What does the inertia fuel shutoff switch do on a Ford Bronco or F-Series 5.0L?

It is a safety device that shuts off power to the electric fuel pump if a collision occurs. It opens on impact and must be reset manually.

What are the resistance values of the Bronco fuel gauge sender?

The sender is a variable resistor connected to a float in the fuel tank: 22.5 ohms when empty (fuel low) and 145 ohms when full (fuel high).

What wire color feeds the Bronco fuel pump/fuel gauge sender?

Circuit 787 PK/BK (pink/black) carries 12V (switch closed) from the inertia fuel shutoff through connectors C205 and C441 to the fuel pump/fuel gauge sender.

How is the F-Series dual-tank fuel pump wiring routed?

Power on circuit 670 R/Y goes to the fuel tank selector switch (C268), which sends 12V on circuit 786 R to the front tank pump/sender (C440) or circuit 789 BR/W to the rear tank pump/sender (C441).

Where do the fuel pump circuits ground?

Both pumps ground through circuit 89 O to splice S400, then circuit 57 BK to ground G100 (see grounds page 10-2 for F-Series, page 10-5 for Bronco).

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Ford Bronco & F-Series 5.0L Fuel Pump Wiring Diagram - Inertia Switch, Sender

Engine Controls wiring diagram, 5.0L, page 24-8, inertia fuel shutoff and fuel pump circuits for F-Series and Bronco

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Ford 5.0L engine controls wiring diagram of inertia fuel shutoff, fuel selector and fuel pump/gauge sender circuits for F-Series and Bronco.

AI caption August 2018 · Photo 372 of 386

This is page 24-8 of a Ford wiring diagram manual titled "Engine Controls, 5.0L," showing the fuel pump and fuel gauge sender wiring for both F-Series trucks and the Bronco. Both circuits begin at connector C202 (referenced on page 24-1) via circuit 238 DG/Y through connector C271 to the Inertia Fuel Shutoff switch, a safety device that opens on impact and cuts power to the electric fuel pump; it must be reset manually. On F-Series, circuit 670 R/Y feeds a Fuel Tank Selector Switch (page 49-2) through C268, which routes 12V to either the front tank pump/sender via circuit 786 R (C440) or the rear tank pump/sender via circuit 789 BR/W (C205, C441). Grounds run through circuit 89 O to splice S400, then 57 BK to ground G100 (grounds page 10-2). On Bronco, circuit 787 PK/BK feeds a single Fuel Pump/Fuel Gauge Sender through C205 and C441, with circuit 29 Y/W tied to the Instrument Cluster (page 60-1); ground is 57 BK/89 O through S400 to G100 (grounds page 10-5). Notes explain the sender is a variable resistor: 22.5 ohms empty, 145 ohms full.

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Frequently asked questions

What does the inertia fuel shutoff switch do on a Ford Bronco or F-Series 5.0L?: It is a safety device that shuts off power to the electric fuel pump if a collision occurs. It opens on impact and must be reset manually.
What are the resistance values of the Bronco fuel gauge sender?: The sender is a variable resistor connected to a float in the fuel tank: 22.5 ohms when empty (fuel low) and 145 ohms when full (fuel high).
What wire color feeds the Bronco fuel pump/fuel gauge sender?: Circuit 787 PK/BK (pink/black) carries 12V (switch closed) from the inertia fuel shutoff through connectors C205 and C441 to the fuel pump/fuel gauge sender.
How is the F-Series dual-tank fuel pump wiring routed?: Power on circuit 670 R/Y goes to the fuel tank selector switch (C268), which sends 12V on circuit 786 R to the front tank pump/sender (C440) or circuit 789 BR/W to the rear tank pump/sender (C441).
Where do the fuel pump circuits ground?: Both pumps ground through circuit 89 O to splice S400, then circuit 57 BK to ground G100 (see grounds page 10-2 for F-Series, page 10-5 for Bronco).