What does the inertia fuel shutoff switch do on the 5.8L Bronco/F-Series?

It is a safety device that shuts off power to the electric fuel pump if a collision occurs (it opens on impact). The switch must be reset manually. It sits at connector C271 on circuit 238 DG/Y.

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

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.

What wire feeds the Bronco fuel pump?

Circuit 787 PK/BK (pink/black) runs from the inertia fuel shutoff at C271 through C205 to the Fuel Pump/Fuel Gauge Sender at C441. Ground is 57 BK through splice S400 to G100.

How does the F-Series dual-tank fuel pump wiring differ from the Bronco?

The F-Series uses a Fuel Tank Selector Switch (connector C268, circuit 670 R/Y in) that directs 12V to either the front tank pump on circuit 786 R (connector C440) or the rear tank pump on circuit 789 BR/W (connector C441). The Bronco has a single fuel pump/sender at C441.

Where do the fuel pump circuits ground?

Both pump grounds run on circuit 89 O to splice S400, then on 57 BK to ground G100. See grounds page 10-2 (F-Series) or page 10-5 (Bronco).

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Ford Bronco & F-Series 5.8L Fuel Pump Wiring Diagram - Inertia Switch, Sender

Engine Controls wiring diagram, 5.8L, page 25-6, inertia fuel shutoff and fuel pump circuits for F-Series and Bronco

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Ford 5.8L 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 378 of 386

This document is page 25-6 of a Ford factory-style wiring diagram set covering Engine Controls for the 5.8L engine. It shows the fuel pump and fuel gauge sender circuits for both F-Series trucks and the Bronco. Both circuits begin at connector C202 (from page 25-1) on circuit 238 DG/Y, passing through the Inertia Fuel Shutoff switch (a safety device that cuts power to the electric fuel pump on impact and must be reset manually) at connector C271. The F-Series version continues on circuit 670 R/Y to a Fuel Tank Selector Switch (C268, page 49-2), which routes 12V to either the front tank pump (786 R via C440) or the rear tank pump (789 BR/W via C205 and C441); both pumps ground through circuit 89 O to splice S400 and 57 BK to ground G100 (grounds page 10-2). The Bronco version uses circuit 787 PK/BK to a single combined Fuel Pump/Fuel Gauge Sender at C441, with the gauge feed 29 Y/W from the instrument cluster (page 60-1); the sender reads 22.5 ohms empty and 145 ohms full, grounding through 57 BK and 89 O to S400 and G100 (grounds page 10-5). Readers can learn wire colors, circuit numbers, connector IDs, and sender resistance specs.

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Frequently asked questions

What does the inertia fuel shutoff switch do on the 5.8L Bronco/F-Series?: It is a safety device that shuts off power to the electric fuel pump if a collision occurs (it opens on impact). The switch must be reset manually. It sits at connector C271 on circuit 238 DG/Y.
What are the fuel gauge sender resistance values for the Bronco?: 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.
What wire feeds the Bronco fuel pump?: Circuit 787 PK/BK (pink/black) runs from the inertia fuel shutoff at C271 through C205 to the Fuel Pump/Fuel Gauge Sender at C441. Ground is 57 BK through splice S400 to G100.
How does the F-Series dual-tank fuel pump wiring differ from the Bronco?: The F-Series uses a Fuel Tank Selector Switch (connector C268, circuit 670 R/Y in) that directs 12V to either the front tank pump on circuit 786 R (connector C440) or the rear tank pump on circuit 789 BR/W (connector C441). The Bronco has a single fuel pump/sender at C441.
Where do the fuel pump circuits ground?: Both pump grounds run on circuit 89 O to splice S400, then on 57 BK to ground G100. See grounds page 10-2 (F-Series) or page 10-5 (Bronco).