Is there a write-up anywhere for this? I can't find it on the Sogi site... Thanks!

what's it do

Provides 12 volts to the fuel pump at all times instead of 9 ( I think ) at lower RPMS.

I need some info on this too!!!! Does anyone know if a walbro requires the re-wire? Cuz I'm hitting off the charts lean at the first blip of the throttle.... maybe?

ok better question... whats the point to have 3 extra volts to your fuel pump?

Current x Voltage = Power


1 Amp x 9 Volts = 9 Watts

1 Amp x 12 Volts = 12 Watts.


Make sense?


More power = more flow. I would guess... :D

Current x Voltage = Power


1 Amp x 9 Volts = 9 Watts

1 Amp x 12 Volts = 12 Watts.


Make sense?


More power = more flow. I would guess... :D


i understand the electrical part of it, just don't get what it's going to do to the fuel pump, like let it pump more fuel or something.

Yes, it makes the pump work harder, to supply more fuel. No one knows how it is done?

I had my walbro installed when I had my engine rebuilt, wonder if they did the 12v rewire, what will happen if you don't do the 12v rewire?

You get inconsistent flow as power is alternated between WOT and cruise. By bypassing the resistor you get 12volt constant instead of switched between 12 and 9.

It's a very simple mod, just look to see if the resistor has been bypassed or not.

You get inconsistent flow as power is alternated between WOT and cruise. By bypassing the resistor you get 12volt constant instead of switched between 12 and 9.

It's a very simple mod, just look to see if the resistor has been bypassed or not.


So... the resistor... that's under the hood on the driver's side right?

It is on the passenger side.

no no no to get the fuel pump to get full 12 volts is to by pass the resitor in on the fuel pump cradle then you will have 12 volts not the restor in the passger side of the einge bay


funny thign thou most 86 and 87 have 12 volt pumps well the other's got toned down

oh yae puttign more power to your 15+ year old pump is not good of an idea some time it work for year's some times they die fast

no no no to get the fuel pump to get full 12 volts is to by pass the resitor in on the fuel pump cradle then you will have 12 volts not the restor in the passger side of the einge bay

no, you bypass the resistor on the passenger side of the car. what fuel pump cradle are you talking about?

right here is what you're bypassing, simply by connecting those two wires after cutting them, or placing a jumper wire in the body side of the connector...

http://www.cygnusx1.net/supra/library/TSRM/fi/FI_115.html

-shaeff

there is all so restor on the cradle it self some have them some don't

mine read 11.5 whe test mine wiht and with out it

in the end i whoudl nto run at 12 volts any way to hard on a old pump

there is all so restor on the cradle it self some have them some don't

mine read 11.5 whe test mine wiht and with out it

in the end i whoudl nto run at 12 volts any way to hard on a old pump

This is not for people running old stock pumps this is for the walbro 255 users. I did this mod and now i go romp on the pedal, instant throttle let my foot off and it falls back to a nice easy idle. Before I did this mod if I were to do that the car would fall bog to idle bog out and die.

DOing the 12v pump mod aint gonna get you shit for power gain

it might make u run pig rich and waste more gas

to increase power u gotta increase boost, more flow of air and fuel not just fuel

intake , downpipe, bigger exhuast, bigger injectors

I dont think they are tryin to gain power but smooth out the transition from WOT to idle. and most people who would do this mod probably already have BPU and then some. I dont know anything about this mod but what i gathered is a more consistent fuel flow all across the board.

good to see you on this forum Shaeff (my name on I-supra is T-funk)

listen to Shaeff he knows quite abit

DOing the 12v pump mod aint gonna get you shit for power gain

it might make u run pig rich and waste more gas

to increase power u gotta increase boost, more flow of air and fuel not just fuel

intake , downpipe, bigger exhuast, bigger injectors

see, its funny, you say that like its a fact, but you simply could not be anymore incorrect.

thinking " How does he know " ?

well, I did the 12V mod, and I gained much more LOW >1500 RPMS power. :)

I dont think they are tryin to gain power but smooth out the transition from WOT to idle. and most people who would do this mod probably already have BPU and then some. I dont know anything about this mod but what i gathered is a more consistent fuel flow all across the board.

good to see you on this forum Shaeff (my name on I-supra is T-funk)

listen to Shaeff he knows quite abit

you've got it, sir. :) glad to see you here as well. you should check out SM. it's a good one!

