No Power To Fuel Pump

[Crans]

Just tried hooking up a relay to my fuel pump to feed direct battery voltage to it and seams to be an epic failure

I was using a 12v 40amp normal open relay. It was wired up correctly

Blue trigger wire going into switch pin then battery to fuel pump on the switching side.

I measured voltage coming from the ecu and its nothing

Undid all changes and fuel pump still wont turn on.

Any one know what fuses i need to be checking?? I can find any blown ones.

[Hanaldo]

Seems unlikely, but you have got it earthed yeh?

When you say not turning on, does that mean it doesn't prime or do anything or you just can't start the car?

[Crans]

Dosn't even prime. I have now wired it back up like stock and it still won't even prime

[R.3.2.G.T.R]

did u disconnect battery when doing the changes, checked all the fuses under the drivers side panel?

[Crans]

Yeah battery was disconnected. No idea which fuse to check so i checked all the 20 and 15amp fuses any one got a diagram?

[Crans]

Stupid car fuel pump just started working, and now my F****n key just snaped. Can you get new keys cut from any key place??

[KiwiRS4T]

If you have the number Nissan can cut a new one from the code. Some locksmiths may be able to I don't know but the average key bar probably can't - they will need one to copy - should be possible if you can get the broken bit out.

[Crans]

Ive got the broken bit, broke off when i picked the keys up by the end of the key.

I'm about to park the damn car in the shed and forget about it, nothing seams to be going right on it

[Hanaldo]

Welcome to the modified car scene

[Torques]

The fuel pump fuse in in the back of the car (where the other fuses are)

It is labeled in English!

(I think 15A - blue)

Also, depending on how you hooked up your relay, you might have damaged your fuel pump controller.

(Just a thought)

Also I really don't know why people do this mod, since the fuel pump controller jumps to full voltage once

the car moves

There is no resistor which cripples the pump .. the FPC actually has logic and a number of components in it.

Hope this helps ..

Edited August 28, 2011 by Torques

[Hanaldo]

Also I really don't know why people do this mod, since the fuel pump controller jumps to full voltage once

the car moves

There is no resistor which cripples the pump .. the FPC actually has logic and a number of components in it.

Well voltage is only one part of it, you need the wiring to be able to handle a higher amperage as well. Secondly, lots of people have problems with surging at idle and low rpm because aftermarket fuel pumps are designed to be run at alternator current.

[Torques]

Hello ..

I recently installed a Tomei, and it hums along just fine.

But higher load as in 'wattage' could be an issue if your overstress the pump controller.

Still there are people out there who do the 'fuel-pump-mod' with the standard pump installed.

I find this useless ..

Well voltage is only one part of it, you need the wiring to be able to handle a higher amperage as well. Secondly, lots of people have problems with surging at idle and low rpm because aftermarket fuel pumps are designed to be run at alternator current.

[Hanaldo]

Still there are people out there who do the 'fuel-pump-mod' with the standard pump installed.

I find this useless ..

Oh right. Yeh I see so little reason for this that I didn't even consider that there were people doing it... lol.

[MrStabby]

Also I really don't know why people do this mod, since the fuel pump controller jumps to full voltage once

the car moves

Once that box fails, the direct wire is a good option I've had two die.... but agree that for many people its pointless. They just get scared when they see the lower voltage across the pump when the soft earth is switched in because they measure at idle or ign.

OP - the earth is switched - not power, so depending on how you're looking at it you will just see an earth from the ECU, or more accurately, from the fuel pump control module. Can remember if power is switched as well.

[Crans]

So the earth and the power wire from the ecu both need to be connected to the switch side of the relay?? Pretty sure that exactly how I had it connected.

I'm running a deatschwerks 300L{H fuel pump and it needs as much voltage as you can give it. Im also running Deatschwerks 740cc njectors so im wanted to make sure fuel pressure is spot on.

Got 2 keys cut and 1 works so im mobile again. I will try and do the rewire again this weekend.

[Torques]

Yep,

The fuel pump gets + (12V) via the relay which is triggered directly by the ECU.

The ground side of the pump is connected to the FPCM (which in turn is some kind of floating ground if you will).

If I were to do this mod, I'd unplug the FPCM and bridge connectors 3 + 1.

No relay or anything needed.

I'm running the Z32 ECU, and this one does 3 voltage steps ..

Once that box fails, the direct wire is a good option I've had two die.... but agree that for many people its pointless. They just get scared when they see the lower voltage across the pump when the soft earth is switched in because they measure at idle or ign.

OP - the earth is switched - not power, so depending on how you're looking at it you will just see an earth from the ECU, or more accurately, from the fuel pump control module. Can remember if power is switched as well.

Edited August 29, 2011 by Torques

[Torques]

The pump is only reduced in voltage when the car is at idle, once things get in motion the FPCM switches over to full voltage.

I doubt you will need 300L/H at idle, so why bother?

The whole concept is that Nissan wanted to reduce noise from the pump when the car is stopped.

Personally I hate that whining sound and it bothers me.

(my car is also my daily drive and I also like my car to be 'neat' and fast)

So the earth and the power wire from the ecu both need to be connected to the switch side of the relay?? Pretty sure that exactly how I had it connected.

I'm running a deatschwerks 300L{H fuel pump and it needs as much voltage as you can give it. Im also running Deatschwerks 740cc njectors so im wanted to make sure fuel pressure is spot on.

Got 2 keys cut and 1 works so im mobile again. I will try and do the rewire again this weekend.

Edited August 29, 2011 by Torques

[Brezza]

i'd be checking the earth, and making sure it is fine all the way to the pump.

i had a dodgy earth connection on my fuel pump through the tank lid and it wouldn't supply enough power to the twin in tank pumps i've got.

[miga24]

first check the blue 15a fuse in the boot, than go to the fuse box below the steering wheel, its the A/T fuse, third one down on the right hand side 10A after that check the relay by taking off one from the Air con, than u shuld take the fuel pump and directly link the wires to the battery to check if its working if the above fail.

[Crans]

Auto electrician looked over my car today and re wired my fuel pump for me. Checked out there job and turns out i did mine exactly the same as they have done it.

Must have been a faulty relay