fuel pump direct battery power - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

jeremy242 · 10-18-2010, 04:39 PM

I have been advised that i should wire my fuel pump dirctly to the battery to reduce voltage drop. Can i just use the existing power source for the pump to trigger the relay and power the pump? Is it really that easy? Obviously i still have to wire up the rest of the relay but is that it? Thanks

R33E8 · 10-18-2010, 05:15 PM

Yes. it's really that easy..

Rabboni · 10-18-2010, 05:21 PM

If voltage drop through a relay was that much of a concern then they wouldnt be used at the factory. Dont wire it directly to battery power,just use the existing setup.

jeremy242 · 10-18-2010, 05:24 PM

I already have the battery in the back as it is, i would be using the factory fuel pump wiring as the trigger for the new relay to directly connect the pump to a good 12v source

jeremy242 · 10-18-2010, 05:29 PM

i was more concerned with the 21 year old wiring that it was having to travel through rather than the factory set up

roboticnissan · 10-18-2010, 05:37 PM

Use the existing relay.

nieko · 10-18-2010, 08:37 PM

I actually JUST did this. haha

Boost It Up - AP Boss Fuel Pump - Turbo Magazine

starting the car up tomorrow lol

*garagelu* · 10-18-2010, 08:44 PM

http://www.painlessperformance.com/Manuals/50102.pdf

Here's the kit I'm installing this week. I've been having fuel pressure drop after 6K rpm. I've narrowed it down to voltage drop so hopefully this fixes it.

Rabboni · 10-19-2010, 12:06 AM

I dont know... Im personally not a fan of running more wiring around my car that isnt absolutely necessary. Plus, if your having voltage drop problems with the factory wiring wouldnt it make sense to just fix the existing wiring, rather than to have bad wiring control a new relay?

nieko · 10-19-2010, 12:15 AM

Do you really want to go thru the whole car tracing the fuel pump power wire just to replace it?? when you could just run a new one and tuck it nicely or something?

And the old wiring still works, just doesnt hold the strong 12v at all times.

The old wiring is only clicking the relay on, should do the job just fine.

NiSilS14 · 10-19-2010, 12:16 AM

you could do this, but it requires a little more cash.
Kenne Bell Boost-A-Pump

jspaeth · 10-19-2010, 09:13 AM

Quote:

Originally Posted by Rabboni

I dont know... Im personally not a fan of running more wiring around my car that isnt absolutely necessary. Plus, if your having voltage drop problems with the factory wiring wouldnt it make sense to just fix the existing wiring, rather than to have bad wiring control a new relay?

Pretty much anyone who actually cares about their car and wants RELIABLE fuel delivery rewires the fuel pump directly to the battery.

IIRC, the factory setup has the fuel pump in a circuit with other things, and as the load on the car changes etc etc you can more easily get inconsistent voltage.

I measured the fuel pump voltage under my "OEM" wiring setup and I see about 12.5 volts.

However, the alternator puts out close to 14V when the car is running, so you should be able to utilize that advantage by wiring directly to the battery and getting 13.5-14.0 V to the pump.

Martino · 10-19-2010, 01:12 PM

Quote:

Originally Posted by jspaeth

Pretty much anyone who actually cares about their car and wants RELIABLE fuel delivery rewires the fuel pump directly to the battery.

IIRC, the factory setup has the fuel pump in a circuit with other things, and as the load on the car changes etc etc you can more easily get inconsistent voltage.

I measured the fuel pump voltage under my "OEM" wiring setup and I see about 12.5 volts.

However, the alternator puts out close to 14V when the car is running, so you should be able to utilize that advantage by wiring directly to the battery and getting 13.5-14.0 V to the pump.

Could you essentially just find the power wire off the sending unit, cut and splice into a power source on ignition?

Or does it need to go through the relay? Where's that specific relay?

jspaeth · 10-19-2010, 01:45 PM

Quote:

Originally Posted by Martino

Could you essentially just find the power wire off the sending unit, cut and splice into a power source on ignition?

Or does it need to go through the relay? Where's that specific relay?

The easiest way to do it is to use the OEM power wire running to the fuel pump as a TRIGGER on the coil side of a NEW, second relay.

Then, run the power to that relay DIRECTLY from the battery (if it's in the trunk that is cake).

