Fuel Pump Direct Feed Rewire.

[Cubes]

Reddrifter,

That depends if you measured 12.25v at full load / WOT.

[RedDrifter]

Reddrifter,

That depends if you measured 12.25v at full load / WOT.

Nah that was at Idle only.

[Duncan]

Thanks Cubes, my car had been having a reall bastard of a problem since the rebuild and we couldn't sort it out - tried all the spark problem reasons (plugs, coilpacks, ignitors, earths, ecu etc etc), turned out to be a problem in the fuel pump wiring.

Working fine now with the setup in this thread we have a lovely 14.2 - 13.8v at the pump now

[Cubes]

Good stuff Duncan.

How many pumps are you running?

[Duncan]

Just a standard pump for me....I assume the problem is in the old wiring, computer or relay somewhere.....but the rewire was simpler than workign through it, with the bonus of a higher voltage at the pump as well

[Andi]

Hey guys I have an R34 and currently its got an amp installed with 0 guage wiring. Along that 0 guage I have one of those Stinger 3-Way splitting block thingies (can't remember the actual name), can I just run an 8 guage from that split to the relay/fuel pump without putting a fuse on the new 8-gauge line? Would the fuse on the 0 guage to the amp be sufficient?

And this all done to the wiring loom that comes out of the metal lid that sits on top of where the fuel pump is located right?

Edited April 11, 2007 by Andi

[Omurru]

Doubtful, if your running 0 gauge to your amp it's probably got a fairly hefty fuse on it. Internal fuel pump only needs a 15 and an external one maybe 30. I went to jaycar and bought relays with a blade fuse built in, makes it much more easier and works out cheaper than buying a relay and a fuse holder

I did mine right to just before the plug, ie. took the lid and the plug of and cut it just before the plug, thinking about it it does seem like a bit of a waste to use 8gauge to the internal pump, the wire from the plug to the pump is only gonna be the pissy standard wire neway....still looks good though I suppose

[The Mafia]

well, I just checked my walboro and it was getting 14.2 volts.

Does this mean I need a bigger pump, and don't need to touch the wiring? Car is a 1996 R33 GTS-T.

Running out of fuel up top.

[Cubes]

Sure does...

The R33's tend not to suffer the low volt syndrome like the r32's do.

So what will it be. Tomei/Nismo or will you put up with the groaning Bosch pumps.

[The Mafia]

well, I'll assume instantly that the Nismo and Tomei pumps will take 6 months to get and are about 5 times the price.

Are the Bosch pumps really that noisey?

Even the intank 040's ?

[GTsauRus]

The R32's do have variable speed pump control.

As soon as you touch the accelerator the pump receives the full voltage.

However, the AP Engineering PFC bypasses the variable speed control. The PFC has the pump running at full speed all the time.

I had tested the fuel pump voltage at idle, stationary with rev's and under load on boost. Voltage hardly varied, 11.2v being the peak.

I did the same test on my 32 gtr and got 11.2 peak on the positive BUT its the negative side that is varied above earth to control the pump voltage so to get a true reading you must test across the pump terminals and not from the positive terminal to earth.

with the gtr modulator the minimum negative voltage is 2 volts above earth. So if you put adirect feed the pump positive the highest pump voltage will be 13.8 - 2 so 11.6 volts at the terminals.

[dangerman4]

well, I'll assume instantly that the Nismo and Tomei pumps will take 6 months to get and are about 5 times the price.

Are the Bosch pumps really that noisey?

Even the intank 040's ?

hey fella

Grab a 044 and head down to pirtek.they will supply you with all the fittings and non return valve to mount the 044 intank.

grab a filter sock from a v8 falcon from your local parts supplier and your away..

simple common sense mod but with more flow then the 040 and wisper quiet.

i have pics if your interested.

Darren

[justin911]

does grounding the neg wire on the fuel pump do the same as this mod ?

or is the main idea that your changing to better quality wire ??

btw i got a 040... shes quiet as can be.. you wouldnt know its there. Alltho when ur down to like 1/4 tank you can hear it chugging away sometimes.

[Cubes]

I did the same test on my 32 gtr and got 11.2 peak on the positive BUT its the negative side that is varied above earth to control the pump voltage so to get a true reading you must test across the pump terminals and not from the positive terminal to earth.

with the gtr modulator the minimum negative voltage is 2 volts above earth. So if you put adirect feed the pump positive the highest pump voltage will be 13.8 - 2 so 11.6 volts at the terminals.

I think I follow what you are saying...

I did my testing across the pump terminals. By earthing the multimeter to chassis it picked up 0.5v.

Also.. the GTR and GTST's use a different modulation setup, not sure on the specifics but the GTR ecu has 2 outputs high/low where as the GTST has one.

[Andi]

Can I just use the item here to do this guys? Will save me having to buy a fuse holder and fuse. 30amp should be enough for a single pump right?

http://www.jaycar.com.au/productView.asp?I...=&SUBCATID=

Also, am I suppose to be dong this UNDER the lid, or ontop of the lid? My car is an R34 GTT and when I had a look again today theres a metal lid with a plug there that has about 4-6 wires. How am I suppose to run the 8-guage power and earth through the lid if its solidly sealed?

Thanks,

Andy

[Duncan]

Yeah thats exactly what I used. Easier to mount, find, change, use etc. 30amps is plenty

[Duncan]

I'm not familiar with the 34 GTT lid, on the 32 there is a rubber grommet that 5 wires run though, I just ran the additional wire through the grommet. You could just tap into the standard wiring if you need to but its not ideal

[heller44]

Looking at this diagram, after the fuel pump relay there is something labelled an 'air regulator'.. what is it?

Also the wiring colours that cerbera quoted in the first page are totally diferent to what I seem to have. I went through the hassle of pulling the pump to double check as what I was measuring didn't correlate at all. My pump is White/purple for +, Blue/red -, and yellow and yellow/blue for the gauge set. Anyone have similar?

james.

Here is a wiring diagram for the RB20DET. It clearly shows the fuel pump setup.

[Cubes]

Not really sure; from what I can see its pretty straight forward whats going on.

When the FPCM receives the signal from the ECU the the voltage earths directly.

When the FPCM doesn't receive the signal from the ecu the earth passes through the dropping resistor.

The GTR is essentially identical apart from the FPCM containing the dropping resistor and receiving 2 signals from the ecu to determine if the fuel pump is high or low.

[Captain Drift]

In the R33 on the rear shelf is a fuel pump box that regulates the current for the fuel pump no one seems to mention that? Have people just removed this ?

On a 95, R33 should i need to re-wire the whole pump or just replace the battery earth and possibly fit an engine bay earthing kit?