-shaeff

DOing the 12v pump mod aint gonna get you shit for power gain

it might make u run pig rich and waste more gas

to increase power u gotta increase boost, more flow of air and fuel not just fuel

intake , downpipe, bigger exhuast, bigger injectors

Actually, in any internal combustion engine, torque is proportional to the amount of fuel you can burn. Boost just alows more fuel to be consumed in combustion.

It is true that just increasing fuel flow over stock with no other changes doesnt do much.

This is not for people running old stock pumps this is for the walbro 255 users. .

Not true.... I ran this for 8 years on my car. Was able to push out over 440rwhp on my supra on stock fuel pump with this mod. It works. More fuel with more airflow = more HP. I agree that on a stock Supra you will see limited to no results buy doing this. If you ahve upgraded injectors or turbo this is a MUST of you dont have a walbro already. I have had my supra for over 8 years now. I finally just bought a Walbro..... didnt need it. 12v mod works great but the only downfall is you will eventualy wear out the pump. For me my pump lasted over 8 years. Just depends.... and I ran it pretty hard alot of the time.

Over those 8 yrs was it daily driven or the sunday garage queen?

BTW, I've never been to/heard of i-supra... thanks for letting me know about one more lesser known forum :thumbup:

Oh no! Not this again!

No one bypass the resistor. It's a very stupid "solution."

I have talked this to death on Supraforums...in TWO threads. Here are the links:

12V mod 1 (http://supraforums.com/forum/showthread.php?t=317271)
12V mod 2 (http://supraforums.com/forum/showthread.php?t=317247)

Very bottom line: it drives electrical engineers insane if you jump the resistor, because the resulting circuit is a complete joke. Instead, cut the yellow wire in the FP relay harness. After this, you can either leave the resistor as-is or rip it out with nothing in its place, and you will have a sucessful 12V mod.

Jumping the resistor still causes a nasty transient voltage to the pump when the ECU thinks it is switching to or from 9V supply.

Wow, I've seen one of those threads before (ironically the one which links to the other, or do they both do that? haha) and I didn't actually even pick up on your excelent posts there appleguy.

Thanks tho, I learned something new!

youre best off doing a REAL 12v mod... like i do on every car that needs a fuel system.

eliminate the stock relay and resistor pack.

run a dedicated 10ga power wire from the output side of the 100a alternator fuse into the trunk.

install a bosch 30a relay.

10ga power input to the relay, 14ga power out of the relay to the stock fuel pump harness.
12ga ground wire from relay to chassis
use the stock fuel pump wire, BR, to switch the relay on and off.

you can use the ecu FP+ signal from the COR and send it back through the 12v+ FP power wire and run that to the wire. it will be the same signal to turn the pump on, just travellng down a different wire and triggering a different relay. just trace the power supply through this diagram. youll see which wires need to be connected to create a sufficient path of power to your new relay.

http://cygnusx1.net/supra/library/Wiring/pages/Page_046.gif

Power comes from EFI main relay, to the COR relay via wire B-R. power comes out of the COR via wire L-B. the power goes from the COR to the FP relay via the L-B wire. power comes out of the FP relay via B-R wire and goes to the fuel pump directly. so your NEW bosch relay will be switched on when the EFI main relay is switched on. you can either leave the stock relay and resistor there and cut the Yellow wire as Apple guy said, or remove EVERYTHING and tuck the harness out of the way for a clean uncluttered engine bay. its up to you.

if you get REAL creative, you can rewire the fuel pump harness inside the tank on the hanger, and also coming from the hanger to the chassis wiring. i personally would do this but its not necessary to get full voltage to your pump/s.

hope that helps.

Over those 8 yrs was it daily driven or the sunday garage queen?

BTW, I've never been to/heard of i-supra... thanks for letting me know about one more lesser known forum :thumbup:

I would say during those 8 years it was driven 3-5 times a week.

All the resisitor does it cut back current and voltage. How would that leave the circuit a joke?

Trey

Good drawings BTW