2002 Ford Expedition Fuel Pump Relay: Symptoms, Location, Testing, and Replacement Guide

The fuel pump relay in your 2002 Ford Expedition is a critical, inexpensive component that controls power to the fuel pump. If this relay fails, your Expedition will crank but not start. Recognizing the symptoms, knowing its location, learning how to test it, and understanding replacement are essential for resolving this common starting problem quickly and affordably.

A relay is a remote-controlled switch. It allows a small electrical current from your Expedition's Powertrain Control Module (PCM), the main computer, to activate a much larger current needed to run the fuel pump. The fuel pump relay sits in the power distribution box under your hood, acting as the gatekeeper for electrical power flowing to the fuel pump located inside the fuel tank.

Understanding Symptoms of a Bad Fuel Pump Relay (2002 Ford Expedition)

Identifying a failing or failed fuel pump relay is the first step. While some symptoms overlap with a bad fuel pump, ignition switch, or blown fuse, these signs strongly point towards the relay:

  1. Engine Cranks But Won't Start: This is the most classic symptom. You turn the key, the starter motor spins the engine, but the engine never fires up because the fuel pump isn't receiving power to deliver fuel to the engine.
  2. Intermittent Starting Problems: The vehicle might start fine one day, then refuse to start the next, or it might stall unexpectedly while driving and then restart after sitting for a while. This erratic behavior often indicates relay contacts that are worn or burnt, failing to make a consistent connection.
  3. Sudden Stalling While Driving: A relay that fails completely while the engine is running will instantly cut power to the fuel pump. This causes the engine to stall immediately without warning, just as if you had turned the ignition off.
  4. No Audible Fuel Pump Prime Noise: When you turn the ignition to the "ON" position (without cranking), you should hear a faint humming or whining sound for 2-3 seconds from the rear of the vehicle. This is the fuel pump pressurizing the system. No sound at all during this key-on phase suggests either a failed fuel pump or a lack of power reaching it (fuse, relay, or wiring).
  5. Check Engine Light (CEL) May or May Not Illuminate: The PCM primarily monitors the output of the fuel pump relay circuit (if it detects the commanded state). While a completely failed relay might trigger a code (like P0230 - Fuel Pump Primary Circuit), a weak or intermittently failing relay often does not set a specific code because the PCM doesn't always sense the intermittent connection failure.

Precisely Locating the Fuel Pump Relay in Your 2002 Expedition

For the 2002 model year, the fuel pump relay is located in the underhood Power Distribution Box (PDB). This is a large, usually black plastic box near the battery or on the driver's side fender.

  1. Open the Hood: Securely prop the hood open.
  2. Find the Power Distribution Box (PDB): Look for the large box, typically rectangular, near the battery or driver's side fender wall.
  3. Remove the PDB Cover: The cover usually clips on. Unsnap the clips and lift the cover straight off. Set it aside safely.
  4. Identify the Relay: Once the cover is off, you'll see an array of relays and fuses. On the underside of the PDB cover, there is a detailed diagram listing each relay's function and location within the box. Locate the diagram.
  5. Match the Diagram: Find the relay specifically labeled "Fuel Pump", "Fuel Pump Relay", or sometimes "FP" on this diagram. This diagram corresponds to the slots inside the PDB. The diagram will show a numbered grid or a specific location picture.
  6. Locate the Slot in the PDB: Using the diagram, find the exact slot number or position labeled for the fuel pump relay.
  7. Identify the Relay Itself: Relays in the 2002 Expedition PDB are typically standard automotive micro ISO relays. They are small, cube-shaped plastic components, often black or gray, with electrical terminals sticking out the bottom into the socket. Most will have a schematic diagram printed on the side. Standard relays have 4 or 5 terminals. The fuel pump relay slot holds a standard 4 or 5-pin mini relay.

Testing the 2002 Ford Expedition Fuel Pump Relay

Once you've located the relay, testing it is straightforward and requires minimal tools. You have three practical methods:

  1. The Swap Test (Simplest Method):

    • Turn the ignition OFF.
    • Identify the fuel pump relay and another relay in the PDB that is identical to it (same size, same number of pins). Common candidates are the horn relay or the A/C compressor clutch relay (check the diagram on the PDB cover to confirm the relay type). Do not use a relay controlling something critical or dangerous.
    • Carefully pull the known identical relay straight up and out of its socket. Pull the suspected fuel pump relay out of its socket.
    • Install the known good relay into the fuel pump relay socket. Push it down firmly until fully seated.
    • Turn the ignition key to the "ON" position (do not crank). Listen carefully near the rear of the truck for the 2-3 second fuel pump prime hum.
    • If you now hear the pump prime, and the vehicle starts when you try to crank it, the original fuel pump relay was faulty.
    • If there is still no pump prime sound and the truck still doesn't start, the issue likely lies elsewhere (fuel pump, fuse, wiring, PCM command issue).

