Relay between the power wire for fuel pump?
03-08-2013, 12:24 PM
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Relay between the power wire for fuel pump?
Adding this to the tech/misc forum but also have it listed in 88-91 forum.
A friend of mine bought a 91 civic hatch that has a jdm b16a and pr3 ecu.
The car wouldnt start, the kid he bought it from said it ran fine and then just wouldn't start 1 day. The kid thought it was the fuel pump got a new 1 installed it same thing.
My buddy bought it and I've been going over the wiring, some of the engine/chassis grounds were crap so we replaced them. I then checked the main relay it tested fine so I checked the harness for it and there was an issue going to the fuel pump using the jumper so I moved to the connection under the rear seat. It had power at the connector but none at the fuel pump. I noticed there was a relay installed in the power wire going to the fuel pump.
When by passing the relay the fuel pump primes like it should and runs like normal after start up, we let it idle for about 45min and everything was fine no blown fuses, error codes, etc..
My question is does the relay have to be there since the swap was done or can it be eliminated?
Im guessing it was added to keep it from blowing fuses but Im not sure as stated during idle it didnt blow any.
If it does need to be there would someone have a diagram they can provide to show how it should be hooked up?
The relay that is being used is a 5 pole 12v 20a/30a and I dont think its wired properly from what I have found online but im not sure. A jumper and a rectifier diode has been added to it and I dont know why or what they are for.
Im attaching a link to a diagram that I have drawn up representing how the relay is wired and the list of how the relay is suppose to be wired based off what I have found.
See pics below (post 3)
If any additional info is needed let me know and I'll try to provide you with what I can.
Also the relay has a ground going to it, its ran inside the sheathing with the connector but its separate from the connector, what is it suppose to be attached to?
Any info you can provide would be great. Thanks
A friend of mine bought a 91 civic hatch that has a jdm b16a and pr3 ecu.
The car wouldnt start, the kid he bought it from said it ran fine and then just wouldn't start 1 day. The kid thought it was the fuel pump got a new 1 installed it same thing.
My buddy bought it and I've been going over the wiring, some of the engine/chassis grounds were crap so we replaced them. I then checked the main relay it tested fine so I checked the harness for it and there was an issue going to the fuel pump using the jumper so I moved to the connection under the rear seat. It had power at the connector but none at the fuel pump. I noticed there was a relay installed in the power wire going to the fuel pump.
When by passing the relay the fuel pump primes like it should and runs like normal after start up, we let it idle for about 45min and everything was fine no blown fuses, error codes, etc..
My question is does the relay have to be there since the swap was done or can it be eliminated?
Im guessing it was added to keep it from blowing fuses but Im not sure as stated during idle it didnt blow any.
If it does need to be there would someone have a diagram they can provide to show how it should be hooked up?
The relay that is being used is a 5 pole 12v 20a/30a and I dont think its wired properly from what I have found online but im not sure. A jumper and a rectifier diode has been added to it and I dont know why or what they are for.
Im attaching a link to a diagram that I have drawn up representing how the relay is wired and the list of how the relay is suppose to be wired based off what I have found.
See pics below (post 3)
If any additional info is needed let me know and I'll try to provide you with what I can.
Also the relay has a ground going to it, its ran inside the sheathing with the connector but its separate from the connector, what is it suppose to be attached to?
Any info you can provide would be great. Thanks
Last edited by NoHonda4Me; 03-08-2013 at 02:54 PM. Reason: link not working
03-08-2013, 02:08 PM
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Re: Relay between the power wire for fuel pump?
Adding this to the tech/misc forum but also have it listed in 88-91 forum.
A friend of mine bought a 91 civic hatch that has a jdm b16a and pr3 ecu.
The car wouldnt start, the kid he bought it from said it ran fine and then just wouldn't start 1 day. The kid thought it was the fuel pump got a new 1 installed it same thing.
My buddy bought it and I've been going over the wiring, some of the engine/chassis grounds were crap so we replaced them. I then checked the main relay it tested fine so I checked the harness for it and there was an issue going to the fuel pump using the jumper so I moved to the connection under the rear seat. It had power at the connector but none at the fuel pump. I noticed there was a relay installed in the power wire going to the fuel pump.
When by passing the relay the fuel pump primes like it should and runs like normal after start up, we let it idle for about 45min and everything was fine no blown fuses, error codes, etc..
My question is does the relay have to be there since the swap was done or can it be eliminated?
Im guessing it was added to keep it from blowing fuses but Im not sure as stated during idle it didnt blow any.
If it does need to be there would someone have a diagram they can provide to show how it should be hooked up?
The relay that is being used is a 5 pole 12v 20a/30a and I dont think its wired properly from what I have found online but im not sure. A jumper and a rectifier diode has been added to it and I dont know why or what they are for.
Im attaching a link to a diagram that I have drawn up representing how the relay is wired and the list of how the relay is suppose to be wired based off what I have found.
