grounding the relay coil terminals to listen for clicks and checking continuity on the switched contacts.

  3. Electrical Wiring Fault: Damage, corrosion, or broken wires between the battery, ignition switch, fuse/relay box, inertia switch, and fuel pump itself can interrupt power. Look for chafed wires (especially near sharp metal edges), damaged connectors (brittle plastic, melted pins, green corrosion), or loose connections at the inertia switch, fuel pump relay socket, or fuel tank wiring harness connector. Pay special attention to the harness section that runs from the frame near the rear axle up to the fuel pump. Jiggling harnesses near the inertia switch or fuel tank while an assistant turns the key to "RUN" (listening for the pump to buzz) can sometimes reveal an intermittent connection.

  4. Fuel Pump Failure: If fuses and relays are good, the inertia switch is reset, and wiring checks out, the fuel pump itself is likely the problem. As these pumps age (a 1999 Blazer is over 20 years old), failure is common. Symptoms often include:

    • Engine cranks but won't start (no fuel pressure).
    • Sudden loss of power/engine dieing while driving, especially under load (often preceded by intermittent sputtering/stalling).
    • Loud whining or humming noise from the fuel tank area indicating the pump is straining.
    • In some cases, the pump may only work intermittently when hot. Diagnosing definitively requires checking fuel pressure at the Schrader valve on the fuel injector rail near the engine using a pressure gauge. Low or zero pressure with a good fuse/relay/inertia switch points strongly to pump failure. Replacement requires lowering the fuel tank.

(Insert a diagnostic flowchart image: "No Start after Reset? Check: Fuse -> Relay -> Wiring -> Fuel Pump")

Important Warnings and Safety Precautions

  • NO JUMPER WIRES: Never attempt to "jump" or bypass the inertia switch wiring to test the fuel pump. This completely defeats the critical safety function designed to prevent fire after an impact. It is dangerous and irresponsible. The switch is designed to be reset easily and safely – use it correctly.
  • Gasoline is Flammable: Be extremely cautious when working around fuel systems. No sparks, flames, or cigarettes. Working outdoors or in a well-ventilated area is best. Have a Class B fire extinguisher readily available.
  • Respect Pressure: Before disconnecting any fuel line (like for pressure testing), you must safely relieve residual fuel pressure. While the fuel rail test port has a Schrader valve for checking pressure, disconnecting lines requires depressurization. Refer to a service manual for the safest method for your year, usually involving pulling the fuel pump relay and running the engine until it stalls.
  • Battery Safety: Always disconnect the negative battery terminal before performing significant electrical work, especially near fuel lines or the pump itself, to prevent accidental sparks. Reconnect it last.
  • Verify Tripping: If the switch trips easily or repeatedly without a plausible cause (like hitting a minor bump), thoroughly inspect the switch mounting and wiring harness for looseness, vibration, or damage that might cause false triggers. Replace the switch if suspected faulty. A constantly tripping switch indicates an underlying issue needing correction.

Beyond the Reset: Maintaining Your Blazer's Fuel System

While the reset switch provides a simple fix when it trips, preventing problems and addressing root causes is key for your aging SUV:

  1. Address Root Causes of Tripping: If the switch tripped due to hitting a large pothole or curb, get your suspension and steering components checked for damage (tie rods, ball joints, control arms). Loose mounting of the switch itself can also cause false trips – ensure it's firmly secured to its bracket.
  2. Fuel Level Matters: Always try to keep your fuel tank at least 1/4 full. The fuel pump is immersed in gasoline, which cools and lubricates it. Running frequently on very low fuel causes the pump to overheat and wear out prematurely. This is a leading cause of fuel pump failure.
  3. Recognize Early Signs of Pump Failure: Pay attention to symptoms like:
    • Difficulty starting, especially the first start of the day.
    • Engine hesitates or stumbles briefly under acceleration.
    • Loss of power, particularly when climbing hills or carrying a load.
    • Intermittent stalling that gets progressively worse.
    • Unusually loud whining or buzzing noise from the fuel tank area.
    • Surging at highway speeds.
    • Don't wait for complete failure – addressing a weak pump can prevent a tow truck bill.
  4. Regular Fuel Filter Changes: The fuel filter traps debris before it reaches the injectors. A clogged filter forces the pump to work much harder, leading to early failure. Follow the service interval for replacement (often 15,000-30,000 miles, but check your manual). On the 1999 Blazer, the filter is typically located along the frame rail, driver's side, ahead of the rear axle.
  5. Fuel Quality: While modern pumps handle common gasoline, consistently using reputable stations with clean tanks reduces the chance of water or excessive debris entering your system and causing pump or injector issues. Using a fuel system cleaner periodically might help with minor deposits but won't revive a failing pump.

Key Takeaways

The 1999 Chevy Blazer's fuel pump reset switch is a critical safety device easily found behind the passenger kick panel. Firmly pressing its reset button is the immediate remedy only if it was tripped by an impact or jolt. If the engine starts immediately after resetting, the switch was the cause. However, persistent no-start or prime issues overwhelmingly point to more common problems: a blown fuel pump fuse, a faulty fuel pump relay, wiring faults, or ultimately, the dreaded fuel pump failure itself. Diagnostic steps should always follow a logical path: Reset Switch -> Fuse -> Relay -> Wiring -> Fuel Pump. Prioritize safety, respect the flammability of gasoline, and never bypass the inertia switch. Understanding this system empowers you to troubleshoot effectively and keep your veteran Blazer running safely. For fuel pump replacement or complex wiring issues, consulting a qualified mechanic is recommended.

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