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Looking for help with Wiring at the Fuel Pump Relay by nero
Started on: 10-30-2019 07:53 PM
Replies: 9 (186 views)
Last post by: nero on 11-16-2019 06:06 PM
nero
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Report this Post10-30-2019 07:53 PM Click Here to See the Profile for neroClick Here to Email neroSend a Private Message to neroEdit/Delete MessageReply w/QuoteDirect Link to This Post
Hi, I am looking for some help from any wiring experts on a wire I found spliced into the tan / white wire going into the fuel pump relay. Pictures and details are below.

Below is where a black wire is spliced into the tan / white wire at the fuel pump relay.



Below is the other end of the black wire which is so very neatly.....wrapped around the positive side of the ignition coil.


Below is the wiring diagram at the fuel pump relay. From what I can tell it looks like the black wire was spliced into the tan / white wire to get power and bypass the fuel pump relay. From what I see the tan / white wire goes from the relay to the fuel pump (along with some other locations). So from here I am thinking it was either bypassed because the relay was bad, or there is a break in the wire from the fuse panel to the fuel pump relay, or the fuel pump fuse was blown at some point and they wired it this way to get it running. I Just want to see if I am on the correct track in terms of tracing down why this was done so I can get the original issue fixed.
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olejoedad
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Report this Post10-31-2019 12:09 AM Click Here to See the Profile for olejoedadClick Here to Email olejoedadSend a Private Message to olejoedadEdit/Delete MessageReply w/QuoteDirect Link to This Post
I agree with your assessment.
The black wire effectively bypasses the FPR.
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Blacktree
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Report this Post10-31-2019 01:14 AM Click Here to See the Profile for BlacktreeClick Here to visit Blacktree's HomePageClick Here to Email BlacktreeSend a Private Message to BlacktreeEdit/Delete MessageReply w/QuoteDirect Link to This Post
Looks like somebody wanted the fuel pump to run whenever the ignition is hot. It also looks like that somebody was a hack (in my opinion).

Personally, I would get rid of that black wire. It wasn't installed properly, anyway. And if it's there to bypass a bad relay, you can just replace the relay.
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nero
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Report this Post10-31-2019 05:04 AM Click Here to See the Profile for neroClick Here to Email neroSend a Private Message to neroEdit/Delete MessageReply w/QuoteDirect Link to This Post
Thanks Olejoedad and Blacktree.

I am in 'assesment' mode right now as I just picked the Fiero up a few weeks ago so just figuring out what previous owners have done to the car. As you mentioned Blacktree, someone along the way was a hack. I am hoping this is the only 'fix' that the previous hack made. Not even sure how that wire managed to stay on the coil (I drove it for 90 min to get home) as it was not even under the screw, it was just wrapped around the screw and fell off when my neighbor touched the wire.

I am going to put the battery back in tonight and then do a few more tests to confirm if it was just a bad relay. I will update with what I find.

Thanks again.
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Francis T
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Report this Post10-31-2019 09:40 AM Click Here to See the Profile for Francis TClick Here to visit Francis T's HomePageClick Here to Email Francis TSend a Private Message to Francis TEdit/Delete MessageReply w/QuoteDirect Link to This Post
Smart move, for sure, you do want to get rid of that bypass wire! The last thing you'd want is a fuel pump running when the engine is not, like after a crash! Hopefully that hacker did not do other wacky nods.
Good luck with the car.
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nero
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Report this Post11-02-2019 05:38 PM Click Here to See the Profile for neroClick Here to Email neroSend a Private Message to neroEdit/Delete MessageReply w/QuoteDirect Link to This Post
So,I took out the splice and got the wiring fixed up. I tested the existing relay off the car and seemd fine but picked up a new one just in case. I tried it out today and the fuel pump does not turn on. The relay does not engage. I verified I have power going to the relay, it seems its not receiving the signal from the ecm to close the relay. So I am going to have to track that back to see if its wiring or the ecm.
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nero
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Report this Post11-03-2019 04:01 PM Click Here to See the Profile for neroClick Here to Email neroSend a Private Message to neroEdit/Delete MessageReply w/QuoteDirect Link to This Post
I ran through all the tests outlined in the service manual to test out the fuel pump and all associated wiring. It has all lead back to a bad ECM. So I am now on the hunt for an ECM. I did find the ground wire belwo that was broken off which I temporarily attached until I can get the proper eyelet connector but that did not correct the issue either.

I see lots of places to get an ECM from, are there any suggestions on where to pick one up?

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nero
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Report this Post11-16-2019 04:29 PM Click Here to See the Profile for neroClick Here to Email neroSend a Private Message to neroEdit/Delete MessageReply w/QuoteDirect Link to This Post
I ended up ordered an ECM from Rock Auto. I swapped the Prom over from the existing ECM, hooked everthing back up and the fuel pump now works as it should.
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fierosound
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Report this Post11-16-2019 05:04 PM Click Here to See the Profile for fierosoundClick Here to visit fierosound's HomePageClick Here to Email fierosoundSend a Private Message to fierosoundEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by nero:

I ran through all the tests outlined in the service manual to test out the fuel pump and all associated wiring. It has all lead back to a bad ECM.



 
quote
Originally posted by nero:

I ended up ordered an ECM from Rock Auto. I swapped the Prom over from the existing ECM, hooked everything back up and the fuel pump now works as it should.





I keep telling the guys that the diagnostic charts in the Factory Service Manual do work.

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nero
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Report this Post11-16-2019 06:06 PM Click Here to See the Profile for neroClick Here to Email neroSend a Private Message to neroEdit/Delete MessageReply w/QuoteDirect Link to This Post
Yep, I was actually surprised as I have had mixed results trying to work through the flow charts in past projects, but following through the fuel pump flow chart from the factory service manual actually made perfect sense to me and I am by far no expert with tracing back wires / electrical.
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