Fuel Pump Direct Feed Rewire.

[ali-turko]

pidibump!!

I read the whole 12 page thread. Most people talk about r33 or 32 gts or 32 with Aftermarket pump.

What about Stock fuel pump on a GTR 32 with something like 350whp.

Any benefit?

dude the fuel pump is coming on near 20 years old id replace to be safe

i would'nt trust the stock fuel at 13.8volt could cost you are motor

[nato_wp]

one thing that does confuse me about this tutorial is that (taking it from the first post) the use of a 60A relay and a 30 amp fuse but then its all spliced into the last little bit of stock loom, which is much lower current rating than 30A as well as the wires actually feeding the pump in the tank, so that is then acting as the fuse, and your 30A fuses are essentially useless because the wires will burn out well before the fuse does

I agree with you.

There is no point having anything higher than a 20amp fuse in your new circuit unless you've replaced the wires all the way to the pump terminal.

Most people are getting current draw of around 10amps at the pump, so I don't see any reason to have a substantially higher rated fuse?

[gumflapper]

yeh the 30A fuse i drew actually came with the relay... 15A is sufficient... ideally the fuel pump should state the FLC of the unit but when i unpacked it, i dont remember it having any such rating

[TUF250]

question, in the r33 gts-t. is it the green wire your checking from the fuel pump?

If it is I checked mine and I had 11.9 off and 14.05 running which should be fine from the sound of it?

[TUF250]

checked mine again today and the same, std wiring and getting 14v at idle. This is checking the light green coloured wire that goes into the fuel tank. is this the main supply for the pump?

[lowered_skyline]

I recently did this to my 32 , starts and runs perfect but when i turn the ignition completely off the car continues to run on (majority of the time), i noticed the ignition stays on , and the pump itself is still running ,

anyone had this happen to them ?

any help would be awesome !

Franco

[Rb20_180]

lol yeah FrankO,

i had the same thing happen and then i went looking and found this thread. when i 1st did mine i just used some shitty relay i had in a random box, so i replaced it with a new item. was ok for a few starts, then when i put my GTR pump in it kept running again. read in this thread somewhere in the early pages about the relay sticking on if it was on its side. so this arvo i moved my relay into a verticle position and also grounded the pump earth to the body at the same point as the relay earth. Problem solved.

[rondofj]

man all this is confusing as...dosent anybody have actual pictures of grounding which wire where etc..all those grounding the pump wiring to chasis and running wires to the pump positive, need pictures to see where and how the wires run - ie thru the rubber booth at the top of pump etc..

[DVS JEZ]

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

[Spurdo]

so im no expert on electronics, but the likes of the bosch 044 and the walbro etc only draw an absolute max ~18amps according to various charts i've found on the internets. i've got a walbro pump sitting in my shed and the wiring that comes with it's factory plug (on the walbro) is only about 14-16awg which is the same size as the factory feeds to the pump in the nissan cradle. so that suggests to me that those wires are perfectly capable of running the bigger pumps if they are used by the manufacturer of a pump that will need to be capable of running 18amps and theres no need to go running extra large cables on the inside of the tank to feed the pump, and since no one thus far has managed to run the larger cables the entire way to the pump (internal), that would make it a pointless exercise to put thicker wiring inside the tank because the wiring is only as strong as the weakest link (being the factory wiring) which everyone has left there at some point.

i plan to get this done in the next couple of days, but the way i see it a 20A fuse is plenty and 25A wiring to go with it. i dont see how the 8awg cable (rated about 56A) that a bunch of the earlier posters in this thread used was of any benefit over the 25A 10awg(ish) cable that would have been possibly easier to work with (and cheaper).

does this make any sense to anyone or am i way off?

Edited May 9, 2011 by jonboy

[Spurdo]

so i've just done this mod and im now getting 14.0v at the pump and going well. didn't take the cradle out of the tank, and no you do not need to go for 8GA cable as in the original post, that is way overkill. i just used this for positve feed and the same in black for the negative straight to chassis, its rated at 25A which will comfortably accomodate the bosch's and walbro's which are all <20A at maximum draw. im using a 20A 3AG fuse.

im guessing the huge 8GA cables would only really be necessary if you're running multiple pumps?

