Fuel pump hardwiring

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Structure240sx
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klattr1 just brought this to my attention the other day. i bought the few things need but wasnt completly sure exactly which wire goes where

i have 12g wire30a inline fuse30amp relay

the relay has 4 terminals

terminal from power sourceterminal for groundterminal from switchterminal for lights/horns (this case for the fuel pump?)

anyone know what the "triggerside" would be? or is that maybe jsut for bosch relays? theone i got was the onyl onei could find at the local parts store, some no name brand


DRIFTEADOR
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trigger is your stock signal wire. I suppose the white/purpleish one.

Structure240sx
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couldnt be because each side of that wire is used for something else it seems, not sure

:: orion ::
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Are the pins #'d...???

If so, like a typical Bosch relay...do this:

85 and 86 are for the trigger/switch...one needs a positive (+) switched wire to turn it on, one needs a ground. So run your stock fuel pump (+) to one, and run a short ground to the other.

Now, run a (+) feed directly off the battery to 30...this is the power supply wire.

87 is run to the fuel pump...use the other end of the stock wire you cut, or run a new one.

See here for a diagram, maybe it will help:

http://www.6066gmctrucks.org/BoschRelay.htm

...but the idea is that you're now using the stock wiring to turn on the relay, which will then conect 30 and 87, giving the fuel pump a full 12 volts of big amps.

- Brian

DRIFTEADOR
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Quote »

terminal from power source - direct 12v powerterminal for ground - direct groundterminal from switch - body harness/main relay side of stock pump power wireterminal for lights/horns (this case for the fuel pump?) - fuel pump side of stock power wire

[/quote]thats 4

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virus77
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Good post, Ill be all over this during the weekend.

Structure240sx
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they are number exactly how you said brian. i got to go grab my fsm and find the power wire for the s14, different than s13 i jstu found out after changind my fuel sock

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virus77
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post the wire when you find it, make my job easier.

:: orion ::
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If it's not posted once I get home later, I'll take a pic of mine...so you can see how I did it and what the wire color is for an S14.

- Brian

Structure240sx
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does black/yellow ring a bell? jsut a quick look at my fsm and thats what i found

:: orion ::
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Sounds right...

To test, unplug the harness, stick a test light on it, and see what happens when you turn the key to on...it should light up for ~3 seconds, then go off.

- Brian

Structure240sx
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its about damn time for me to go get a test light/voltage tester.

im literally in the middle of this. im positive its the black/yellow. the FSM has a black/yellow goint o the fuel pump and a black coming out. the 2 pin plug for the the power and ground wires for the fuel pump are black/yellow and black. give me about 10 more minutes and we'll find out.

on a side note, im very surprised this hasnt been discussed that much. i know it seems more of a high HP thing (300+) but there have been alot of guys with lots of power for a while now.

:: orion ::
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Yes, it's the B/Y wire...

See the pic of mine, here:



Looking at that, the bottom pin is (30), the feed (I ran dual ~16 gauge straight off the battery).

Top pin is (87), which is the stock black/yellow wire (+) going directly to the fuel pump.

Pin on the left is (85), the trigger wire (stock B/Y).

Pin on the right (86) is the ground, you can see I wrapped it around an just grounded it to the realy mount.

Hope that helps...

- Brian

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klattr1
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Brian, thanks so much for the picture and write up. This will help so many people with the wiring part. I emailed you about something.

Structure240sx
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yea yours looks great, better than mine

skatanic28
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what pumps are you guys running that you need to do this? or are you just trying to get more voltage to the pump?

edit: nevermind, i read the FA threads. i was not aware that there could be problems with the stock wiring, thanks!

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klattr1
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Orion,im just curious if you have the labelings of what 85 and 86 are wrong? cuz I have read several DSM forums about the Walbro rewire and they tend to use 85 for the ground and 86 for the stock trigger wire.

here's where i pulled some of the info from:

http://www.plymouthlaser.com/fwdwire.ht ... relay.html
Modified by klattr1 at 4:06 PM 4/18/2005

:: orion ::
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I cooul have it backwards...but I'm under the impression that the polarity of the trigger and ground pins are inconsequential.

i.e....from the "vfaq" one, he quoted:

"Note that a very quick and easy anti-theft additive is to add a switch to the 85 wire (or 86 if that is what you use for ground)..."

...that also makes me believe it doesn't matter which is which...it just activates the relay when it's juiced, from either end.

- Brian

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klattr1
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i see. obviously it works on your car. haha. thanks alot for the update.
Modified by klattr1 at 5:06 PM 4/18/2005

DRIFTEADOR
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did you guys that have done this happen to test the pump's voltage before and after?

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klattr1
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Orion,

here's a tech post I made on KA-T.org Tech section.

Is it error free? If anyone else sees anything else to be added or mistakes, let me know. This modification will be handy for those KA-Ters pushing the limits of their setups.

http://www.ka-t.org/tech/

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klattr1
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DRIFTEADOR wrote:did you guys that have done this happen to test the pump's voltage before and after?
i know someone that got only 10v at the pump but this is at high rpms on a 438 rwhp KA setup.

:: orion ::
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klattr1 wrote:Is it error free?
Looks good by me...

Well done, and thanks for posting it for all to use.

- Brian

NateDogg
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Would this be beneficial in keeping the fuel pressure up in between shifts in a N/A KA24DE? With 12.5V at the pump at idle?

nissanfanatic
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Seems like a good upgrade for anyone running an upgraded fuel pump.


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