1991 Bronco Fuel Pump Relay

[1991Bronco]

I'm the original owner of a 1991 Bronco that "died" on me a few years back. When it "died", it basically just quit running; and, I could smell the odor of burned electrical wire. Recently, I've decided to try and "nurse" the Bronco back to health.

The first problem I've encountered is getting power out of the fuel pump relay and to the fuel pump. I've jumpered the connections on the relay receptacle and got the pump to operate; so, I know it's not the pump.

I've also verified the relay works by using test jumpers to connect it directly to the battery then verifying continuity between pin 37 (battery; yellow wire) and pin 238 (power to inertia switch/fuel pump; dark green wire with yellow stripe). I can also hear the relay "make".

Next, I checked the conditions at the relay receptacle. I have 12V all the time at pin 37 (battery; yellow wire). With the ignition switch on, I have 12V at pin 361 (EEC module; red wire) and ground at pin 926 (EEC module; light blue wire with orange stripe). However, with all these conditions met, I still don't have 12V at pin 238 (power to inertia switch/fuel pump; dark green wire with yellow stripe). Having said that, with the relay installed, I can jumper from the negative post on the battery to pin 926 (EEC module; light blue wire with orange stripe) and get the fuel pump to operate.

So, my question deals with the method I'm using for verifying a ground condition at pin 926. With the ignition switch in the on position, I'm checking for continuity between the negative post on the battery and pin 926; and, as mentioned above, achieving continutity. However, I assume I should be using another ground reference instead of the battery post, especially since I can jumper from the battery post and get the fuel pump to operate. Correct?

Any advice would be appreciated.

Thanks!

 

[Rons beast]

According to my wiring diagram, (meager Haynes) the inertia switch gets it's power from the fuelpump relay via the drk green/yellow wire. So your tests should be correct, and the problem is no ground to the relay. There are many ground attachment points on the chassis and under the dash. You can search and check all these, as bad grounds are a common bug on Broncs. However a ground is a ground, and I may be inclined to just give the relay a ground and let it do it's job.

Good Luck and let us know how things turn out.

 

[Seabronc]

/fuel pump; dark green wire with yellow stripe). I can also hear the relay "make".

Next, I checked the conditions at the relay receptacle. I have 12V all the time at pin 37 (battery; yellow wire). With the ignition switch on, I have 12V at pin 361 (EEC module; red wire) and ground at pin 926 (EEC module; light blue wire with orange stripe). However, with all these conditions met, I still don't have 12V at pin 238 (power to inertia switch/fuel pump; dark green wire with yellow stripe). Having said that, with the relay installed, I can jumper from the negative post on the battery to pin 926 (EEC module; light blue wire with orange stripe) and get the fuel pump to operate.

the ground connection for the relay is controlled by the EEC which turns the relay on and off as needed. If you bypass that by manually grounding the relay pick coil, pin 926 you should get 12V at the output of the relay DG/Y. Did you check for 12V right at the relay? There is a connector between the relay and the inertia switch, C202, which is the connector that many of the wires use to pass through the fire wall. You may want to check for corrosion on the pins of that connector. It has been known to cause problems before.

Good luck,