No power to 85 on fuel pump relay

SHORTYDAWG

MEMBER
1993 FORD RANGER
2.3L
4 CYL
2WD
AUTOMATIC
100,000 MILES

New fuel pump ignition switch. Checked ECU at relay yellow stays hot constant black and tan is hot when ignition on. Grounds tested fine. Checked fuel pump relay 30 black and yellow to fuse is hot constant however red wire 85 with ignition on does not get hot for 2 second prime.I sprayed starter fluid in carburetor cranked over I am getting fire from coil but I'm not getting injector fire. Help

5 Replies

CARADIODOC

MECHANIC
33,864 POSTS

According to your test results, the PCM Power relay has to be defective, or there's a stretched terminal in its socket. There should be 12 volts on the red wire all the time when the ignition switch is in the "run" position. The 12 volts on the tan / black wire comes from the same place that feeds the ignition coils. That's the ignition switch. That's why you have spark, and it shows the PCM Power relay should be on when the ignition switch is on, not just for two seconds. It's the fuel pump relay that gets turned on for two seconds, then again during cranking.

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Tuesday, November 24th, 2020 AT 8:14 AM

SHORTYDAWG

MEMBER
41 POSTS

Okay, so my PCM relay tested hot constantly on yellow wire black and tan is hot when ignition on so your saying it's com relay itself and if it's a stretched socket/bad wire is on PCM side so check there the fuel pump relay is fine even though red 85 does not get hot because of PCM relay or bad wire.

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Tuesday, November 24th, 2020 AT 8:14 AM

CARADIODOC

MECHANIC
33,864 POSTS

If the turn-on signal is on the tan / black wire and the ground is good, that relay has to be bad or a terminal isn't making good contact.

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Tuesday, November 24th, 2020 AT 8:14 AM

SHORTYDAWG

MEMBER
41 POSTS

Thanks. It has gotten dark on me I will check again for bad connection. I have 3 relays and swapped out still same thing. Is it possible all relays are bad? I've been fighting this thing for months. I could have possibly burned all three up didn't think the odds all three are bad. I'll get back on it tomorrow and let you know what I find. Thanks so much I really need help with this truck, lol.

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Tuesday, November 24th, 2020 AT 8:14 AM

KEN L

MASTER CERTIFIED MECHANIC
47,320 POSTS

I have seen bad fuel pump or grounds take out the relays. can you please check the connections and wiring? Please use this guide and the fuel pump wiring diagrams above:

https://www.2carpros.com/articles/how-to-check-wiring

Please let us know what you find. We are interested to see what it is.