This way you get the maximum voltage possible to the battery

Chrisq0904 · 10-19-2010, 03:56 PM

Im having issues with my fuel pump and I wanna directly wire it to the batt and after reading this I understand what I have to do. But I do not understand what wires go to where. If someone could post a write-up or pm me a step by step process on what wires go where that would be great. Thanks in advance, sorry if this is a "noob" post..

jeremy242 · 10-19-2010, 04:44 PM

Thanks for the input

Martino · 10-19-2010, 09:04 PM

Quote:

Originally Posted by jspaeth

The easiest way to do it is to use the OEM power wire running to the fuel pump as a TRIGGER on the coil side of a NEW, second relay.

Then, run the power to that relay DIRECTLY from the battery (if it's in the trunk that is cake).

This way you get the maximum voltage possible to the battery

I'm looking to do this exactly, especially because my battery is in the trunk.
My only issue is...I'm medicore at wiring and every diagram I've looked at confuses the fuck out of me LOL

Any godly chance you could ghetto rig me a diagram? haha.

<3 love you long time.

Chrisq0904 · 10-20-2010, 08:48 PM

Terminal 86 - Ground
Terminal 30 - Direct to battery with inline 30A fuse
Terminal 85 - B/Y wire from pump (trigger)
Terminal 87 - Other end of B/Y wire (trigger)

I think this is correct just unsure if i have the trigger wire correct.

240Zfunahollic · 10-20-2010, 08:57 PM

Deatschwerks sells everything you need for like $20.

jspaeth · 10-20-2010, 08:57 PM

Quote:

Originally Posted by Martino

I'm looking to do this exactly, especially because my battery is in the trunk.
My only issue is...I'm medicore at wiring and every diagram I've looked at confuses the fuck out of me LOL

Any godly chance you could ghetto rig me a diagram? haha.

<3 love you long time.

Okay get a NEW relay that can support the current (not sure how much).

You cut the power and ground wires going to the pump.

Run a new, thicker ground from the pump to chassis.

Take the OLD pump power wire, and run it to the + side of the coil on the relay. Run another wire from the ground side of the coil to the chassis.

Run a wire from the battery to the switched side of the relay, and then another wire from the other switched side of the relay to the + terminal of the pump.

IIRC, the current dircetion through the relay doesn't matter (wait for someone else to confirm this)

Rabboni · 10-20-2010, 09:57 PM

Quote:

Originally Posted by jspaeth

Pretty much anyone who actually cares about their car and wants RELIABLE fuel delivery rewires the fuel pump directly to the battery.

IIRC, the factory setup has the fuel pump in a circuit with other things, and as the load on the car changes etc etc you can more easily get inconsistent voltage.

I measured the fuel pump voltage under my "OEM" wiring setup and I see about 12.5 volts.

However, the alternator puts out close to 14V when the car is running, so you should be able to utilize that advantage by wiring directly to the battery and getting 13.5-14.0 V to the pump.

I still havnt done this, and i have never had any fuel delivery problems. Im probably not making nearly as much power as you though, so I see where you are coming from.

Continuing: http://4x4icon.com/offroad/headlight...ay_diagram.gif

85: this is where you would wire the power wire of your existing fuel pump wiring as the trigger.
86: this you would wire to a reliable chassis ground.
30: Wire your power wire from the battery here.
87: Run the power wire to your pump from here.

*slider2828* · 10-21-2010, 10:21 AM

Quote:

Originally Posted by 240Zfunahollic

Deatschwerks sells everything you need for like $20.

Thanks MAN!!! I just ordered this.... I didn't know a kit existed....

Plug and play is the best and it was $30 + 13 shipping....

Great thread, never checked for voltage drop, but since I do a lot of trackdayz I should have thought about this....

Great thread!

Martino · 10-21-2010, 12:53 PM

Quote:

Originally Posted by jspaeth

Okay get a NEW relay that can support the current (not sure how much).

You cut the power and ground wires going to the pump.

Run a new, thicker ground from the pump to chassis.

Take the OLD pump power wire, and run it to the + side of the coil on the relay. Run another wire from the ground side of the coil to the chassis.

Run a wire from the battery to the switched side of the relay, and then another wire from the other switched side of the relay to the + terminal of the pump.

IIRC, the current dircetion through the relay doesn't matter (wait for someone else to confirm this)

According to the Deatschwerks kit it includes a 30am relay so I'm assuming that would suffice?

