How to rewire your fuel pump for max efficiency!

Basic tech questions such as future setups, different turbo kits, car diagnosis, etc

How to rewire your fuel pump for max efficiency!

Postby shift_down » Thu Jul 04, 2013 6:58 pm

Most of our 240s are decades old, and it is no surprise that the wiring in our cars are worn down and deteriorating.
The fuel pump is essential to delivering the correct amount of fuel to your motor, ESPECIALLY during boost. To make sure your car is not running lean do to not enough fuel being pumped out by your pump, I highly suggest re-wiring your pump.

Step by Step instructions:

FIRST you will need to gather all your supplies. This includes:
Image
Image
Image
Bosch 40 amp relay with 4 prongs
Heat shrink or butt connectors (I HIGHLY recommend heat shrinkers)
12 gauge wire, yes I said 12 gauge
Soldering iron
Electrical solder material
Butt connectors
20 AMP inline fuse

Remove negative terminal from battery before you begin!

Step One:
Empty your trunk and pull the carpet and board out to expose your fuel pump cover. There is no need to pull the fuel pump out.
Image

Step two:
Unscrew the cover to the fuel pump wire harness. There are two covers, unscrew the one on the right next to the strut.

Step three:
Unclip the blue plug

Step four:
Locate the power wire. It is the white/purple wire.
Image
Cut that wire in half. Now you have one portion of that wire going towards the fuel pump, and the other portion going towards the blue clip.
Solder the 12 gauge wire to the positive wire that is connected to the fuel pump and then connect the other side of that 12 gauge wire to pin 87 on your relay. Solder the other portion of the positive wire that connects to the blue clip to a 12 gauge wire, and then connect the other side to pin 86.

Step five:
Connect a 12 gauge wire to your battery and run a 20 amp in-line fuse on that wire, then run the other side of that to pin 30 on your relay.
Image
Image

Step six:
Connect a 12 gauge wire from your negative battery cable and connect the other side of that 12 gauge wire to pin 85.

DONE!
This is what it looked like when finished. I screwed my relay into the fuel pump cover to hold it tightly in place.
Image

Notes:
I made my own in line fuse by getting two butt connectors and connecting them to a 20AMP fuse. This is ghetto, but its what I had and works:
Image
Image

I connected butt connectors on my relay prongs to make it easy to connect the wires:
Image

Here is a diagram so you can visualize it better:
Image

MAKE SURE TO PLUG THE BLUE CONNECTOR BACK IN WHEN YOU FINISH

I recommend you test voltage at the fuel pump before and after this mod if you want to see the difference.
Last edited by shift_down on Thu Jul 04, 2013 9:01 pm, edited 2 times in total.
Come at me bro

Fast
Reliable
Cheap;
You can only pick two, so choose wisely!

My build thread: http://www.ka-t.org/forums/viewtopic.php?t=57539
User avatar
shift_down
SuperMod
 
Posts: 1833
Joined: Mon Nov 28, 2011 11:00 am
Location: tulsa oklahoma

Re: How to rewire your fuel pump for max efficiency!

Postby Rick » Thu Jul 04, 2013 7:33 pm

Sticky! Good write up!
••••••••••••••••••••••••
No... I don't own a 240 anymore!
••••••••••••••••••••••••
"Don't remind me of my failures, I haven't yet forgotten them"
User avatar
Rick
KA-T.org Co-Owner
KA-T.org Co-Owner
 
Posts: 1135
Joined: Sun Feb 01, 2004 7:14 pm
Location: San Diego, CA

Re: How to rewire your fuel pump for max efficiency!

Postby Marcus » Mon Jul 08, 2013 5:18 pm

I'd be timid with the spade terminals unprotected so close together. To help I will bring my electrical pigtail book back with me tomorrow so we can have a part number to use or x-reference to make this even better. Great write up!
User avatar
Marcus
Wearer of Missing G-Strings!
 
Posts: 3328
Joined: Tue Sep 28, 2004 5:33 pm

Re: How to rewire your fuel pump for max efficiency!

Postby airman » Tue Jul 09, 2013 5:27 am

Nice write up shift.

Marcus wrote:I'd be timid with the spade terminals unprotected so close together. To help I will bring my electrical pigtail book back with me tomorrow so we can have a part number to use or x-reference to make this even better. Great write up!