  2. Listen/Feel Test (Requires Assistant):

    • Locate the fuel pump relay in the PDB.
    • Have an assistant turn the ignition key to the "ON" position.
    • Place your fingers gently on the relay body. You should feel and hear a distinct "click" inside the relay as it energizes when the key is turned "ON".
    • Have the assistant turn the key back to "OFF". You should feel and hear another "click" as the relay de-energizes.
    • No click at all when turning the key to "ON" strongly suggests a faulty relay, a blown fuse, or a lack of control signal from the PCM. Repeating the test while swapping a known good relay (like the horn relay) can confirm.

  3. Multimeter Voltage Test (Most Precise):

    • Caution: Ensure the ignition key is in the "OFF" position before starting. Wear safety glasses.
    • Tools: Basic digital multimeter.
    • Locate the fuel pump relay socket in the PDB (remove the relay first).
    • Refer to the relay schematic printed on the suspect relay or a standard ISO mini relay diagram. The pins are:
      • 85 and 86: Control circuit coil (low amperage).
      • 30: Constant Battery Power (from the battery fuse). Heavy gauge wire.
      • 87: Output to the Fuel Pump (only when relay is energized). Heavy gauge wire.
      • 87a: (If present) Not used in a fuel pump application.
    • Testing Power Feed (Pin 30): Set multimeter to DC Volts (20V range or auto-ranging). Clip the black meter lead to a good chassis ground. Touch the red probe to the socket terminal corresponding to Pin 30. With the key OFF, you should read battery voltage (approx. 12.6V). If not, check the main battery fuse supplying the PDB.
    • Testing Control Circuit Power (Key ON, Pin 85/86): Turn ignition to "ON". Touch red probe to Pin 86 (on Ford, this is often the PCM control side). Black lead grounded. You should see very close to battery voltage. Touch red probe to Pin 85. Black lead grounded. You should see ground (near 0 volts). This indicates the PCM is grounding the coil circuit correctly. If no power on Pin 86 (key ON), check the PCM power fuse or ignition switch circuit. If no ground on Pin 85 (key ON), suspect PCM issue or wiring fault.
    • Testing Relay Operation & Output (Pin 87): Reinsert the relay into its socket.
    • Set multimeter to DC Volts. Connect black lead to chassis ground.
    • Carefully backprobe the wire attached to terminal Pin 87 (output to pump). You may need to access it near the relay socket. Be gentle, do not short the probe.
    • Have an assistant turn the ignition to "ON".
    • The multimeter should read battery voltage for 2-3 seconds and then drop to 0 volts. This confirms the relay is closing properly when commanded and sending power to the pump circuit.
    • No voltage on Pin 87 with the key ON despite seeing power on Pin 30 and correct control signals on 85/86 indicates a faulty relay.

Purchasing a Replacement Relay for a 2002 Ford Expedition

After confirming the relay is faulty, replacing it is inexpensive and simple.

  1. OEM (Original Equipment Manufacturer) Part Number: The genuine Ford relay part number for the 2002 Expedition fuel pump relay is often F57B-14B192-AA, F7PB-14B192-AA, or DY-1149. Using an OEM part guarantees compatibility.
  2. Aftermarket Options: Numerous reputable aftermarket brands offer compatible relays (BWD, Standard Motor Products (SMP), Duralast, Bosch). A Standard ISO mini relay matching the original pin configuration (4 or 5 pin) and rated current (typically 20A-30A) is suitable. Common aftermarket numbers include:
    • Standard Motor Products (SMP) RY-149
    • BWD R3172
    • Duralast F1337
    • Bosch 0332019150
  3. Stores: Relays are readily available at Ford dealership parts departments, major auto parts stores (AutoZone, O'Reilly Auto Parts, Advance Auto Parts, NAPA), and online retailers (Amazon, RockAuto).