And I just read that over again...
Still confused...I tried drawing a diagram of what you explained but I'm doing something wrong.

Ugh.

lok · 10-21-2010, 01:01 PM

this might help.

xiaphin · 10-21-2010, 01:04 PM

Deatschwerks Fuel Pump Hard Wire Kit - $29

*slider2828* · 10-21-2010, 01:17 PM

30AMP is more than enough....

jeremy242 · 10-21-2010, 02:35 PM

awesome diagram, it doesn't get any clearer then that.

Martino · 10-21-2010, 06:38 PM

So good.
I <3 you.

Bigsyke · 10-23-2010, 01:09 AM

Quote:

Originally Posted by jspaeth

Pretty much anyone who actually cares about their car and wants RELIABLE fuel delivery rewires the fuel pump directly to the battery.

by wiring directly to the battery and getting 13.5-14.0 V to the pump.

I sure hope not.

This mod has left me stranded before. Bosch 40amp relay crapped out on me pretty fast.

codyace · 10-23-2010, 11:39 AM

Quote:

Originally Posted by Bigsyke

I sure hope not.

This mod has left me stranded before. Bosch 40amp relay crapped out on me pretty fast.

That's a very rare occurance to be honest, only time I've ever had issues with relays failing (other than the random OE ones dying at the shop) are when I had some installed upside down (connector up) and rain water getting in them on a little off road buggy i had.

10-18-2010, 04:39 PM	#1
jeremy242 Leaky Injector Join Date: Aug 2007 Location: Oviedo, Fl Age: 39 Posts: 143 Trader Rating: (1) Feedback Score: 1 reviews	fuel pump direct battery power I have been advised that i should wire my fuel pump dirctly to the battery to reduce voltage drop. Can i just use the existing power source for the pump to trigger the relay and power the pump? Is it really that easy? Obviously i still have to wire up the rest of the relay but is that it? Thanks

10-18-2010, 05:21 PM	#3
Rabboni Zilvia Member Join Date: Aug 2009 Location: Fairfield, CA Posts: 230 Trader Rating: (0) Feedback Score: 0 reviews	If voltage drop through a relay was that much of a concern then they wouldnt be used at the factory. Dont wire it directly to battery power,just use the existing setup. __________________ Baling Wire-The Duct Tape Of Champions

10-18-2010, 05:37 PM	#6
roboticnissan Nissanaholic! Join Date: Mar 2007 Location: SOCAL/NORCAL Age: 32 Posts: 1,867 Trader Rating: (12) Feedback Score: 12 reviews	Use the existing relay. __________________

10-18-2010, 08:37 PM	#7
nieko Post Whore! Join Date: Sep 2007 Location: Westminster Age: 30 Posts: 2,694 Trader Rating: (14) Feedback Score: 14 reviews	I actually JUST did this. haha Boost It Up - AP Boss Fuel Pump - Turbo Magazine starting the car up tomorrow lol __________________

10-18-2010, 08:44 PM	#8
garagelu Premium Member Join Date: Aug 2005 Location: Atlanta, GA Age: 36 Posts: 1,856 Trader Rating: (60) Feedback Score: 60 reviews	http://www.painlessperformance.com/Manuals/50102.pdf Here's the kit I'm installing this week. I've been having fuel pressure drop after 6K rpm. I've narrowed it down to voltage drop so hopefully this fixes it. __________________ Instagram: @garagelu

10-18-2010, 05:15 PM	#2
R33E8 Zilvia Addict Join Date: Jul 2006 Location: NJ Age: 31 Posts: 797 Trader Rating: (14) Feedback Score: 14 reviews	Yes. it's really that easy..

10-18-2010, 05:24 PM	#4
jeremy242 Leaky Injector Join Date: Aug 2007 Location: Oviedo, Fl Age: 39 Posts: 143 Trader Rating: (1) Feedback Score: 1 reviews	I already have the battery in the back as it is, i would be using the factory fuel pump wiring as the trigger for the new relay to directly connect the pump to a good 12v source

10-18-2010, 05:29 PM	#5
jeremy242 Leaky Injector Join Date: Aug 2007 Location: Oviedo, Fl Age: 39 Posts: 143 Trader Rating: (1) Feedback Score: 1 reviews	i was more concerned with the 21 year old wiring that it was having to travel through rather than the factory set up

