Anyone know where the Fuel Pump relay is located on an 01 X w/ 3.3 V6?
I'm looking at the ESM and it's pretty vaigue. Pretty much points to the center of the dashboard. LOL
Can you be a little more specific?

Maybe someone else has a better idea of its location.

I'm starting simple with trying to figure out why my truck likes to eat Fuel Sending units on a monthly basis.

I have a replacement fuel pump standing by.
Just figured I'd start easy before dealing with the pump.

Anyone have other ideas?

The truck has been sitting since November unstarted because of the fuel pump issue.
Now I'm finally getting around to dealing with it.

Thanks!!

Unfortunately, there are like 10 randomely placed relays throughout the dash. I do not know if I can point you do the exact one.

I'm going to throw a fully charge on the battery then hit the fuel sending unit harness with a multi-meter to test for voltage.
I assume it should be at very least 12 volts when you kick the key forward.

I'm not hearing the pump kick on when I put the key forward.
When I replace the FSU it runs fine, but it burns out in a month or less.

Anyone ever have problems with the wiring to the fuel pump inside the tank?
Maybe that's the problem..

Some more info...

Alrighty..
I threw a charge on the battery (well, still charging only at 10.8 volts right now) and I was playing with the multimeter in the fuel pump wiring harness.
When I kick the key forward I definitely hear a click from the center of the dashboard.
That would mean that the fuel pump relay is working properly. :mrgreen: :banana:

There are two wiring harnesses attached to the Fuel Sending Unit.
One has Two wires going to it. (white w/ blue stripe and black)
The other has three wires going to it. (yellow w/ black stripe, black and orange w/ black stripe)
I hooked the multimeter to the white and black wires and no current at all.
I got 4.8 volts plus or minus (battery isn't fully charged yet) from the Orange w/ black stripe wire.
I got about 9.8 volts or so from the Yellow w/ black stripe wire.

Obviously black is ground.

Any ideas if I should be getting any voltage at the two wire harness?

Maybe the ESM will be good for that at least?

I know this isn't much help Ken but here is a pic of somewhat the relative location under the dash of the relay.

http://i8.photobucket.com/albums/a50/dezurtrat/Xterra/X_00/fuel_pmp_Rly_loc.jpg

That's pretty funny actually.
After I removed the cover under the steering wheel and the cover under the radio/heater controls, that relay flopped down on it's own. LOL

What are the odds that Nissan actually put the fuel pump relay in an accessible location and made it obvious.

I'll check if that relay is clicking. I believe it is.

I'm getting decent volt readings at the harness by the fuel sending unit.
So looks like I'll be smelling like old 87 octane for the next few days.
Gotta pull the pump and wiring.

After pulling some stuff apart I figured out the problem (well, kinda)
The two wire harness is actually what powers the fuel pump not the three wire harness.

I have a bad feeling that I've been replacing FSU's for NO REASON. :shock:

I have ZERO voltage at the harness for the fuel pump.
I hear a click from the dash board but I don't think it's from the fuel pump relay.
Held the FP relay while kicking the key forward and it doesn't do anything.

I have to figure out how to remove that relay and replace it.
Kinda makes sense that it is causing the lack of fuel and has been tempermental.

I highly doubt there is anything wrong with my fuel pump. :roll:
So I'm off to try to pull the relay and swap something else in it's place temporarily.

Thanks for the diagram Mike. It definitely helps.

the relay shouldn't be to much unless it is different from all the other relays in the x.... pop the hood and take out the fog light relay and see if it work for the relay under the dash... if it dose then just go to a auto parts store and get a new relay and put it in the fog light spot or switch them around so the new relay is under the dash... like i said they should be the same since Nissan used the same relay for everything in the relay box under the hood... let us know if it works for you...

I popped out the relay and ordered a replacement from my local parts stock.
$20 and it'll be here tomorrow morning.

I'll plug the new relay in and test the voltage at the fuel pump harness again.
Hopefully I'll have 12 volts when the key is turned.

If that's the case, then I'm set.

Hopefully that solves it for you!

good luck and let us know if it worked...

Not good..
I swapped in the new relay and still no power to the FSU harness (to the pump).
I took my FSU and spare pump and hooked it directly up to the battery and it turns on with no issues.
Looks like all of my FSU's that have been replaced were actually fine.

The quick fix for this is to run a ground and a hot lead from a switch to the fuel pump harness to power it before the fuel sending unit connection.
That should turn on the fuel pump with no problems.

I'm trying to avoid installing a fuel pump switch in my truck since obviously there is a bigger problem I'm just putting a band-aid over.


I guess I'll just trace the harness back to where it splits and see if the wires are screwed up or not.
On a side note, the fuel gauge works fine, and that harness gets power no problem.
That harness and the fuel pump harness connect together.
Don't understand why one would work and not the other.

I checked ALL fuses, and ALL related relays.
I'm definitely hearing a click when I kick the key forward from the dash. Can't tell if it's coming from the relay I just replaced or not.

Pretty f-ing annoying.

Well, back to more troubleshooting.

Ken, the ECU controls the switching to ground of the fuel pump. Any chance you have an issue with the ECU???

EDIT: Actually, let me restate that. It controls the switching to ground of the fuel pump relay. So, if the ECU isn't switching it to ground. No 12V to the fuel pump. Just and idea though not a pleasant one as I'm sure the ECU is costly.

ugh...
Thanks Mike.
I responded on LINXC.

Long and short of it...
Fuel pump and FSU only kicks on if I run power directly to it.
So if I wire up a Fuel Pump switch it'll work fine...BUT..
I'm kinda avoiding the main issue.

Any more ideas?
I'm not liking that ECU replacement idea.

the simple check is to make a jumper wire and jump the relay socket to do the job of the relay. This confirms operation which youve done I believe although in a real round about way. You need to use a multimeter and check for signal from the ecu to the relay socket. Without looking at a wiring diagram I cant tell you which one but the trigger from ecu are normally ground triggers on todays cars and a small wire. minimun is a large power wire with 12v, and same size wire to pump. then a always 12v with key on, then youre trigger wire from ecu. you really need a wiring diag to proplerly diag and is way cheaper than throwing parts at it.

Ahhh, he fixed it but I'll let him post up!!! Simple fix which I think he's beating himself for right now! :)

Yeah, as Mike said.. It's fixed..

Where the fuse goes in was widened up too much, so one side wasn't making contact with the fuse.
I took a small precision screwdriver and bent the prongs back down and the fuse completes the circuit and I have power to the relay.

Put the key forward and I hear the fuel pump kicking on once again.

I threw a charge on the battery and it started right up.

After sitting for 6 months and this was all it was?! ugh..

Thanks again guys!

glad you go it fixed...

Yeah, as Mike said.. It's fixed..

Where the fuse goes in was widened up too much, so one side wasn't making contact with the fuse.
I took a small precision screwdriver and bent the prongs back down and the fuse completes the circuit and I have power to the relay.

Put the key forward and I hear the fuel pump kicking on once again.

I threw a charge on the battery and it started right up.

After sitting for 6 months and this was all it was?! ugh..

Thanks again guys!
sounds like someone used a fuse tap to provide for ignition feed itstead of doing it the correct way....never fails to screw stuff up