HTTPS://skydrive.live.com/redir?resi...BFAEE7899A!210
If any additional info is needed let me know and I'll try to provide you with what I can.
Also the relay has a ground going to it, its ran inside the sheathing with the connector but its separate from the connector, what is it suppose to be attached to?
Any info you can provide would be great. Thanks
A friend of mine bought a 91 civic hatch that has a jdm b16a and pr3 ecu.
The car wouldnt start, the kid he bought it from said it ran fine and then just wouldn't start 1 day. The kid thought it was the fuel pump got a new 1 installed it same thing.
My buddy bought it and I've been going over the wiring, some of the engine/chassis grounds were crap so we replaced them. I then checked the main relay it tested fine so I checked the harness for it and there was an issue going to the fuel pump using the jumper so I moved to the connection under the rear seat. It had power at the connector but none at the fuel pump. I noticed there was a relay installed in the power wire going to the fuel pump.
When by passing the relay the fuel pump primes like it should and runs like normal after start up, we let it idle for about 45min and everything was fine no blown fuses, error codes, etc..
My question is does the relay have to be there since the swap was done or can it be eliminated?
Im guessing it was added to keep it from blowing fuses but Im not sure as stated during idle it didnt blow any.
If it does need to be there would someone have a diagram they can provide to show how it should be hooked up?
The relay that is being used is a 5 pole 12v 20a/30a and I dont think its wired properly from what I have found online but im not sure. A jumper and a rectifier diode has been added to it and I dont know why or what they are for.
Im attaching a link to a diagram that I have drawn up representing how the relay is wired and the list of how the relay is suppose to be wired based off what I have found.
HTTPS://skydrive.live.com/redir?resi...BFAEE7899A!210
If any additional info is needed let me know and I'll try to provide you with what I can.
Also the relay has a ground going to it, its ran inside the sheathing with the connector but its separate from the connector, what is it suppose to be attached to?
Any info you can provide would be great. Thanks
People put a relay on the fuel pump for two reasons.
1. Part of a fuel pump kill system
2. So they can run a dedicated power wire from the alt and use the stock wire to trigger the realy
03-08-2013, 02:37 PM
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Re: Relay between the power wire for fuel pump?
Sorry just seen my link wasnt working, its a picture of the diagram I had drawn of how it was wired but no there was no additional constant power to it. It was just the power wire running from the main relay to the fuel pump was split and the relay was added in it. Since its a 5 pole it should have had a constant according to wiring I found for a 5 pole relay but it wasn't wired that way. Also from what I seen the relay wasn't wired right but again its difficult to explain how it was all wired so look over the diagram and lmk if you have any idea what whoever installed it was trying to do with it. Thanks
Also this is a picture of the connector for the relay in the car
Last edited by NoHonda4Me; 03-08-2013 at 02:53 PM. Reason: link not working
03-08-2013, 03:05 PM
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Re: Relay between the power wire for fuel pump?
1 is the diagram I had drawn to explain the setup the other shows the connector as it was in the car. In the 2nd pic you can see a ground seperate that was ran to the relay but the wire looks factory and since we removed the relay the ground is longer connected to anything. Got any idea what it went to? Thanks again
03-08-2013, 05:24 PM
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Re: Relay between the power wire for fuel pump?
Looks like it was trying to be a fuel pump kill.
Is there a switch hidden anywhere or a wire from the relay to an alarm?
In any event, put the wires back to stock configuration.
http://www.civic-eg.com/causeforalar...kill/index.php
Is there a switch hidden anywhere or a wire from the relay to an alarm?
In any event, put the wires back to stock configuration.
http://www.civic-eg.com/causeforalar...kill/index.php
03-10-2013, 09:51 AM
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Re: Relay between the power wire for fuel pump?
I agree,
By the way it is wired, it is just a redundant relay...
If I am looking at this correctly the output from the PGM-FI Main Relay, [yellow/black] is connected to #30 and #86 of the relay, [supplying 12V+] #87 of relay, [normaly closed] goes to the fuel pump, so #85 must go to a switch that supplies a ground to energize the relay, ["killing" fuel pump power].
I would reconnect the yellow/black and elliminate the relay, it is a poor way to do fuel pump kill, better to just install a switch on the ground to the PGM-FI Main Relay, a small, easly hidden, 1A on/off switch is all that is needed for the low current ground. 94
By the way it is wired, it is just a redundant relay...
If I am looking at this correctly the output from the PGM-FI Main Relay, [yellow/black] is connected to #30 and #86 of the relay, [supplying 12V+] #87 of relay, [normaly closed] goes to the fuel pump, so #85 must go to a switch that supplies a ground to energize the relay, ["killing" fuel pump power].
I would reconnect the yellow/black and elliminate the relay, it is a poor way to do fuel pump kill, better to just install a switch on the ground to the PGM-FI Main Relay, a small, easly hidden, 1A on/off switch is all that is needed for the low current ground. 94
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