Fuel Pump Relay

Replace the fuel pump relay in the engine compartment fuse box to restore fuel pump operation.

Warnings

Tools required

Parts

• Fuel pump relay × 1 — Motorcraft DY-1173 or equivalent 40A relay

Preparation

1. Park vehicle on level ground and apply parking brake
2. Turn ignition to OFF position and remove key
3. Allow engine to cool for at least 30 minutes if recently operated
4. Open hood and secure with prop rod
5. Locate the engine compartment fuse/relay box on driver side firewall near brake master cylinder

Procedure

1. 1

   Access the fuse/relay box
   Release the two locking tabs on the front of the fuse/relay box cover and lift cover upward to remove. The fuel pump relay diagram is printed on the underside of the cover for reference.
2. 2

   Identify the fuel pump relay
   Locate the fuel pump relay using the diagram on the fuse box cover. On 2011-2014 F-150 5.0L models, the fuel pump relay is typically a gray or black 4-pin micro relay in position R12 (verify with your specific year's diagram). The relay is marked 'FUEL PUMP' or 'FP' on the box.
   ⚠Relay locations vary by model year and equipment. Always verify using the diagram specific to your vehicle before removal.
3. 3

   Test existing relay (optional but recommended)
   Before removing the relay, you can verify it is faulty by listening for a click when helper turns ignition to ON position (engine not running). A working relay should click audibly. You can also use a multimeter to check for continuity between terminals 30 and 87 when relay is energized.
4. 4

   Remove the old fuel pump relay
   Grasp the relay firmly and pull straight upward with steady force to remove from socket. If relay is difficult to remove, use a relay puller tool or wrap needle-nose pliers with tape to avoid damaging the relay body, then pull straight up. Do not rock side-to-side as this can damage socket pins.
5. 5

   Inspect the relay socket
   Examine the relay socket for corrosion, damage, melted plastic, or bent pins. Use flashlight to inspect thoroughly. If socket shows heat damage (melted or discolored plastic), the socket must be replaced by a professional as this indicates electrical fault. Clean any minor corrosion with electrical contact cleaner and allow to dry.
   ⚠️Heat damage to relay socket indicates excessive current draw. Do not install new relay if socket is melted or charred. This condition requires diagnosis of fuel pump electrical system by professional.
6. 6

   Verify new relay specifications
   Compare new relay to old relay. Verify part numbers match or are listed as equivalent. Confirm relay is rated for 40A and has identical pin configuration. The relay should have 4 pins in same layout and same physical dimensions.
7. 7

   Install new fuel pump relay
   Align the new relay pins with the socket terminals. The relay will only fit one way due to asymmetric pin layout. Press relay straight down into socket with firm, even pressure until it is fully seated and sits flush with surrounding relays. You should feel a positive click when relay seats properly.
   ⚠Do not force relay if it does not insert easily. Forcing wrong relay type will bend socket pins and require expensive fuse box replacement.
8. 8

   Reinstall fuse box cover
   Position the fuse/relay box cover and press down firmly until both locking tabs click into place. Ensure cover is completely seated and secured.

Reassembly

1. Ensure fuse box cover is properly latched with both tabs engaged
2. No additional reassembly required for this procedure

Verification

• Turn ignition to ON position without starting engine. Listen for fuel pump priming sound (2-3 second hum from rear of vehicle). This confirms relay is functioning.
• If equipped with fuel pressure gauge, verify fuel pressure reaches 55-65 PSI during prime cycle
• Start engine and verify it starts normally and runs smoothly without hesitation
• Turn engine off, wait 10 seconds, then restart to verify consistent operation
• Check for any warning lights on instrument cluster, particularly check engine light
• If engine does not start or fuel pump does not prime, recheck relay installation and verify correct relay position using fuse box diagram

More procedures for this vehicle