[gumflapper]

so im no expert on electronics, but the likes of the bosch 044 and the walbro etc only draw an absolute max ~18amps according to various charts i've found on the internets. i've got a walbro pump sitting in my shed and the wiring that comes with it's factory plug (on the walbro) is only about 14-16awg which is the same size as the factory feeds to the pump in the nissan cradle. so that suggests to me that those wires are perfectly capable of running the bigger pumps if they are used by the manufacturer of a pump that will need to be capable of running 18amps and theres no need to go running extra large cables on the inside of the tank to feed the pump, and since no one thus far has managed to run the larger cables the entire way to the pump (internal), that would make it a pointless exercise to put thicker wiring inside the tank because the wiring is only as strong as the weakest link (being the factory wiring) which everyone has left there at some point.

i plan to get this done in the next couple of days, but the way i see it a 20A fuse is plenty and 25A wiring to go with it. i dont see how the 8awg cable (rated about 56A) that a bunch of the earlier posters in this thread used was of any benefit over the 25A 10awg(ish) cable that would have been possibly easier to work with (and cheaper).

does this make any sense to anyone or am i way off?

yeh ur exactly right saying "wiring is only as strong as the weakest link".

the reason i used 6mm2 cable is because i had the lugs to suit it from work (im an electrician) and in any suituation it is better to oversize the cabling than to undersize it (not to be stupid tho - no need for 16mm2 cable for a 5A circuit lol)

the correct way to calculate what size cable to use for circuits is as follows

Ib <= In <= Iz

where

Ib - Current for which the circuit is designed (Load)

In - Nominal Current of the Protective Device (Fuse/Circuit Breaker)

Iz - Continous Current Carrying Capacity of the Cable (Wire)

so 18A <= 20A <= 25A

means for an 18A circuit use a 20A fuse with cable that can carry 25A of current

AND in Australia we use the metric system not the WERE AMERICANS WHO MAKE UP OUR OWN SET OF UNITS OF MEASUREMENT THAT NO-ONE ELSE ON THE FUC*ING PLANET USES WIRING GAUGE SYSTEM...

generally wiring sizes are as follows

<0.75mm2

0.75mm2

1.0mm2

1.5mm2 - 15A

2.5mm2 - 20A

4.0mm2 - 25A

6.0mm2 - 46A

10.0mm2 - 63A

16.0mm2 - 85A

25.0mm2 - 115A

35.0mm2 - 140A

50.0mm2 - 165A

to inifinity and beyond!

hope some of this information helps you - not my rant on how i hate the AWG system

[DVS JEZ]

what about distance?

ins't it correct to use a higher amp rated cable when going over a certain distance.

[gumflapper]

yeh thats right but for an application like this it is not relivant

its in the millivolts per amp per meter - 0.01 Volts

CSA - AMPS - Voltage Drop (mV/A.m)

1.5mm2 - 15A - 29.4

2.5mm2 - 20A - 17.6

4.0mm2 - 25A - 10.9

6.0mm2 - 46A - 7.29

just remember that these values are approximates and that the cable you buy may be SLIGHTLY different. not enough to make a lot of difference tho. these values i use are for triangle cables which we get from melbourne.

[mico]

does anyone know how to do this on 32 gtr ? which colour wires are what ??

[mico]

k so the wires to cut on 32 gtr are the yellow/black (power) and the white or peachy colour (earth). and its the 2 pin plug not the three. for all the dummies out there like me also, i added a glass tube fuse at the batt, incase it shorts in between there and the relay.

Edited September 11, 2011 by mico

[ARTZ]

just thought this may be of interest...

3mm automotive wire is 1.13mm2 and rated to 10 amp

4mm automotive wire is 1.84mm2 and rated to 15 amp

5mm automotive wire is 2.9mm2 and rated to 25 amp

6mm automotive wire is 4.59mm2 and rated to 50 amp

[ARTZ]

Ok so just did this exactly as per gumflapper description..using 5mm wire and a 15 amp fuse

and wow!!!..fuel pressure went from 3 bar to 6 bar..

[gumflapper]

sounds like your fuel pump is getting all of the electricity it needs to perform as intended

[ARTZ]

yeah and then some. I never expected such a huge increase

The pump started making a weird screech noises that had me worried, but it was ok once I dropped the fuel pressure back to 3 bar...

I had thread the whole thread but I was still lost until I saw your diagram..a good picture tells a thousand words..