When I did mine, I soldered the wires to the relay and ran heat shrink over them. You could also get the plastic insulated ones, or a relay socket 'pigtail' if you will that has the bare wires coming off of it.
R.I.P. 1990 Red Hatch - DOHC 5 speed // CP 9:1 - Eagle Rods - Clevite - ARP // Holset HX35 - 20psi daily - MSPNP2
8-bit wrote:You could spend your life building a ladder to the moon, or work for 5 years to pay for a trip.

Thinking about E-Mance? Think twice and read this:
viewtopic.php?t=45057&postdays=0&postorder=asc&start=0
User avatar
airman
KA-T.org OWNER
 
Posts: 2132
Joined: Tue Jun 16, 2009 12:51 pm
Location: Anderson, SC

Re: How to rewire your fuel pump for max efficiency!

Postby shift_down » Tue Jul 09, 2013 9:12 am

I heat shrunk them after putting the butt connectors on, I didn't trust them just hanging out like that either.
Come at me bro

Fast
Reliable
Cheap;
You can only pick two, so choose wisely!

My build thread: http://www.ka-t.org/forums/viewtopic.php?t=57539
User avatar
shift_down
SuperMod
 
Posts: 1833
Joined: Mon Nov 28, 2011 11:00 am
Location: tulsa oklahoma

Re: How to rewire your fuel pump for max efficiency!

Postby Marcus » Tue Jul 09, 2013 10:13 am

Ahh I see. Well carquest has a 4 wire pigtail number S-706 and a 5 wire pigtail number S-654. I assume the 4 wire excludes the center terminal. Edit: I hope other stores can cross reference the numbers...however this might help.

Image
Image

Also if someone would want to get perfectionist style on the fuse as well....I have this information to offer.

Image
Last edited by Marcus on Wed Jul 10, 2013 4:36 pm, edited 2 times in total.
User avatar
Marcus
Wearer of Missing G-Strings!
 
Posts: 3328
Joined: Tue Sep 28, 2004 5:33 pm

Re: How to rewire your fuel pump for max efficiency!

Postby shift_down » Tue Jul 09, 2013 10:22 am

I've never heard of those before, I'm going to check them out.
Come at me bro

Fast
Reliable
Cheap;
You can only pick two, so choose wisely!

My build thread: http://www.ka-t.org/forums/viewtopic.php?t=57539
User avatar
shift_down
SuperMod
 
Posts: 1833
Joined: Mon Nov 28, 2011 11:00 am
Location: tulsa oklahoma

Re: How to rewire your fuel pump for max efficiency!

Postby airman » Thu Jul 11, 2013 3:52 am

You can probably find them at a local auto parts store. But I'm sure they're $10+
R.I.P. 1990 Red Hatch - DOHC 5 speed // CP 9:1 - Eagle Rods - Clevite - ARP // Holset HX35 - 20psi daily - MSPNP2
8-bit wrote:You could spend your life building a ladder to the moon, or work for 5 years to pay for a trip.

Thinking about E-Mance? Think twice and read this:
viewtopic.php?t=45057&postdays=0&postorder=asc&start=0
User avatar
airman
KA-T.org OWNER
 
Posts: 2132
Joined: Tue Jun 16, 2009 12:51 pm
Location: Anderson, SC

Re: How to rewire your fuel pump for max efficiency!

Postby toky042 » Fri Jul 12, 2013 11:57 am

nice write up :)
toky042
Driving Mom's Station Wagon
 
Posts: 25
Joined: Wed Dec 05, 2007 11:59 pm

Re: How to rewire your fuel pump for max efficiency!

Postby chillmieste » Thu Jul 18, 2013 5:18 pm

sweet write up may have to do this to mine. i go through walbros like every 8 months
chillmieste
Dreams of owning a 240!
 
Posts: 53
Joined: Thu Feb 04, 2010 8:46 pm
Location: tamarac, fl

Re: How to rewire your fuel pump for max efficiency!

Postby Niys » Fri Jul 19, 2013 11:17 am

I this for just the stock pump or is this something to do for you aftermarket ones as well.
Niys
Driving Mom's Station Wagon
 
Posts: 26
Joined: Fri Aug 24, 2007 4:55 pm
Location: Woodbridge, Virginia

Re: How to rewire your fuel pump for max efficiency!

Postby shift_down » Fri Jul 19, 2013 2:07 pm

It affects the wiring, so anything at the end of the positive wire gets affected.
Come at me bro

Fast
Reliable
Cheap;
You can only pick two, so choose wisely!