Step-by-Step Replacement Procedure

Replacement takes only a few minutes:

  1. Park Safely & Turn Off: Park the Expedition on a level surface. Engage the parking brake firmly. Turn the ignition OFF and remove the key from the ignition cylinder.
  2. Open Hood: Lift and secure the hood safely.
  3. Disconnect Battery (Safety Step): Highly Recommended. Disconnect the NEGATIVE (-) battery cable first. Isolate it away from the battery terminal. This prevents accidental shorts or sparks near the PDB. While relays can usually be swapped hot, disconnecting the battery is the safest practice.
  4. Locate PDB & Fuel Pump Relay: Follow the location steps outlined earlier to find the specific relay socket.
  5. Remove Old Relay: Firmly grasp the old relay with your fingers. Pull it straight upwards out of its socket. It may require a moderate tug. Do not twist or rock it excessively.
  6. Prepare New Relay: Inspect the terminals on the new relay. Ensure they are clean and undamaged. Compare it to the old relay to confirm identical terminal arrangement.
  7. Install New Relay: Align the new relay's terminals with the slots in the socket. Push it down firmly and evenly until it seats completely with a definite "click" or snug fit. Ensure it is oriented correctly based on the terminal layout (should match the old relay's position and the socket).
  8. Reconnect Battery: Reconnect the negative battery cable and tighten the clamp securely.
  9. Test Operation: Turn the ignition key to the "ON" position (do not crank). Listen carefully near the rear of the truck for the 2-3 second fuel pump prime hum. If you hear it, that's a good sign. Now attempt to start the engine. It should start normally.

Troubleshooting Tips if Problems Persist

If replacing the relay doesn't solve the no-start issue:

  1. Inspect Fuses: Locate the fuse for the fuel pump circuit. For the 2002 Expedition, this is often Fuse # F1.27 (30A) in the Passenger Compartment Fuse Panel (left side of dash, behind the access panel) and possibly a maxi-fuse (like F2.3 - 50A) in the Power Distribution Box under the hood. Check the diagram on the PDB cover and the interior fuse panel cover. Pull suspect fuses and visually inspect the metal element inside the clear plastic window for a break. Use your multimeter on the continuity setting. Replace any blown fuse with one of the identical amperage rating. Important: Investigate why the fuse blew (short circuit) before concluding the repair.
  2. Confirm Fuel Pump: With a known good relay installed, listen for the pump prime sound. No sound strongly points towards a failed fuel pump, a break in wiring to the pump (including the inertia shutoff switch), or a PCM control problem preventing relay activation. Testing fuel pressure at the engine rail schrader valve is the definitive mechanical test for pump operation.
  3. Check Inertia Switch: The Expedition has a fuel pump inertia shutoff switch located on the front passenger side kick panel (low down near the firewall/carpet area). It trips during impact to cut fuel pump power. Its button may pop up. Ensure this button is fully pushed down. Press it firmly to reset it. It can also fail internally.
  4. Inspect Wiring: Visually inspect wiring going to the fuel pump relay socket, the pump itself, and between the PCM and the relay for obvious damage, chafing, corrosion, or disconnected connectors (particularly at the PCM). Check wiring grounds. A broken wire or corroded connector can interrupt power flow just like a bad relay.
  5. PCM Signal: While rare, a problem with the PCM's ability to ground the relay control circuit (Pin 85) will prevent the relay from energizing even if the relay itself is good. This requires professional diagnostics with a scan tool capable of commanding the fuel pump relay on.

Final Thoughts: Addressing Relay Issues for Reliable Starts

The fuel pump relay is a small but vital part of your 2002 Ford Expedition's fuel delivery system. When it fails, the truck cranks but doesn't start. Recognizing the symptoms – primarily an engine that cranks normally but refuses to start, often with no fuel pump prime noise – is key. Locating the relay in the underhood Power Distribution Box using the diagram is straightforward. Simple tests like swapping in a known good relay, listening/feeling for clicks, or a basic voltage test can usually confirm relay failure within minutes. Replacement involves pulling the old relay out and pushing a new, inexpensive compatible relay into the socket. Ensuring you hear the fuel pump prime after replacement provides immediate confirmation. Always check associated fuses, particularly the fuel pump fuse in the interior panel, and consider the inertia switch reset if the problem persists after relay replacement. For most owners, replacing a faulty fuel pump relay is a quick, cost-effective DIY repair that restores reliable starting to your Expedition.

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