no power to fuel pump or inertia switch

[50mustangs]

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I have a 1997 Ford Ranger xl 2wd with 3.0 liter. bought the truck with a blown engine. had three broken connecting rods. anyway, I installed a new engine and now I find that I have zero fuel pressure and I can't hear the pump when the key is turnd on. So, I checked the interia switch (GOOD). removed my bed to get to the fuel pump and found no power at the pump. went back to interia switch to check for power (I know, I should have did that before removing the bed.. live and learn..lol) (NO POWER). when I turn the key on I can hear the relays clicking but I can't hear the pump. not sure which is the fuel pump relay but all three have the same part number printed on them so I switched them (still nothing). can somebody tell me which is the fuel pump relay and where the fuse is. I have a haynes manual but it don't tell which or where the relay or the fuse is located. I checked all fuses under dash and in the power distrubution box and they are good. I found one fusible link (not sure what it went to) and it was good. how can I test the pcm? any troubleshooting tips? thank you

 

[50mustangs]

I read a couple forums that stated that the check engine light didn't come on when the key is turned to on position indicating the pcm is not getting power. I checked mine and the check engine light doesn't come on. maybe my pcm isn't getting power. from what I've read the pcm tells the relay when to energize the fuel pump. I followed the wire with the fusible link and I found it went to something not installed by Ford prolly a cb or some kind of accessery. where can I find the fusible link? thanks

 

[Earl43P]

http://www.therangerstation.com/tech_library/EDiagrams/files/Diagram_Enginecontrols4_0_3_0_1of3.JPG

That ^^ is fairly accurate for your truck. Check the fuses and the PCM Power Diode has to be installed in the proper direction. It is in the under hood fusebox and is part of the path for power to the PCM relay. The PCM relay does route power to the fuel pump relay, as shown in that diagram. No CEL = no PCM relay energized.

 

[Psychopete]

Check the wires at the computer relay harness, make sure fused power is there, that you have key on power, and good ground. That should get you a lot closer to the problem.

 

[50mustangs]

where is the PCM power Diode?

 

[50mustangs]

FOUND IT!!!!! thanks guys the information you've provided me was very valuable and I've learned alot. two different thing were wrong. first thing was the wire at the fuel relay to the intertia switch and PCM (dark green an yellow wire) was very corroded under the distribution box. I cleaned that wire up and reinstalled. checked for power at fuel pump and I then had power. Still no noise from pump or fuel pressure. pulled pump and found wire broke. installed new pump and assembly. hit switch and heard hummmmmmm. bled air out of fuel lines. hit the starter and she fired up and purred like a kitten.