Signal


#1

86 Ford , 302. Where does the signal come from that tells the fuel pump relay to send power to the fuel pump?


#2

The ECM. But, it goes through an ‘impact detector’ that is like a circuit breaker, only a sharp hit will make it pop. This is a small black box behind the seats that has a white reset button on top.


#3

Initially from the battery, through the ignition switch and the emergency cut-off switch (also known as the inertia switch, meant to shut off fuel flow in case of a crash). There is a fuse in the circuit, somewhere, too.

Start at the beginning, and follow the circuit. A service manual (Haynes or Ford factory) would probably help quite a bit. Try Books4Cars.com for an inexpensive used manual.