New on ClubRX - Rewire your fuel pump! Easy, cheap, reliability mod!
The red wire in my photo above was added by me. The wire to cut is the large blue one which is coming out of the harness and goes into the bottom of the fuel pump relay. You can see in the photo, that I left about 1 to 1-1/2 inches of the big blue wire coming out of the harness. Subsequently I insulated that and taped it back to the harness. But you should remove the fuel pump fuse from the joint box which is located under the drivers side kick panel (US cars, not sure about JDM and others). Once that fuse is pulled, then the big blue wire coming out of that harness is DEAD.
So you need to supply fused power to the large blue wire going INTO the relay. The fuse ought to be 20 amps as that is the size of the oem fuse (located in the joint box as described above). You can actually use that 20 amp fuse in one of the empty fuse slots, but you need to give it power. My photo shows how I used the existing power tap (one of two large black unswitched positive wires inside that box) to power the fuse. All I had to add was a female spade connector to receive the other side of the 20 amp fuse and connect THAT to the big blue wire. You could solder and tape the connection, but as shown in my photo, I used bullet connectors. If you want to run a whole new wire from the battery with a separate fuse holder and a 20 amp fuse, go for it. It is the same thing.
Clear?
-- James
So you need to supply fused power to the large blue wire going INTO the relay. The fuse ought to be 20 amps as that is the size of the oem fuse (located in the joint box as described above). You can actually use that 20 amp fuse in one of the empty fuse slots, but you need to give it power. My photo shows how I used the existing power tap (one of two large black unswitched positive wires inside that box) to power the fuse. All I had to add was a female spade connector to receive the other side of the 20 amp fuse and connect THAT to the big blue wire. You could solder and tape the connection, but as shown in my photo, I used bullet connectors. If you want to run a whole new wire from the battery with a separate fuse holder and a 20 amp fuse, go for it. It is the same thing.
Clear?
-- James
I know this thread is overdone but here's a tip just to simplify. You don't even need the red wire, just stick a sharp object (a pic) into the factory zip tie and undo it. You can now pull the electrical tape back further and cut the blue wire 3 or 4 inches further down.
Magnet Boy
Joined: Jan 2007
Posts: 251
Likes: 1
From: NorCal
I know this thread is overdone but here's a tip just to simplify. You don't even need the red wire, just stick a sharp object (a pic) into the factory zip tie and undo it. You can now pull the electrical tape back further and cut the blue wire 3 or 4 inches further down.
Glug Glug Glug Burp
Joined: Jan 2002
Posts: 3,819
Likes: 0
From: Scott AFB, IL
Hopefully all you guys raving about this 'mod' are also doing more important reliability mods on a 13+ year old car IE: injector cleaning, fuel filter replacement etc.
While there is no real harm in doing this mod, it's not going to keep together an old car that isn't properly cared for in the first place.
While there is no real harm in doing this mod, it's not going to keep together an old car that isn't properly cared for in the first place.
Glug Glug Glug Burp
Joined: Jan 2002
Posts: 3,819
Likes: 0
From: Scott AFB, IL
C'mon fellas... search. 
One:
https://www.rx7club.com/showthread.p...wire+fuel+pump
More:
https://www.rx7club.com/showthread.p...wire+fuel+pump
https://www.rx7club.com/3rd-generation-specific-1993-2002-16/more-proof-fuel-pump-rewire-improves-fuel-pressure-565645/
http://www.stealth316.com/2-fuelpumpguide.htm
One:
https://www.rx7club.com/showthread.p...wire+fuel+pump
More:
https://www.rx7club.com/showthread.p...wire+fuel+pump
https://www.rx7club.com/3rd-generation-specific-1993-2002-16/more-proof-fuel-pump-rewire-improves-fuel-pressure-565645/
http://www.stealth316.com/2-fuelpumpguide.htm
Here is how I rewire my pump, it's a bit different then this one, but effective and simple. Even simpler for relocated batteries.
You will need enough 10G wire to go from your battery to the fuel pump area, a short 10G wire for the new ground. Some light gauge wire to power the relay, a bosch or bosch style 20-40 amp relay, and a fuse holder w/ fuse. Follow the diagram for instructions.
You will need enough 10G wire to go from your battery to the fuel pump area, a short 10G wire for the new ground. Some light gauge wire to power the relay, a bosch or bosch style 20-40 amp relay, and a fuse holder w/ fuse. Follow the diagram for instructions.
After reading the thread several times and getting a good understanding of the steps involved im happy with the results! Sorry no data to back up the voltage increase but the procedures explained in this thread where very helpful. (Thanks GADD and Dubulup) What i did notice is that my AFR at idle increaced from low 11s to the mid 12s. I have 850s in the primaries and have the power fc and walbro (sp?) in the tank. I have been tying to get the idle to lean out for a long time with no luck. Tried the negative lag and all that. It was just shocking that this simple rewire leaned out my idle!!! Whatever works im happy with the results so far!
^^Most reports are that it does richen it. I don't know, I have not done this yet myself b/c my idle is already far too rich and I do not need it any worse. Fuel pressure seems to be just fine with my setup so I am not in any hurry to do this.
that is odd that it would go leaner, especially if the low speed resistor was bypassed. The only thing I could think is maybe the higher pressure, atomized the fuel better with the large injectors, which resulted in a better more complete burn. If the injectors have large droplets of fuel they will not ignite as easily and cause poor burn and result in richer mixtures. That's the only explanation I can think of.... either that or you're lying haha
Yeah I was hesitant to try this rewire too because my Afr at idle were already too rich. (didnt want it richer) I have contemplated putting the 550 back in because of the idle but i need the 850 in for boost. Anyway That was my first drive with the new rewire and it did lean the idle out. Im not saying its the answer to my problem but i will continue to log and see if my idle does stay in the mid to high 12s. I just checked and I have a Negative Lag of .18 I may even try to pull some fuel out at those idle cells and see if i cant get idle into the 13s. (Dudemaaanownsanrx7 Thanks for all your post on the forum I read them all the time and is very helpful. Hoping to get up in the boost like you have been talking about with water injection.)
correct me if im wrong but...
I did this a few years back, but did it a little differently.
Instead of running a new wire and fuse, there is a spare fuse holder in the relay box that is powered by a 10ga wire direct from the battery. Simply cut the solid blue wire powering the relay back far enough to reach the spare fuse holder and solder a spade connector to it.
I had the same voltage increase that Mr. Clark did and had the max fuel pump pressure go from 75psi on the stock wiring to 80psi.
To clarify what twokrx7 said, the power for the pump is run though the ignition switch, this is done in many cars and I supect for redundancy, and this mod bypass it.
Instead of running a new wire and fuse, there is a spare fuse holder in the relay box that is powered by a 10ga wire direct from the battery. Simply cut the solid blue wire powering the relay back far enough to reach the spare fuse holder and solder a spade connector to it.
I had the same voltage increase that Mr. Clark did and had the max fuel pump pressure go from 75psi on the stock wiring to 80psi.
To clarify what twokrx7 said, the power for the pump is run though the ignition switch, this is done in many cars and I supect for redundancy, and this mod bypass it.
I know this thread is overdone but here's a tip just to simplify. You don't even need the red wire, just stick a sharp object (a pic) into the factory zip tie and undo it. You can now pull the electrical tape back further and cut the blue wire 3 or 4 inches further down.
correct me if im wrong but after reading this thread twice already, my understanding is that the tip above mentioned by Uncle Hungry on rxcited2's method ends up going back and being the same as the initial simplified method from Gadd right?