1999 F150 Fuel Pump Relay Location: Your Quick Guide to Finding, Testing, and Replacing It

The fuel pump relay in a 1999 Ford F-150 is located in the Central Junction Box (CJB) under the hood. Specifically, look for it in Position 11 within this fuse/relay panel (for gasoline V6 and V8 engines). The CJB is positioned against the firewall on the driver's side of the engine compartment. Remove the CJB cover to access the relays and fuses; the fuel pump relay is typically black or gray and plugs into the socket labeled "11".

This relay controls power to your fuel pump. When it fails, your engine cranks but won't start. Knowing its exact spot helps quickly diagnose this common no-start issue. Accessing the relay takes minutes.

Why the Fuel Pump Relay Matters
The fuel pump relay is an electrically operated switch. Turning the ignition key sends a signal to this relay. The relay then connects high-amperage battery power directly to the fuel pump. This powers the pump to build fuel pressure for starting and running. A bad relay cuts off this power flow instantly. Symptoms include:

  • Engine cranking normally without firing
  • No audible humming from the fuel tank area when the key is turned to "ON"
  • Sudden engine stalling while driving
  • Intermittent starting problems

Locating the Central Junction Box (CJB)
Pop the hood of your 1999 F-150. Stand facing the front of the truck. Direct your attention to the rear of the engine compartment, near the windshield (firewall), on the driver's side. This is where the Central Junction Box (CJB) is mounted. It's a black plastic box, roughly rectangular, housing fuses and relays. A textured plastic cover snaps onto it. The CJB is positioned just forward of the brake master cylinder or brake booster. No other electrical boxes match its size and location on the driver's firewall.

Identifying Position 11 Inside the CJB
Switch off the ignition before proceeding. Remove the CJB cover by releasing its plastic snap clips. Flip the cover over after removal. You'll find a detailed diagram molded into the underside matching the relay and fuse positions inside the box. Search for the listing "Fuel Pump Relay" on this diagram. Note the corresponding position number – almost always Position 11. Glance inside the open CJB. Look for numbered slots molded into the black plastic base near each socket. Find the socket assigned to position 11. This socket holds the fuel pump relay.

Recognizing the Fuel Pump Relay
The relay in Position 11 is the target. It's a standard Bosch-style automotive cube relay, roughly 1-inch square. The relay color commonly appears black or dark gray. Look for terminal pins protruding from its base. A factory part number like F7AB-14B192-AA may appear on its side, confirming its identity. Avoid confusion with similar-looking relays nearby. Other non-essential relays (e.g., horn relay, A/C relay) occupy positions like 12 or 10. Rely solely on the diagram and position label.

Safety Precautions Before Touching Relays
Electrical safety is critical. Disconnect the negative battery cable using a 10mm wrench. Secure the cable away from the battery terminal. This prevents accidental short circuits or sparks when handling the relay. Fuel system depressurization is also recommended:

  1. Disconnect the negative battery terminal.
  2. Find the fuel pump inertia shut-off switch (yellow button near passenger kick panel inside the cab). Push its reset button down.
  3. Attempt to crank the engine for 3-5 seconds. The engine won't start but residual fuel pressure discharges.
    Follow these steps to minimize fire risk or electrical damage.

Removing the Fuel Pump Relay
With the CJB cover off and the battery disconnected, removal is straightforward:

  1. Firmly grip the fuel pump relay body in Position 11. Do not pull wires.
  2. Pull straight upward. Apply even pressure until it unplugs from the socket.
  3. Avoid twisting or rocking the relay forcefully; this can damage socket terminals.
    The relay is now accessible for inspection or replacement.

Testing the 1999 F150 Fuel Pump Relay
Symptoms might point to the relay, but testing verifies its condition. Use these methods:

  • Swap Test: Identify another identical relay (standard cube type) in the CJB. The horn relay (Position 5) is often a good candidate. Swap the horn relay and the fuel pump relay. Reconnect the battery. Turn the ignition to "ON". If the fuel pump now hums (indicating power restored), your original relay is faulty. If blowing the horn works after the swap, this further confirms the swap method.

  • Multimeter Test (Continuity): Remove the relay. Set your multimeter to continuity (beep setting) or Ohms (Ί). Test pins 85 and 86: These are the relay coil terminals. There should be measurable resistance (typically 50-120 Ohms). An "OL" reading indicates an open coil. An audible continuity beep confirms the coil circuit is intact.

  • Multimeter Test (Contact Function): Set the meter to continuity. Test pins 30 and 87a (Normally Closed): You should have continuity with the relay resting. Test pins 30 and 87 (Normally Open): No continuity should exist. Apply 12 volts to pins 85 (+) and 86 (-) (use fused jumper wires or a bench battery). An audible click confirms activation. While activated, continuity should now exist between pins 30 and 87 (Normally Open). Continuity between pins 30 and 87a (Normally Closed) should disappear.

Replacing the Relay
Only use an exact replacement relay compatible with your 1999 F-150. Standard OEM part numbers are F7AB-14B192-AA or Motorcraft part RY13. Auto parts stores stock equivalents. Key specifications:

  • 12-Volt DC rating
  • 4-Pin (ISO Mini) configuration
  • Normally Open (NO) contact type
  • 30-40 Amp load capacity
    Plug the new relay directly into Position 11 socket, orienting it correctly (match the pin configuration). Ensure it snaps firmly into place.

Checking Related Fuses
Fuses protect the fuel pump circuit. Check these simultaneously:

  • CJB Fuse #13 (30A): Supplies primary power to the fuel pump relay contacts.
  • CJB Fuse #2 (10A): (PCM Power) Controls the signal activating the fuel pump relay coil.
  • Under-Hood Power Distribution Box (PDB) Fuse #6 (Maxi-Fuse 50A): Critical for supplying power to the CJB. Find the PDB near the battery.
    Visually inspect all fuses. Replace blown ones. Use the amperage markings: Fuse #13 requires a 30A fuse; Fuse #2 requires a 10A fuse. Never install a higher-rated fuse.

Resetting the Fuel Pump Inertia Switch
Accidental bumps can trip this safety switch. Locate it on the passenger side cab interior, above the footwell carpet near the kick panel. Press the red reset button firmly down until it clicks and stays down. Try starting.

When Replacement Doesn't Solve the Problem
Diagnose further:

  • Confirm 12V at relay socket Position 11 (Terminal 87 to ground) with the ignition on.
  • Verify voltage at fuse #13 in the CJB.
  • Check voltage at the Power Distribution Box output terminals.
  • Listen for pump operation near the fuel tank.
  • Investigate wiring issues or fuel pump failure.

Final Tips
Relay replacement requires basic tools: a wrench, screwdriver. Keep a spare relay in your glove box. Familiarize yourself with the CJB diagram. Record the relay position before removal. Always disconnect the battery first. Confirm socket orientation during installation. This relay fixes many no-start occurrences quickly and affordably.

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