What does the inertia fuel shutoff switch do on the 4.9L Bronco and F-Series?

It is a safety device that cuts off power to the electric fuel pump if a collision occurs; it opens on impact and must be reset manually. It receives 12V on circuit 238 (DG/Y wire) through connector C271.

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

Circuit 787, a pink/black (PK/BK) wire, carries 12V from the inertia fuel shutoff through connector C441 to the fuel pump/fuel gauge sender.

What are the fuel gauge sender resistance values?

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

How is the F-Series dual tank fuel system wired?

Power on circuit 670 (R/Y) goes through connector C268 to the fuel tank selector switch (page 49-2). The switch sends 12V on circuit 786 (R) via C440 to the front tank pump/sender or on circuit 789 (BR/W) via C205 and C441 to the rear tank pump/sender.

Where do the fuel pump circuits ground?

Both pumps ground on circuit 89 (O) to splice S400, then circuit 57 (BK) to ground G100. Ground details are on page 10-2 for F-Series and page 10-5 for Bronco.

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Ford Bronco & F-Series 4.9L Fuel Pump Wiring Diagram - Inertia Switch, Sender

Ford 23-7 Engine Controls 4.9L wiring diagram with inertia fuel shutoff, fuel pumps and fuel gauge sender

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Engine controls wiring diagram for 4.9L showing inertia fuel shutoff, fuel tank pumps and fuel gauge sender circuits for F-Series and Bronco.

AI caption August 2018 · Photo 343 of 386

This is page 23-7 of a Ford engine controls wiring diagram for the 4.9L engine, showing the fuel pump and fuel gauge sender circuits for two vehicle configurations: F-Series and Bronco. Both circuits begin at connector C202 (from page 23-1) with 12V on circuit 238 (dark green/yellow wire) feeding the inertia fuel shutoff switch via connector C271 — a safety device that cuts power to the electric fuel pump in a collision and must be reset manually. The F-Series path continues on circuit 670 (red/yellow) through connector C268 to a fuel tank selector switch (page 49-2), which routes power via circuit 786 (red) to the front tank fuel pump/gauge sender through C440, or via circuit 789 (brown/white) to the rear tank sender through C205 and C441. The Bronco path uses circuit 787 (pink/black) to a single fuel pump/fuel gauge sender via C441, with the instrument cluster (page 60-1) connected via circuit 29 (yellow/white) through C205. The sender is a variable resistor: 22.5 ohms empty, 145 ohms full. Both circuits ground on circuit 89 (orange) and 57 (black) through splice S400 to ground G100 (grounds on pages 10-2 and 10-5).

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Frequently asked questions

What does the inertia fuel shutoff switch do on the 4.9L Bronco and F-Series?: It is a safety device that cuts off power to the electric fuel pump if a collision occurs; it opens on impact and must be reset manually. It receives 12V on circuit 238 (DG/Y wire) through connector C271.
What wire color and circuit feeds the Bronco fuel pump/fuel gauge sender?: Circuit 787, a pink/black (PK/BK) wire, carries 12V from the inertia fuel shutoff through connector C441 to the fuel pump/fuel gauge sender.
What are the fuel gauge sender resistance values?: 22.5 ohms when the tank is empty and 145 ohms when full. The sender is a variable resistor connected to a float in the fuel tank.
How is the F-Series dual tank fuel system wired?: Power on circuit 670 (R/Y) goes through connector C268 to the fuel tank selector switch (page 49-2). The switch sends 12V on circuit 786 (R) via C440 to the front tank pump/sender or on circuit 789 (BR/W) via C205 and C441 to the rear tank pump/sender.
Where do the fuel pump circuits ground?: Both pumps ground on circuit 89 (O) to splice S400, then circuit 57 (BK) to ground G100. Ground details are on page 10-2 for F-Series and page 10-5 for Bronco.