10-19-2010, 12:06 AM	#9
Rabboni Zilvia Member Join Date: Aug 2009 Location: Fairfield, CA Posts: 230 Trader Rating: (0) Feedback Score: 0 reviews	I dont know... Im personally not a fan of running more wiring around my car that isnt absolutely necessary. Plus, if your having voltage drop problems with the factory wiring wouldnt it make sense to just fix the existing wiring, rather than to have bad wiring control a new relay? __________________ Baling Wire-The Duct Tape Of Champions

10-19-2010, 12:15 AM	#10
nieko Post Whore! Join Date: Sep 2007 Location: Westminster Age: 30 Posts: 2,694 Trader Rating: (14) Feedback Score: 14 reviews	Do you really want to go thru the whole car tracing the fuel pump power wire just to replace it?? when you could just run a new one and tuck it nicely or something? And the old wiring still works, just doesnt hold the strong 12v at all times. The old wiring is only clicking the relay on, should do the job just fine. __________________

10-19-2010, 12:16 AM	#11
NiSilS14 Zilvia Junkie Join Date: Sep 2003 Location: Denver, CO Posts: 562 Trader Rating: (20) Feedback Score: 20 reviews	you could do this, but it requires a little more cash. Kenne Bell Boost-A-Pump

10-19-2010, 03:56 PM	#15
Chrisq0904 Zilvia Member Join Date: May 2009 Location: FL Age: 31 Posts: 152 Trader Rating: (4) Feedback Score: 4 reviews	Im having issues with my fuel pump and I wanna directly wire it to the batt and after reading this I understand what I have to do. But I do not understand what wires go to where. If someone could post a write-up or pm me a step by step process on what wires go where that would be great. Thanks in advance, sorry if this is a "noob" post..

10-19-2010, 04:44 PM	#16
jeremy242 Leaky Injector Join Date: Aug 2007 Location: Oviedo, Fl Age: 39 Posts: 143 Trader Rating: (1) Feedback Score: 1 reviews	Thanks for the input

10-20-2010, 08:48 PM	#18
Chrisq0904 Zilvia Member Join Date: May 2009 Location: FL Age: 31 Posts: 152 Trader Rating: (4) Feedback Score: 4 reviews	Terminal 86 - Ground Terminal 30 - Direct to battery with inline 30A fuse Terminal 85 - B/Y wire from pump (trigger) Terminal 87 - Other end of B/Y wire (trigger) I think this is correct just unsure if i have the trigger wire correct.

10-20-2010, 08:57 PM	#19
240Zfunahollic Zilvia Junkie Join Date: Aug 2003 Location: South Carolina Age: 35 Posts: 593 Trader Rating: (35) Feedback Score: 35 reviews	Deatschwerks sells everything you need for like $20. __________________ Visit My Trader rating page http://zilvia.net/f/traderratings.html?u=15347

10-21-2010, 01:01 PM	#24
lok Zilvia Addict Join Date: Jul 2003 Location: Oklahoma Posts: 790 Trader Rating: (10) Feedback Score: 10 reviews	this might help.

10-21-2010, 01:04 PM	#25
xiaphin Zilvia Junkie Join Date: Apr 2003 Location: Pleasanton Age: 37 Posts: 451 Trader Rating: (32) Feedback Score: 32 reviews	Deatschwerks Fuel Pump Hard Wire Kit - $29 __________________ 2018 Audi RS 3 \| Unitronic Stage 1 ECU and Stage 2 TCU tune Last edited by xiaphin; 10-21-2010 at 01:04 PM.. Reason: link edit

10-21-2010, 01:17 PM	#26
slider2828 Premium Member Join Date: Oct 2004 Location: San Francisco, CA Posts: 5,824 Trader Rating: (13) Feedback Score: 13 reviews	30AMP is more than enough.... __________________ Turn and Burn!

10-21-2010, 02:35 PM	#27
jeremy242 Leaky Injector Join Date: Aug 2007 Location: Oviedo, Fl Age: 39 Posts: 143 Trader Rating: (1) Feedback Score: 1 reviews	awesome diagram, it doesn't get any clearer then that.

10-21-2010, 06:38 PM	#28
Martino Zilvia FREAK! Join Date: Mar 2008 Location: Toronto, Canada Posts: 1,000 Trader Rating: (8) Feedback Score: 8 reviews	So good. I <3 you. __________________ IG: @vsMARTINO

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