No power to fuel pump relay

[A1Stack]

Hey guys, I have an 87 Bronco II that I purchased in non running condition. No power to fuel pumps. I was able to get them to kick on by jumping the 2 relay connectors, so I can rule out bad pumps and any wiring issues further back. I ran a voltage test on the relay plug, I’m getting the correct power and grounds on all the pins except for the pin that I believe is supposed to power on with the ignition turned on. I had my wife crank the engine while I checked for voltage, nothing. Anybody else had this problem? Could it be the ignition switch, or maybe a bad computer?

 

[telnex]

Hey guys, I have an 87 Bronco II that I purchased in non running condition. No power to fuel pumps. I was able to get them to kick on by jumping the 2 relay connectors, so I can rule out bad pumps and any wiring issues further back. I ran a voltage test on the relay plug, I’m getting the correct power and grounds on all the pins except for the pin that I believe is supposed to power on with the ignition turned on. I had my wife crank the engine while I checked for voltage, nothing. Anybody else had this problem? Could it be the ignition switch, or maybe a bad computer?

check your fuel cutoff / inertia switch. mine was bad and I had to bypass it.

 

[A1Stack]

check your fuel cutoff / inertia switch. mine was bad and I had to bypass it.

That was one of the first things I checked, hoping that was it but intertia switch is good. No power before intertia switch. I have some diagnostic ideas, just haven’t had time to get out there. I believe I either have a bad ground going to computer or just a bad computer

 

[tw205]

Test the relay first by applying a ground to the fuel pump test port on the ecm diagnostic connection. If the pumps turn on then the fuel system works. If not check for power at the relay. Relay should have two power sources. 1 always hot BK/Y, 2 key on hot R. The ECU supplies the ground LB/O, closing the circuit, triggering the relay sending the always hot thru the relay to the inertia switch DG/Y and pumps.

 

[A1Stack]

Test the relay first by applying a ground to the fuel pump test port on the ecm diagnostic connection. If the pumps turn on then the fuel system works. If not check for power at the relay. Relay should have two power sources. 1 always hot BK/Y, 2 key on hot R. The ECU supplies the ground LB/O, closing the circuit, triggering the relay sending the always hot thru the relay to the inertia switch DG/Y and pumps.

I’m going to get a new battery next weekend, and will try this and report back! Thank you