My build thread: http://www.ka-t.org/forums/viewtopic.php?t=57539
User avatar
shift_down
SuperMod
 
Posts: 1833
Joined: Mon Nov 28, 2011 11:00 am
Location: tulsa oklahoma

Re: How to rewire your fuel pump for max efficiency!

Postby airman » Sat Jul 20, 2013 7:41 am

Niys wrote:I this for just the stock pump or is this something to do for you aftermarket ones as well.


You definitely want to do this with aftermarket fuel pumps, but it couldn't hurt for stock ones. If you're running boost, you should at least have a Walbro 255 or something.
R.I.P. 1990 Red Hatch - DOHC 5 speed // CP 9:1 - Eagle Rods - Clevite - ARP // Holset HX35 - 20psi daily - MSPNP2
8-bit wrote:You could spend your life building a ladder to the moon, or work for 5 years to pay for a trip.

Thinking about E-Mance? Think twice and read this:
viewtopic.php?t=45057&postdays=0&postorder=asc&start=0
User avatar
airman
KA-T.org OWNER
 
Posts: 2132
Joined: Tue Jun 16, 2009 12:51 pm
Location: Anderson, SC

Re: How to rewire your fuel pump for max efficiency!

Postby BrokeKAT561 » Sun Jul 21, 2013 4:27 pm

Damn I did that and it worked out so much haah, before I was putting straight power from the battery, and have a switch so if I forgot to turn it off my battery would die haha!
BrokeKAT561
Driving Mom's Station Wagon
 
Posts: 30
Joined: Wed Jul 10, 2013 9:47 am

Re: How to rewire your fuel pump for max efficiency!

Postby slo240 » Sat Jul 27, 2013 8:42 am

Right now my car is leaning out at wot, would this rewire fix that?
JIC FLTA2s, tanabe underbody brace, JIC RUCAs, JIC traction rods, JIC rear strut bar

Built ka24de: Eagle rods, JE pistons 9:1, APR main & head studs, beck & arnley bearings, felpro gasket kit, N62 MAF, dual exhaust cam setup, AFC Neo, Innovate MXT-L wideband
slo240
Driving Mom's Station Wagon
 
Posts: 43
Joined: Tue May 27, 2008 3:20 pm
Location: Aurora, CO

Re: How to rewire your fuel pump for max efficiency!

Postby jmac636 » Fri Sep 06, 2013 8:39 am

If your leaning out going WOT then its either the wiring to the fuel pump or the fuel pump itself going bad. Its common for the wiring to have a bad connection and dropping voltage. I like to redo the ground wire also. Great write-up btw.
1995 S14 daily built block nismotronics sr20det Ecu running my ka-t, synergy green S14 5.3l turbo 240sx 1/4 mile traps 135mph on 13psi and dr's.
Holset HE341 Install thread woohoo!!
forums/viewtopic.php?t=48692
http://www.playloudclothing.com/
User avatar
jmac636
Knows Some Stuff About 240's!
 
Posts: 414
Joined: Wed Aug 13, 2008 11:10 am
Location: TEXAS

Re: How to rewire your fuel pump for max efficiency!

Postby mig_100 » Thu Sep 19, 2013 3:40 pm

Great write up. You can also wire in a kill switch in this location
mig_100
Learners Permit
 
Posts: 10
Joined: Mon Oct 08, 2007 1:07 pm
Location: Baltimore, MD

Re: How to rewire your fuel pump for max efficiency!

Postby street_240sx » Wed Oct 02, 2013 3:22 pm

So what's the point of this? Is it just to have new wires for you fuel pump?
03 evo8 gsr: stroker 2.3 ;)

04 evo8 gsr: totalled

96 integra gsr: sold

89 s13 coupe: stock dohc, gt3076, megasquirt

started 3/15/08, running 1/18/09, finally turbo 2/9/14 lmfao
User avatar
street_240sx
Belongs To The TOP CONTRIBUTING MEMBERS!
 
Posts: 1919
Joined: Sun Feb 10, 2008 7:31 pm
Location: 520 AZ

Re: How to rewire your fuel pump for max efficiency!

Postby shftqikr » Mon Feb 02, 2015 8:29 pm

Jut noticed this write up. Great way to avoid voltage drop on the fuel pump. This is a classic DSM move on 1g's. How much of a voltage drop was recorded before and after this mod?
shftqikr
Learners Permit
 
Posts: 9
Joined: Mon Feb 02, 2015 8:25 pm
Location: Middletown, OH


Return to KA-T Tech. Basic

Who is online

Users browsing this forum: No registered users and 104 guests

cron