Early Bronco Fuel Pump & Relay Wiring
IF THE IMAGE IS TOO SMALL, click it.
Most of the first (Left) panel of the diagram applies to all eBs. All the new FP wiring is near the bottom. The main power comes from a ring terminal on the starter relay; the trigger comes from a splice in circuit 904 (anywhere, including at the I terminal on the ig.sw.); the trigger ground must be continuous back to the battery (-) post (like all grounds). Each of the other 3 panels only applies to trucks whose owners choose the particular fuel pump setup described. So ignore the 2 that don't apply to YOUR eB.
There are several sources for both types of fuel valve, including
O'Reilly AP, &
BC Broncos. The FSV-2A kit includes a generic toggle switch, but the stock eB tank select switch is easy to rewire for either valve.
Bosch/Tyco/ISO 30A cube relays are common & cheap.
The inertia (impact/crash/rollover) switch is inexpensive & easy-to-find at junkyards, and only
~$80 new (XF3Z9341AA), but a
knock-off can be had for ~$40. If not from a JY, the pigtail is
~$12 (Pico 5756PT). It's worth it to make sure the fuel pump doesn't set the truck on fire after a wreck or rollover; particularly on vehicles without an EEC/PCM to turn off the FP relay when the engine stops.
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For dual EFI, note that connectors 235 & 236 are the same gender, so they don't fit together. Either the connectors can be cut off & their wires spliced, or an intermediate connector can be used.
The small fuel valve has ~20 Ohms, so it draws ~0.7 A continuously when directing flow to its top port. It draws nothing (off) when the bottom port is active. The large valve draws slightly more, but ONLY while it's changing positions. Once the switch is made, it holds there mechanically, and draws no current in either position.
The transfer pump is risky because it's easy to cause big problems. There must be provisions NOT SHOWN in this diagram to prevent the transfer pump from running when the aux. tank is empty (damaging the pump), OR from running when the main tank is full (causing fuel to overflow) UNLESS the overflow is directed back to the aux. tank (which solves both problems, until the main tank stops overflowing).
