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Re-wiring Your Fuel Pump


R 2 THE J

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To all SAU's,

There is anotherthread on the forum that describes how to re-wire your fuel pump so it recieves the full 13.8v that comes direct from your battery.

PARTS USED-

-1 metre of 6mm Red Power Cable

-2 metres of 6mm Black Negative Cable

-5 x 30 AMP Fuses

-1 x Fuseholder to suit Fuses

-1 x 12v DC Relay or Horn Relay (You'd want a relay with big terminals to fit your 8GA Cables)

-2 x Large Eye Connectors to suit your 6mm Cables (Big enough to fit on your Battery and Chassis Bolt)

-Pack of 25 Fork Connectors to connect to your Relay Terminals

-Pack of 10 Straight through connectors to suit 8GA cables

TOOLS-

-Pliers

-Crimping Tool

-Phillips and Flat Head Screwdrivers

-10mm Socket and Ratchet

-Multimeter (To check your voltage after modification)

LEVEL-

Low to Medium

I've tried to explain it a lot more in depth to make it easier

DURATION-

1hour - 1hour 30mins (depending on electronics background)

CAR IN USE-

1994 R33 gts-t

DIRECTIONS-

1. Disconnect the negative from your battery, loosen with 10mm socket and remove. This is to make things safer and so you don't damage your ECU.

2. Locate your fuel cell, mine was in the boot on the right hand side of my battery.

You will see cables taped up leading towards into the fuel cell lid. Start unwrapping the tape approximately 100mm from the the fuel cell lid until approximately 150mm of cable is visible. This allows enough cable to be cut and joined.

3. You will find 5 wires in total. You may notice that 2 of these cables are a little larger in diameter than the rest. These are your POWER wires feeding your pump. The other 3 smaller diameter wires are for your fuel level sensor.

YOUR ACTIVE CABLE IS THE BLUE ONE.

YOUR NEGATIVE CABLE IS THE WHITE ONE.

4. Cut both of these wires in the middle of the section you unwrapped.

5. With the white cable that you cut, strip the cables back 10mm and twist them together and crimp one side of your straight through connectors onto these twisted cables. Join your 6mm Black Cable to the other side of the straight through connector and run it neatly to your point of earth on your chassis using an eye connector (loosen nut/bolt with 10mm socket, place eye connector on and tighten back up). Now your fuel pump is totally grounded.

6. You now have your two blue POSITIVE wires that you cut leftover. Connect the side of the blue wire that comes from your computer to the coil of your relay (Terminal A1) using your fork connectors. This will be your switch wire, so when your computer tells the fuel pump to turn on it will switch the relay on. Then connect the other side of the blue wire that leads to the fuel pump to your N/O (Normally Open) side of the relay with another fork connector.

Normally Open means that the switch will be open in it's normal state (when there is no power going to the coil), when power is put on the coil (when the fuel pump switch turns on) it will close the switch and thus turn on your fuel pump.

8. Now Connect your 6mm Red Cable to the positive of your Battery with your Large Eye Connector and neatly run it to your relay. Connect this to the other side of your normally open switch with a fork connector. This will now feed your fuel pump with full 13.8v.

9. Your last connection will involve you to connect your 6mm Black Cable to the other side of the coil (A2) on your relay using a fork connector, and neatly run this wire and join it to your point of earth on your on your chassis (loosen with 10mm socket place eye connector on and tighten back up).

10. Here is a detailed wiring diagram. Obviously you can't see white wires on a white background so instead i've made this YELLOW.

7591FUEL.jpg

11. Double check all your wiring. Reconnect your negative terminal on your battery and start your car.

Check the voltage going to the pump, you should now have 13.8v.

Hope this has helped out a lot of people.

Any questions, feel free to ask.

RJ

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I have just done this to my r32 with a rb25det. I just ran a new wire from the battery straight to a circuit breaker then more wire to the old power wire on the fuel pump plug. Added a relay in there so it comes on with the ignition. Does this sound right. Seems to get 12.8 volts at all times now but not sure if it is a safe way to do it.

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I have just done this to my r32 with a rb25det. I just ran a new wire from the battery straight to a circuit breaker then more wire to the old power wire on the fuel pump plug. Added a relay in there so it comes on with the ignition. Does this sound right. Seems to get 12.8 volts at all times now but not sure if it is a safe way to do it.

Yeh its fine mate, aslong as you're still using your existing fuel switch wire to switch your coil on the relay you should be sweet.

The power from the battery should ONLY be powering your fuel pump.

This is so if you are in a crash or anything the fuel safety cut out will still switch off your fuel pump through your existing switch.

Hope that made sense.

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  • 1 year later...

Will this have any effect on the battery. Mine was just rewired and I notice the batt voltage dropped to 9V after like 2 days of not driving her. It has gone to the point of having difficulty to crank her up.

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Will this have any effect on the battery. Mine was just rewired and I notice the batt voltage dropped to 9V after like 2 days of not driving her. It has gone to the point of having difficulty to crank her up.

it won't affect the car when the ignition is off

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I was told that in the event the car had a crash, the fuel will be sprayed all over coz the ecu can't cut off power to the fuel pump. Are there any truth to this or it is perfectly safe to wire it this way?

Any idea??

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the wire that has come from the ecu to fuel pump is now the trigger wire for the relay when you do this, which means if you did have an accident and the ecu wants to turn off the fuel pump it still can cause i will just trigger off the relay which will stop the connectivity from the battery to the fuel pump. so pump will be off.

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i did this recently, i had a bosch 040 in tank still running off the standard loom and i checked the voltage going to the pump and it was only 10.5v after runnin power from the battery to the pump just the noise increase told me it was working 1 hell of a lot better fuel presure shot up by about 10 psi at the regulator

i recomend this to anyone with a aftermarket fuel pump

sorry R 2 THE J but i think your wiring diagram is confusing....

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  • 10 months later...

R34 gtt fuel pump wiring

Green white needs to go from fuel pump to chassis earth. 

Green white from ecu to pin 86

Black yellow from ecu loom to pin 85

Black yellow from fuel pump wiring to pin 87

battery 12volt supply to pin 30 with a 30amp fuse at the battery end of this wire

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If I want to do this, does this mean I need to open my fuel tank again coz I'm wondering if its safe to increase the wires outside the tank and not the inside(increased amperage and voltage flow will heat up the smaller wire inside).

Are you guys changing the wires inside the fuel tank(from inside the cap to the fuel pump it self)? If so what wires are you using because I really wouldn't trust regular wires near petrol as the plastic/shielding shit is bound to wear off and crack like arse and I really don't want sparks inside the fuel tank. In my old skyline I noticed they added two wires in place for each terminal going to the lid of the pump but inside was the same(I think).

What I done was remove the whole fuel tank lid and pump setup out of my old car and dropped into the new one and just plugged in the standard loom.

Edited by SargeRX8
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we just connected into the wires outside the tank lid - easy way, dont think its an issue, besides when u open the lid, u need to change the goddam black rubber seal as it expands and is hard to put back in and starts leaking - I have a fuel smell in my boot now..where do i get the new seal from?

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we just connected into the wires outside the tank lid - easy way, dont think its an issue, besides when u open the lid, u need to change the goddam black rubber seal as it expands and is hard to put back in and starts leaking - I have a fuel smell in my boot now..where do i get the new seal from?

i got it from Nissan for 14 but there is a 3 week wait on it. You can get em fro kudos for 30. Nissan get them from japan they don't hold stock locally.

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